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					OPTIMIZATION

BASICS

CHANNELS

Downlink

Uplink

Physical channel - Each timeslot on a carrier is referred to as a physical channel. Per carrier there are 8 physical channels. Logical channel - Variety of information is transmitted between the MS and BTS. There are different logical channels depending on the information sent. The logical channels are of two types • Traffic channel • Control channel

GSM Traffic Channels

Traffic Channels

TCH/F Full rate 22.8kbits/s

TCH/H Half rate 11.4 kbits/s

GSM Control Channels
Control Channels

BCH ( Broadcast channels ) Downlink only

CCCH(Common Control Chan) Downlink & Uplink

DCCH(Dedicated Channels) Downlink & Uplink

BCCH
Broadcast control channel

Synch. Channels

Random Access Channel

RACH

Cell Broadcast Channel

CBCH

SDCCH
Standalone dedicated control channel

Associated Control Channels

ACCH

SCH
Synchronisation channel

Frequency Correction channel

FCCH

Paging/Access grant

PCH/ AGCH

Fast Associated Control Channel

FACCH

Slow associated Control Channel

SACCH

BCH Channels BCCH( Broadcast Control Channel ) • Downlink only • Broadcasts general information of the serving cell called System Information • BCCH is transmitted on timeslot zero of BCCH carrier • Read only by idle mobile at least once every 30 secs. SCH( Synchronisation Channel ) • Downlink only • Carries information for frame synchronisation. Contains TDMA frame number and BSIC. FCCH( Frequency Correction Channel ) • Downlink only. • Enables MS to synchronise to the frequency. • Also helps mobiles of the ncells to locate TS 0 of BCCH carrier.

CCCH Channels RACH( Random Access Channel ) • Uplink only • Used by the MS to access the Network.

AGCH( Access Grant Channel ) • Downlink only • Used by the network to assign a signaling channel upon successful decoding of access bursts.

PCH( Paging Channel ) • Downlink only. • Used by the Network to contact the MS.

DCCH Channels SDCCH( Standalone Dedicated Control Channel ) • Uplink and Downlink • Used for call setup, location update and SMS. SACCH( Slow Associated Control Channel ) • Used on Uplink and Downlink only in dedicated mode. • Uplink SACCH messages - Measurement reports. • Downlink SACCH messages - control info. FACCH( Fast Associated Control Channel ) • Uplink and Downlink. • Associated with TCH only. • Is used to send fast messages like handover messages. • Works by stealing traffic bursts.

26 FRAME MULTIFRAME STRUCTURE
4.615 msec 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7

T T T T T T T T T T T T S T T T T T T T T T T T T I 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 120 msec

• • • •

MS on dedicated mode on a TCH uses a 26-frame multiframe structure. Frame 0-11 and 13-24 used to carry traffic. Frame 12 used as SACCH to carry control information from and to MS to BTS. Frame 25 is idle and is used by mobile to decode the BSIC of neighbor cells.

BCCH/CCCH NON-COMBINED MULTIFRAME
Downlink
50
CCCH CCCH BCCH

Uplink
IDLE CCCH BLOCK BCCH BLOCK SCH BLOCK FCCH BLOCK RACH BLOCK

50

40
CCCH CCCH BCCH

40

30
CCCH CCCH BCCH

30

20
CCCH CCCH

20

10
CCCH BCCH

10

0

0

BCCH/CCCH COMBINED MULTIFRAME
Downlink
50
SACCH CCCH SACCH BCCH

Uplink
101
SACCH CCCH SACCH BCCH

40
SDCCH CCCH SDCCH CCCH SDCCH SDCCH

IDLE CCCH BLOCK BCCH BLOCK SCH BLOCK FCCH BLOCK RACH BLOCK SDCCH/4 SACCH/4

50

SDCCH CCCH

101

SDCCH CCCH

SDCCH CCCH

SDCCH CCCH

40

SDCCH CCCH

SDCCH CCCH

30
SDCCH CCCH SDCCH CCCH SDCCH CCCH BCCH SDCCH CCCH BCCH

30

20
CCCH CCCH CCCH CCCH

20

SACCH CCCH

SACCH CCCH

10
CCCH CCCH BCCH BCCH

10
SACCH CCCH SACCH CCCH

SDCCH CCCH BCCH

SDCCH CCCH BCCH

0

51

0

51

DCCH/8 MULTIFRAME
Downlink
50
CCCH A3

Uplink
101
CCCH A7

IDLE SDCCH/8 SACCH/C8

50

BCCH A0

101

BCCH A4

CCCH D7

CCCH D7

BCCH A2

BCCH A6

40
CCCH A1 CCCH A5 BCCH A0 BCCH A4

40

CCCH D6

CCCH D6

CCCH D5

CCCH D5

CCCH D4

CCCH D4

30

CCCH D7

CCCH D7

30

CCCH D3

CCCH D3

CCCH D6

CCCH D6

CCCH D2

CCCH D2

CCCH D5

CCCH D5

20
CCCH D4 CCCH D4 CCCH D3 CCCH D3

20

CCCH D1

CCCH D1

CCCH D0

CCCH D0

10

CCCH D2

CCCH D2

10

CCCH A7

CCCH A3

CCCH D1

CCCH D1

BCCH A6

BCCH A2

CCCH D0

CCCH D0

CCCH A5

CCCH A1

0

51

0

51

HYPERFRAME AND SUPERFRAME STRUCTURE
3h 28min 53s 760ms 0 6.12s 0 1 2 1 2 1 Hyperframe = 2048 superframes = 2,715,648 TDMA frames 2045 2046 2047

1 Superframe = 1326 TDMAframes = 51(26 fr) 0r 26(51 fr) multiframes 3 47 48 49 50

0

1

24

25

120ms 0 1 2 23 24 25 0 1 2

235.38ms 48 49 50

Traffic 26 - Frame Multiframe
4.615ms 0 1 2 3 4 5 6 7

Control 51 - Frame Multiframe

TDMA Frame

CALL FLOW

Mobile originated call
MS
Channel Request (RACH) Immediate Assignment [ Reject ] (AGCH)

BSS

MSC

SDCCH Seizure
CM Service Request + Connection Request < CMSREQ > Connection [ Confirmed / Refused ]

Link Establishment
Authentication Request Authentication Response DT1 <CICMD> DT1 <CICMP>

S D C C H

Ciphering Mode Command Ciphering Mode Complete

Identity Request Identity Response Setup Call Proceeding

Connection Management
Assignment Request Assignment Request [ Failed ] Assignment Command Assignment [ Complete / Failure ] Assignment [ Complete / Failure ]

T C H

TCH Seizure

Mobile terminated call
MS
Paging Request (PCH)

BSS
UDT < PAGIN >

MSC

Paging
Channel Request (RACH) Immediate Assignment [ Reject ] (AGCH)

SDCCH Seizure
Paging Response + Connection Request < PAGRES > Connection [ Confirmed / Refused ]

Link Establishment
Authentication Request Authentication Response DT1 <CICMD> DT1 <CICMP>

Ciphering Mode Command

S D C C H

Ciphering Mode Complete

Identity Request Identity Response Setup Call Confirmed

Connection Management
Assignment Request Assignment Request [ Failed ] Assignment Command Assignment [ Complete / Failure ]

T C H

Assignment [ Complete / Failure ]

TCH Seizure

PROPAGATION MECHANISMS Reflection • Occurs when a wave impinges upon a smooth surface. • Dimensions of the surface are large relative to . • Reflections occur from the surface of the earth & from buildings & walls. Diffraction (Shadowing) • Occurs when the path is blocked by an object with large dimensions relative to  and sharp irregularities (edges). • Secondary “wavelets” propagate into the shadowed region. • Diffraction gives rise to bending of waves around the obstacle.

Scattering • Occurs when a wave impinges upon an object with dimensions on the order of  or less, causing the reflected energy to spread out or“scatter” in many directions. • Small objects such as street lights, signs, & leaves cause scattering

Multipath • Multiple Waves Create “Multipath” • Due to propagation mechanisms, multiple waves arrive at the receiver • Sometimes this includes a direct Line-of-Sight (LOS) signal

Multipath Propagation • Multipath propagation causes large and rapid fluctuations in a signal • These fluctuations are not the same as the propagation path loss. Multipath causes three major things • Rapid changes in signal strength over a short distance or time. • Random frequency modulation due to Doppler Shifts on different multipath signals. • Time dispersion caused by multipath delays • These are called “fading effects • Multipath propagation results in small-scale fading.

Fading • • • The communication between the base station and mobile station in mobile systems is mostly non-LOS. The LOS path between the transmitter and the receiver is affected by terrain and obstructed by buildings and other objects. The mobile station is also moving in different directions at different speeds.

•
•

The RF signal from the transmitter is scattered by reflection and diffraction and reaches the receiver through many non-LOS paths.
This non-LOS path causes long-term and short term fluctuations in the form of log-normal fading and rayleigh and rician fading, which degrades the performance of the RF channel.

FADING

Signal Power (dBm)

Large scale fading component

Small scale fading component

Long Term Fading • • Terrain configuration & man made environment causes long-term fading. Due to various shadowing and terrain effects the signal level measured on a circle around base station shows some random fluctuations around the mean value of received signal strength. The long-term fades in signal strength, r, caused by configuration and man made environments form a distribution, i.e the mean received signal strength, r, normally in dB if the signal strength is measured over a at least 40. the terrain log-normal varies logdistance of

•

•

Experimentally it has been determined that the standard deviation, , of the mean received signal strength, r, lies between 8 to 12 dB with the higher  generally found in large urban areas.

Rayleigh Fading • This phenomenon is due to multipath propagation of the signal. • The Rayleigh fading is applicable to obstructed propagation paths.

• All the signals are NLOS signals and there is no dominant direct path.
• Signals from all paths have comparable signal strengths. • The instantaneous received power seen by a moving antenna becomes a random variable depending on the location of the antenna.

Ricean Fading • This phenomenon is due to multipath propagation of the signal. • In this case there is a partially scattered field. • One dominant signal. • Others are weaker.

ANTENNAS

Antennas • • • • Antennas form a essential part of any radio communication system. Antenna is that part of a transmitting or receiving system which is designed to radiate or to receive electromagnetic waves. An antenna can also be viewed as a transitional structure between free-space and a transmission line (such as a coaxial line). An important property of an antenna is the ability to focus and shape the radiated power in space e.g.: it enhances the power in some wanted directions and suppresses the power in other directions. Many different types and mechanical forms of antennas exist. Each type is specifically designed for special purposes.

• •

Antenna Types • In mobile communications two main categories of antennas used are – Omni directional antenna • • • These antennas are mostly used in rural areas. In all horizontal direction these antennas radiate with equal power. In the vertical plane these antennas radiate uniformly across all azimuth angles and have a main beam with upper and lower side lobes.

– Directional antenna • These antennas are mostly used in mobile cellular systems to get higher gain compared to omni directional antenna and to minimise interference effects in the network. • In the vertical plane these antennas radiate uniformly across all azimuth angles and have a main beam with upper and lower side lobes. • In these type of antennas, the radiation is directed at a specific angle instead of uniformly across all azimuth angles in case of omni antennas.

Radiation Pattern • The main characteristics of antenna is the radiation pattern. • The antenna pattern is a graphical representation in three dimensions of the radiation of the antenna as a function of angular direction. • Antenna radiation performance is usually measured and recorded in two orthogonal principal planes (E-Plane and H-plane or vertical and horizontal planes).

• The pattern of most base station antennas contains a main lobe and several minor lobes, termed side lobes.
• A side lobe occurring in space in the direction opposite to the main lobe is called back lobe.

Radiation Pattern

Antenna Gain • Antenna gain is a measure for antennas efficiency. • Gain is the ratio of the maximum radiation in a given direction to that of a reference antenna for equal input power. • Generally the reference antenna is a isotropic antenna. • Gain is measured generally in “decibels above isotropic(dBi)” or “decibels above a dipole(dBd). • An isotropic radiator is an ideal antenna which radiates power with unit gain uniformly in all directions. dBi = dBd + 2.15 • Antenna gain depends on the mechanical size, the effective aperature area, the frequency band and the antenna configuration. • Antennas for GSM1800 can achieve some 5 to 6 dB more gain than antennas for GSM900 while maintaining the same mechanical size.

Main Lobe Axis ½ Power Beamwidth

First Null

Side Lobe

Back Lobe

Front-to-back ratio • It is the ratio of the maximum directivity of an antenna to its directivity in a specified rearward direction.

• Generally antenna with a high front-to-back ratio should be used.

First Null Beamwidth • The first null beamwidth (FNBW) is the angular span between the first pattern nulls adjacent to the main lobe. • This term describes the angular coverage of the downtilted cells.

Antenna Lobes • Main lobe is the radiation lobe containing the direction of maximum radiation.

• Side lobes
Half-power beamwidth • The half power beamwidth (HPBW) is the angle between the points on the main lobe that are 3dB lower in gain compared to the maximum. • Narrow angles mean good focusing of radiated power. Polarisation • Polarisation is the propagation of the electric field vector .

• Antennas used in cellular communications are usually vertically polarised or cross polarised.

Frequency bandwidth • It is the range of frequencies within which the performance of the antenna, with respect to some characteristics, conforms to a specified standard. • VSWR of an antenna is the main bandwidth limiting factor. Antenna impedance • Maximum power coupling into the antennas can be achieved when the antenna impedance matches the cables impedance. • Typical value is 50 ohms. Mechanical size • Mechanical size is related to achievable antenna gain. • Large antennas provide higher gains but also need care in deployment and apply high torque to the antenna mast.

• Antenna radiation pattern will become superimposed when the distance between the antennas becomes too small.

• This means the other antenna will mutually influence the individual antenna patterns.
• Generally 5 to 10 horizontal separation provides sufficient decoupling of antenna patterns.

• The vertical distance needed for decoupling is usually much smaller as the vertical beamwidth is generally less.
• A 1 separation in the vertical direction is sufficient in most cases.

• Antenna installation configurations depend on the operators preferences. • It is important to keep sufficient decoupling distances between antennas.

• If TX and RX direction use separated antennas, it is advisable to keep a horizontal separation between the antennas in order to reduce the TX signal power at the RX input stages.

Antenna downtilt introduction • Network planners often have the problem that the base station antenna provides an overcoverage. • If the overlapping area between two cells is too large, increased switching between the base station (handover) occurs. • There may even be interference of a neighbouring cell with the same frequency. • If hopping is used in the network, then limiting the overlap is required to reduce the overall hit rate. • In general, the vertical pattern of an antenna radiates the main energy towards the horizon. • Only that part of the energy which is radiated below the horizon can be used for the coverage of the sector. • Downtilting the antenna limits the range by reducing the field strength in the horizon.

Antenna downtilting • Antenna downtilting is the downward tilt of the vertical pattern towards the ground by a fixed angle measured w.r.t the horizon.

• Downtilting of the antenna changes the position of the half-power beamwidth and the first null relative to the horizon.
• Normally the maximum gain is at 0• (parallel to the horizon) and never intersects the horizon. • A small downtilt places the beams maximum at the cell edge • With appropriate downtilt, the received signal strength within the cell improves due to the placement of the main lobe within the cell radius and falls off in regions approaching the cell boundary and towards the reuse cell. • There are two methods of downtilting – Mechanical downtilting – Electrical downtilting.

Mechanical Downtilt • Mechanical downtilting consists of physically rotating an antenna downward about an axis from its vertical position. • In a mechanical downtilt as the front lobe moves downward the back lobe moves upwards. • This is one of the potential drawback as compared to the electrical downtilt because coverage behind the antenna can be negatively affected as the back lobe rises above the horizon. • Additionally , mechanical downtilt does not change the gain of the antenna at +/- 90deg from antenna horizon. • As the antenna is given downtilt, the footprint starts changing with a notch being formed in the fron‟t while it spreads on the sides. • After 10 degrees downtilt the notch effect is quiet visible and the spread on the sides are high. This may lead to inteference on the sides.

Mechanical Downtilt

Mechanical Downtilt

Mechanical Downtilt

Vertical antenna pattern at 0

Vertical antenna pattern at 15 downtilt Backlobe shoots over the horizon

Electrical downtilt • Electrical downtilt uses a phase taper in the antenna array to angle the pattern downwards.

•
• • • •

This allows the the antenna to be mounted vertically.
Electrical downtilt is the only practical way to achieve pattern downtilting with omnidirectional antennas. Electrical downtilt affects both front and back lobes. If the front lobe is downtilted the back lobe is also downtilted by equal amount. Electrical downtilting also reduces the gain equally at all angles on the horizon. The that adjusted downtilt angle is constant over the whole azimuth range. Variable electrical downtilt antennas are very costly.

•

Electrical downtilt

Electrical downtilt

Obstacle requirement • • Nearby obstacles are those reflecting or shadowing materials that can obstruct the radio beam both in horizontal and vertical planes. When mounting the antenna on a roof top, the dominating obstacle in the vertical plane is the roof edge itself and in the horizontal plane, obstacles further away like surrounding buildings, can act as reflecting or shadowing material. The antenna beam will be distorted if the antenna is too close to the roof. Hence the antenna must be mounted at a minimum height above the rooftop or other obstacles. If antennas are wall mounted, a safety margin of 15 degrees between the reflecting surface and the 3-dB lobe should be kept.

•

•

Obstacle requirement

Safety Margin 15 Degrees

Building

Main Radiation Direction

Half Power Beamwidth

Optimal Downtilt • Although the use of downtilt can be a effective tool for controlling interference, there is a optimum amount by which the antenna can be downtilted whereby both the coverage losses and the interference at the reuse cell can be kept at a minimum.
 downtilt angle (D)

Height (H)

3 dB Beamwidth Main lobe

 Cellmax

Optimal Downtilt • The figure shows a cells coverage area. • The primary illumination area is the area on the ground that receives the signal contained within the 3dB vertical beam width of the antenna. • The distance from the base station to the outer limit of the illumination area is denoted by Cellmax. • It should be noted that the cellmax can be different from the cell boundary area which is customer defined. • Ideally in a well planned network Cellmax should always be less than the co-channel reuse distance to minimise interference. • We now derive the relation between height (H), downtilt angle (D), 3dB vertical beamwidth and Cellmax. • As shown in the schematic  is the angle between the upper limit of the 3dB beamwidth and the horizon.

Optimal Downtilt • tan ( ) = Cellmax / H  = D - 0.5 * 3dB vertical beamwidth Cellmax = H * tan (D - 0.5 * 3dB vertical beamwidth) • For the Cellmax to be a positive quantity , downtilt angle must be more than half of the 3dB vertical beamwidth. • When the downtilt angle is less than half of the 3dB beamwidth, part of the signal from the main beam shoots over the horizon . • The signal directed towards or above the horizon can potentially cause interference at the reuse sites.

INTERFERENCE

WHAT IS INTERFERNCE ?

•

Interference is the sum of all signal contributions that are neither noise not the wanted signal.

EFFECTS OF INTERFERNCE • • • • • • Interference is a major limiting factor in the performance of cellular systems. It causes degradation of signal quality. It introduces bit errors in the received signal. Bit errors are partly recoverable by means of channel coding and error correction mechanisms. The interference situation is not reciprocal in the uplink and downlink direction. Mobile stations and base stations are exposed to different interference situation.

SOURCES OF INTERFERNCE • • • • Another mobile in the same cell. A call in progress in the neighboring cell. Other base stations operating on the same frequency. Any non-cellular system which leaks energy into the cellular frequency band.

TYPES OF INTERFERNCE • There are two types of system generated interference – Co-channel interference – Adjacent channel interference Co-Channel Interference • • • This type of interference is the due to frequency reuse , i.e. several cells use the same set of frequency. These cells are called co-channel cells. Co-channel interference cannot be combated by increasing the power of the transmitter. This is because an increase in carrier transmit power increases the interference to neighboring co-channel cells. To reduce co-channel interference, co-channel cells must be physically separated by a minimum distance to provide sufficient isolation due to propagation or reduce the footprint of the cell.

•

Co-Channel Interference • • Some factors other then reuse distance that influence co-channel interference are antenna type, directionality, height, site position etc, GSM specifies C/I > 9dB.

Carrier f1 dB

Interferer f1

C

I
Distance

Co-Channel Interference

D
C1 C1

C3

C2

C3

C2

•

In a cellular system, when the size of each cell is approximately the same, co-channel interference is independent of the transmitted power and becomes a function of cell radius(R) and the distance to the centre of the nearest co-channel cell (D).

Co-Channel Interference • • Q = D / R = 3N By increasing the ratio of D/R, the spatial seperation between the cochannel cells relative to the coverage distance of a cell is increased. In this way interference is reduced from improved isolation of RF energy from the co-channel cell. The parameter Q , called the co-channel reuse ratio, is related to the cluster size. A small value of Q provides larger capacity since the cluster size N is small whereas a large value of Q improves the transmission quality.

• •

Adjacent-Channel Interference • Interference resulting from signals which are adjacent in frequency to the desired signal is called adjacent channel interference.

•
•

Adjacent channel interference results from imperfect receiver filters which allow nearby frequencies to leak into the passband.
Adjacent channel interference can be minimized through careful filtering and channel assignments.

•

By keeping the frequency separation between each channel in a given cell as large as possible , the adjacent interference may be reduced considerably.

Adjacent-Channel Interference

Carrier f1 dB

Interferer f2

A C Distance

POWER CONTROL • RF power control is employed to minimize the transmit power required by MS or BS while maintaining the quality of the radio links. By minimizing the transmit power levels, interference to co-channel users is reduced. Power control is implemented in the MS as well as the BSS. Power control on the Uplink also helps to increase the battery life. Power received by the MS is continuously sent in the measurement report. Similarly uplink power received from the MS by the BTS is measured by the BTS. Complex algorithm evaluate this measurements and take a decision subsequently reducing or increasing the power in the Uplink or the downlink.

•
• • • • •

SECTORIZATION • For 120 degrees sectored site as compared to an omni site almost 1/3rd interference is received in the uplink.

•
•

The more selective and directional is the antenna, the smaller is the interference. Reduction in interference results in higher capacity in both links.

DIVERSITY ANTENNA SYSTEMS

NEED OF DIVERSITY

Building

Building Building

NEED OF DIVERSITY • In a typical cellular radio environment, the communication between the cell site and mobile is not by a direct radio path but via many paths. • The direct path between the transmitter and the receiver is obstructed by buildings and other objects. • Hence the signal that arrives at the receiver is either by reflection from the flat sides of buildings or by diffraction around man made or natural obstructions. • When various incoming radiowaves arrive at the receiver antenna, they combine constructively or destructively, which leads to a rapid variation in signal strength. • The signal fluctuations are known as „multipath fading‟.

Multipath Propagation • Multipath propagation causes large and rapid fluctuations in a signal • These fluctuations are not the same as the propagation path loss. Multipath causes three major things • Rapid changes in signal strength over a short distance or time. • Random frequency modulation due to Doppler Shifts on different multipath signals. • Time dispersion caused by multipath delays • These are called “fading effects • Multipath propagation results in small-scale fading.

DIVERSITY TECHNIQUE • Diversity techniques have been recognised as an effective means which enhances the immunity of the communication system to the multipath fading. GSM therefore extensively adopts diversity techniques that include
Diversity techniques Interleaving In time domain Frequency Hopping In Frequency domain Spatial diversity In spatial domain Polarisation diversity In polarisation domain

CONCEPT OF DIVERSITY ANTENNA SYSTEMS • Spatial and polarisation diversity techniques are realised through antenna systems. • A diversity antenna system provides a number of receiving branches or ports from which the diversified signals are derived and fed to a receiver. The receiver then combines the incoming signals from the branches to produce a combined signal with improved quality in terms of signal strength or signal-to-noise ratio (S/N). • The performance of a diversity antenna system primarily relies on the branch correlation and signal level difference between branches.

CONCEPT OF DIVERSITY ANTENNA SYSTEMS

Fade

Transmission media 1

Information

Transmission Tmedia 2
Peak

Receiver

SPATIAL DIVERSITY ANTENNA SYSTEMS • The spatial diversity antenna system is constructed by physically separating two receiving base station antennas. • Once they are separated far enough, both antennas receive independent fading signals. As a result, the signals captured by the antennas are most likely uncorrelated. • The further apart are the antennas, the more likely that the signals are uncorrelated. • The types of the configuration used in GSM networks are:  horizontal separation  vertical separation

TYPICAL SPATIAL ANTENNA DIVERSITY CONFIGURATIONS

Horizontal Separation

Vertical Separation

THREE ANTENNA SPATIAL CONFIGURATION
10 Separation

Receive 1

Transmit

Receive 2

TWO ANTENNA SPATIAL CONFIGURATION
10 Separation

Tx Rx

Duplexer

Receive 2
Transmit Receive 1

POLARISATION DIVERSITY ANTENNA SYSTEMS • A single (say vertical) polarised electromagnetic wave is converted to a wave with two orthogonal polarised fields while it is propagating through scattering environment. • It has also been found that the two fields exhibit some extent of decorrelation.

DUAL POLARISED ANTENNAS • A dual-polarisation antenna consists of two sets of radiating elements which radiate or, in reciprocal, receive two orthogonal polarised fields. • The antenna has two input connectors which separately connects to each set of the elements. • The antenna has therefore the ability to simultaneously transmit and receive two orthogonally polarised fields.

H/V

Slant 45

ADVANTAGES OF DUAL POLARISED ANTENNAS • The best advantage of using the dual polarisation antenna is the reduction in the number of antennas per sector. • Reduced size of the headframe of the supporting structure • Reduced windload and weight. • Reduced difficulty in site acquisition and installation. • Cost saving – Requiring slim tower – Requiring less installation time. – Cost of one dual polarisation antenna is generally lower than that of two – Single polarised antennas

T R
DUAL POLE ANTENNA DUAL POLE ANTENNA

SINGLE POLE ANTENNA

TX RX RX RX TX RX T R
DUAL POLE ANTENNA

DUAL POLARISED ANTENNA CONFIGURATIONS

TX RX TX RX

T R

SYSTEM INFORMATION MESSAGES

BROADCAST MESSAGES • System information is data about the network which the MS needs to be able to communicate with the network in a appropriate manner. System information messages are sent on the BCCH and SACCH. There are six different types of system information messages. System information messages 1 to 4 are broadcast on the BCCH and are read by the MS in idle mode. System information message 5 and 6 are sent on the SACCH to the MS in dedicated mode. System information messages 1 to 4 are broadcast on the BCCH in a cyclic mode over 8 BCCH multiframes, i.e. 8 * 51 frames. Every message is sent at least after every 1.8 sec.

• • • • • •

BROADCAST MESSAGES
System Information 1 2 3 4 BCCH Multiframe 0 1 2 and 6 3 and 7

What is sent is optional on BCCH Multiframe 4 and 5 • • System information 5 and 6 are sent on the SACCH immediately after HO or whenever nothing else is being sent. Downlink SACCH is used for system information messages while Uplink SACCH is used for measurement reports.

SYSTEM INFORMATION 1 When frequency hopping is used in cell MS needs to know which frequency band to use and what frequency within the band it should use in hopping algorithm. Cell Channel Description Cell allocation number :- Informs the band number of the frequency channels used. 00 - Band 0 ( Current GSM band ) Cell allocation ARFCN :- ARFCN’s used for hopping. It is coded in a bitmap of 124 bits.
124 123 122 121

016 015 014 013 012 011 010 009 008 007 006 005 004 003 002 001

SYSTEM INFORMATION 1 RACH Control Parameters Access Control Class :- Bitmap with 16 bits. All MS spread out on class 0 - 9. Priority groups use class 11-15. A bit set to 1 barres access for that class. Bit 10 is used to tell the MS if emergency call is allowed or not. 0 - All MS can make emergency call.

1 - MS with class 11-15 only can make emergency calls.
Cell barred for access :0 - Yes

1 - No

SYSTEM INFORMATION 1 RACH Control Parameters Re-establishment allowed :0 – Yes 1 - No max_retransmissions :- Number of times the MS attempts to access the Network [ 1,2,4 or 7 ]. tx_integer :- Number of slots to spread access retransmissions when a MS attempts to access the system. Emergency Call Allowed :- Yes / No

SYSTEM INFORMATION 2 • Contains list of BCCH frequencies used in neighbor cells. • MS uses this list to measures the signal strength of the neighbors.

Neighbor Cell Description
BA Indicator :- Allows to differentiate measurement results related to different list of BCCH frequencies sent to the MS. BCCH Allocation number :- Band 0 is used.

BCCH ARFCN number :- Bitmap 1 -124
1 = Set 0 = Not set PLMN permitted

RACH Control Parameters

SYSTEM INFORMATION 3 Location Area Identity
8 7 6 5 4 3 2 1 Octet A Octet B Octet C Octet D Octet E Binary BCD

MCC DIG 2 1 1 1 1 LAC LAC MNC DIG 2

MCC DIG 1 MCC DIG 3 MNC DIG 1

Cell Identity
8 7 6 5 4 3 2 1 Octet F Binary Octet G

CI CI

SYSTEM INFORMATION 3 Control Channel Description Attach / Detach 0 = Allowed 1 = Not allowed cch_conf :- Defines multiframe struture
cch_conf Physical Channels Combined No of CCH 0 1 timeslot (0) NO 9 1 1 timeslot (0) YES 3 2 2 timeslots (0, 2) NO 18 4 3 timeslots (0, 2, 4) NO 27 6 4 timeslots (0, 2, 4, 6) NO 36

bs_agblk :- Number of block reserved for AGCH [ 0-7 ].
Ba_pmfrms :- Number of 51 frame multiframes between transmisiion of paging messages to MS of the same group. T3212 :- Periodic location update timer [ 1-255 deci hours].

SYSTEM INFORMATION 3 Cell Options dtx pwrc :- Power control on the downlink. 0 = Not used 1 = Used Radio link timeout :- Sets the timer T100 in the MS.

Cell Selection Parameters
Rxlev_access_min :- Minimum received signal level at the MS for which it is permitted to access the system. 0-63 = -110 dBm to -47dBm mx_txpwr_cch :- Maximum power the MS will use when accessing the system. Cell_reselect_hysteresis :- Used for cell reselection. RACH Control Parameters

SYSTEM INFORMATION 4 Location Area Identification Cell Selection Parameters

Rxlev_access_min
mx_txpwr_cch Cell_reselect_hysteresis RACH Control Parameters

max_retransmissions
tx_integer Cell barred for access Re-establishment allowed

Emergency Call Allowed
Access Control Class

SYSTEM INFORMATION 4 Channel Description Channel type :- Indi. channel type SDCCH or CBCH( SDCCH/8). Subchannel number :- Indicates the subchannel. Timeslot number :- Indicates the timeslot for CBCH [0 - 7]. Training Sequence Code :- The BCC part of BSIC[0 - 7 ]. Hopping Channel(H) :- Informs if CBCH channel is hopping or single. 0 - Single RF Channel 1 - RF hopping channel ARFCN :- If H = 0 MAIO :- If H = 1 , informs the MS where to start hopping. Values [0 - 63]. HSN :- If H = 1 , informs the MS in what order in what order the hopping should take place. Values [ 0 - 63]. HSN = 0 Cyclic Hopping. MA :- Indicates which RF Channels are used for hopping. ARFCN numbers coded in bitmap.

SYSTEM INFORMATION 5 Sent on the SACCH on the downlink to the MS in dedicated mode. Neighbour Cell Description BA-IND :- Used by the Network to discriminate measurements results related to different lists of BCCH carriers sent by the MS( Type 2 or 5). Values 0 or 1 ( different from type 2). BCCH Allocation number :- 00 - Band 0 (Current GSM band). BCCH ARFCN :- Neighboring cells ARFCN’s. Sent as a bitmap. 0 = ARFCN not used 1 = ARFCN used
124 123 122 121

016 015 014 013 012 011 010 009 008 007 006 005 004 003 002 001

SYSTEM INFORMATION 6 • MS in dedicated mode needs to know if the LA has changed. • MS may change between cells with different Radio link timeout and DTX. Cell Identity Location Area Identification Cell Options

dtx
pwrc Radio link timeout PLMN permitted

PAGING • Whenever the Network wants to contact the MS, it sends messages on the paging channel.

•
• • •

Paging is sent on the PCH and it occupies 4 bursts.
MS has to monitor the paging channel to receive paging messages. MS does not monitor all paging channel but only specific paging channels. There are three types of paging messages

Paging Type 1 2 3

No of MS using IMSI 2 1 -

No of MS using TMSI 2 4

Total no of MS 2 3 4

CALCULATION OF PAGING GROUP Following factors are used for calculation of paging group • CCCH_group

–
– –

cch_conf in System Information 3 defines the number of CCCH used in the cell.
CCCH can be allocated only TN 0, 2, 4, 6. Each CCCH carries its own paging group of MS.

–
• •

MS will listen to paging messages of its specific group.

bs_pa_mfrms bs_ag_blk_res

CALCULATION OF PAGING GROUP Total number of paging groups on 1 CCCH_GROUP(N) No of paging groups N = Paging blocks * Repitition of paging blocks

= [ CCCH - bs_ag_blk_res ] * bs_pa_mfrms
Range of Paging Groups on 1 CCCH_Group Minimum available Paging Groups = Min pag blocks * min bs_pa_mfrms

=2*2
=4 Maximum available Paging Groups = Max pag blocks * max bs_pa_mfrms =9*9 = 81

AVAILABLE PAGING BLOCKS ON 1 CCCH_GROUP Maximum AGCH reservation for non-combined multiframe = 7 Available paging blocks = 2 Maximum AGCH reservation for combined multiframe = 1 Available paging blocks = 2

Minimum AGCH reservation for non-combined multiframe = 0
Available paging blocks = 9 Minimum AGCH reservation for combined multiframe = 0

Available paging blocks = 3
No of paging blocks will have a range of 2 - 9

CALCULATION OF CCCH AND PAGING GROUP NO

CCCH_GROUP = [ ( IMSI mod 1000) mod (BS_CC_CHANS * N ) ] div N
Paging group no = [ ( IMSI mod 1000) mod (BS_CC_CHANS * N ) ] mod N

HANDOVER AND POWER CONTROL

HANDOVER • The GSM handover process uses a mobile assisted technique for accurate and fast handovers, in order to: – – • • • • Maintain the user connection link quality. Manage traffic distribution

•

The overall handover process is implemented in the MS,BSS & MSC. Measurement of radio subsystem downlink performance and signal strengths received from surrounding cells, is made in the MS. These measurements are sent to the BSS for assessment. The BSS measures the uplink performance for the MS being served and also assesses the signal strength of interference on its idle traffic channels. Initial assessment of the measurements in conjunction with defined thresholds and handover strategy may be performed in the BSS. Assessment requiring measurement results from other BSS or other information resident in the MSC, may be perform. in the MSC.

HANDOVER (Cont) • The MS assists the handover decision process by performing certain measurements.

•

When the MS is engaged in a speech conversation, a portion of the TDMA frame is idle while the rest of the frame is used for uplink (BTS receive) and downlink (BTS transmit) timeslots.
During the idle time period of the frame, the MS changes radio channel frequency and monitors and measures the signal level of the six best neighbor cells. Measurements which feed the handover decision algorithm are made at both ends of the radio link.

•

•

MS END • At the MS end, measurements are continuously signalled, via the associated control channel, to the BSS where the decision for handover is ultimately made. • MS measurements include: –Serving cell downlink quality (bit error rate (BER) estimate). –Serving cell downlink received signal level, and six best neighbor cells downlink received signal level. • The MS also decodes the Base Station ID Code (BSIC) from the six best neighbor cells, and reports the BSICs and the measurement information to the BSS.

BTS END • The BTS measures the uplink link quality, received signal level, and MS to BTS site distance.

•
• •

The MS RF transmit output power budget is also considered in the handover decision.
If the MS can be served by a neighbor cell at a lower power, the handover is recommended. From a system perspective, handover may be considered due to loading or congestion conditions. In this case, the MSC or BSC tries to balance channel usage among cells.

MS IDLE TIME REPORTING • During the conversation, the MS only transmits and receives for one eighth of the time, that is during one timeslot in each frame.

•

During its idle time (the remaining seven timeslots), the MS switches to the BCCH of the surrounding cells and measures its signal strength.
The signal strength measurements of the surrounding cells, and the signal strength and quality measurements of the serving cell, are reported back to the serving cell via the SACCH once in every SACCH multiframe. This information is evaluated by the BSS for use in deciding when the MS should be handed over to another traffic channel.

•

•

•

This reporting is the basis for MS assisted handovers.

MEASUREMENT IN ACTIVE MODE
Downlink
0 1 2 Frame 24 3 4 5 6 7 0 1 2 Frame 25 3 4 5 6 7 0 1 2 Idle Frame 3 4 5 6 7 0 Frame 0 1 2

1

2

3

1

2

4

1

2

0

1

2

3

4

5

6

7

0

1

2

3

4

5

6

7

0

1

2

3

4

5

6

7

0

1

2

Uplink

Frame 24

Frame 25

Idle Frame

Frame 0

1. 2. 3. 4.

MS receives and measures signal strength on serving cell(TS2). MS transmits MS measures signsl strength for at least one neighbor cell. MS reads BSIC on SCH for one of the 6 strongest neighbor.

NUMBER OF NEIGHBORS • Maximum 32 averaging of RSS takes place. • • Practically a cell neighbors can be equipped for a cell. If high numbers of neighbors are equipped, then the accuracy of RSS is decreased as should have 8 to 10 neighbors.
T T T T T T T T T T T T S T T T T T T T T T T T T I 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 T T T T T T T T T T T T S T T T T T T T T T T T T I 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 T T T T T T T T T T T T S T T T T T T T T T T T T I 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 T T T T T T T T T T T T S T T T T T T T T T T T T I 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

NUMBER OF NEIGHBORS • In one SACCH multiframe there are 104 TDMA frames. • • • Out of this 104 frames 4 frames are idle and are used to decode the BSIC. Remaining 100 TDMA frames are used to measure RSS( Received Signal Strength) of the neighbor. If 25 neigbors are equipped, then in one SACCH multiframe each neigbor is measured 100/25 = 4 times and averaged out. This produces a less accurate value. If 10 neigbors are equipped, then in one SACCH multiframe each neigbor is measured 100/10 = 10 times and averaged out. This produces a more accurate value.

•

INTERFERENCE ON IDLE CHANNEL • GSM causes its own time interference. • The MS has a omni-directional antenna. Much of the MS power goes to the server but a lot is interfering with surrounding cells using the same channel. The TDMA frames of adjacent cell are not aligned since they are not synchronised. Hence the uplink in the surrounding cell suffers from interference.

•

Channel 10 Cell 1

Channel 10 Cell 2

INTERFERENCE ON IDLE CHANNEL • The BSS keeps on measuring the interference on the idle timeslots. • • • • Ambient noise is measured and recorded 104 times in one SACCH multiframe. These measurements are averaged out to produce one figure. The BSS then distributes the idle timeslots into band 0 to band 5. Since the BSS knows the interference level on idle timeslots, it uses this data to allocate the best channel first and the worst last.
Inteference on idle channel measured on Idle Timeslot by BSS

0

1

2

3

4

5

6

7

HANDOVER The following measurements is be continuously processed in the BSS : i) Measurements reported by MS on SACCH - Down link RXLEV - Down link RXQUAL - Down link neighbor cell RXLEV ii) Measurements performed in BSS - Uplink RXLEV - Uplink RXQUAL - MS-BS distance - Interference level in unallocated time slots Every SACCH multiframe (480 ms) a new processed value for each of the measurements is calculated..

HANDOVER CONDITIONS Handover is done on five conditions – Interference – RXQUAL – RXLEV – Distance or Timing Advance – Power Budget Interference - If signal level is high and still there is RXQUAL problem, then the RXQUAL problem is because of interference. RXQUAL - It is the receive quality. It ranges from 0 to 7 , 0 being the best and 7 the worst RXLEV - It is the receive level. It varies from -47dBm to -110dBm. Timing Advance - Ranges from 0 to 63. Power budget - It is used to save the power of the MS.

HANDOVER TYPES Intra-Cell Handover

BSC

0

1

2

3

4

5

6

7

BTS

Call is handed from timeslot 3 to timeslot 5

• • •

Handover takes place in the same cell from one timeslot to another timeslot of the same carrier or different carriers( but the same cell). Intra-cell handover is triggered only if the cause is interference. Intra-cell handover can be enabled or disabled in a cell.

HANDOVER TYPES Intra-BSC Handover

BSC1
0 1 2 3 4 5 6 7

BTS1
Call is handed from timeslot 3 of cell1 to timeslot 1 of cell2 . Both the cells are controlled by the same BSC.

0

1

2

3

4

5

6

7

•

Handover takes place between different cell which are controlled by the same BSC.

HANDOVER TYPES Inter-BSC Handover

BSS1
0 1 2 3 4 5 6 7

BTS1 MSC

Call is handed from timeslot of cell1 to timeslot 1 of cell2 Both the cells are controlled by the different BSC.

BSS2

0

1

2

3

4

5

6

7

BTS2

•

Handover takes place between different cell which are controlled by the different BSC.

HANDOVER TYPES Inter-MSC Handover

MSC1

BSS1
0 1 2 3 4 5 6 7

BTS1

Call is handed from timeslot 3 of cell1 to timeslot 1 of cell2 . Both the cells are controlled by the different BSC, each BSC being controlled by different MSC

MSC2

BSS2

0

1

2

3

4

5

6

7

BTS2

•

Handover takes place between different cell which are controlled by the different BSC and each BSC is controlled by different MSC.

MEASUREMENT REPORT PROCESSING
Measurement report sent every 480ms 1st MR 2nd MR 3rd MR 4th MR 5th MR 6th MR

Average Average Average Average

• • • •

Measurement reports are sent to the BSS on the downlink every 480ms. Similarly the BSS measures the uplink level and quality. These reports are averaged out according to setting of factors hreqave and hreqt. Each averaged value is called a N.

POWER CONTROL BSS • Power control by BSS is based on the measurement report sent by the MS. • Averaging mechanism is used to produce N. The number of measurement reports to be averaged depends on the values 0 -110 dBm hreqave. N and P values as well as 10 -100 dBm hreqave has to be set by the operator. P out of N averages must exceed thershold. N1 & P1 values are used for power increase and N2 & P2 values for power decrease . A window has to be created by setting the upper level
20 l_rxlev_dl_p = 25 30 u_rxlev_dl_p = 35 40 -90 dBm -85 dBm -80 dBm -75 dBm -70 dBm

•

• •

•

63

-47 dBm

POWER CONTROL BSS Lower level threshold = 25 Upper level threshold = 35 Power increase N1 = 5 P1 = 3 Power decrease N2 = 4 P2 = 3
l_rxlev_dl_p = 25 -85 dBm Do nothing u_rxlev_dl_p = 35 -75 dBm Decrease Power
3 N below threshold So power is decreased by the BSS Only 2 N above threshold So no increase of power

0

-110 dBm

Increase Power

-60 dBm 63 -47 dBm

N considered for power increase N considered for power decrease

POWER CONTROL BSS bts_P_Con_INTERVAL : Minimum interval between changes in the RF power level. Range 0 - 30 steps, size 0.96s. Pow_Incr_Step_Size Pow_Red_Step_Size BS_TXPWR_MAX : Range 2, 4 or 6 dB. : Range 2 or 4 dB. : Maximum TXPWR used by the BSS.

POWER CONTROL MS • Power control by MS is based on the measurements taken by the BSS. • Averaging mechanism is used to produce N. The number of measurement reports to be averaged depends on the values hreqave. N1 & P1 and N2 and P2 values that are used by BSS for power control are also applicable to the MS. P out of N averages must exceed threshold. A window has to be created by setting the upper level and lower level thresholds u_rxlev_ul_p and l_rxlev_ul_p.
l_rxlev_ul_p = 20 0 -110 dBm P1 out of N1 Increase Power -90 dBm -85 dBm u_rxlev_ul_p = 30 -80 dBm

•

• •

P2 out of N2 Decrease Power 63 -47 dBm

POWER CONTROL MS Lower level threshold = 20 Upper level threshold = 30 Power increase N1 = 5 P1 = 3 Power decrease N 2= 4 P2 = 3
u_rxlev_ul_p = 30
Only 2 N below threshold So no power is decreased the MS 3 N above threshold So Power is increased by the MS

0

-110 dBm

Increase Power

l_rxlev_ul_p = 20

-90 dBm Do nothing -80 dBm Decrease Power -60 dBm 63 -47 dBm

N considered for power increase N considered for power decrease

POWER CONTROL MS ms_P_Con_INTERVAL : Minimum interval between changes in the RF power level. Range 0 - 30 steps, size 0.96s. Pow_Incr_Step_Size Pow_Red_Step_Size MS_TXPWR_MAX : Range 2, 4 or 6 dB. : Range 2 or 4 dB. : Maximum TXPWR a MS may use in the serving cell. Range (13, 43 dBm); step size 2 dB.

POWER CONTROL -RXQUAL • The MS and BSS also measure the downlink and uplink quality respectively. • • The RXQUAL measurements are averaged and compared against upper and lower thresholds set in the database. N and P voting mechanism is used to determine if power increase or decrease is required on not. HO on RXQUAL is done only if the MS or BSS is at full power.
0 0.14% P4 out of N4 decrease Power u_rxqual_ul_p u_rxqual_dl_p 2 3 l_rxqual_ul_p l_rxqual_dl_p 4 0.57% 1.13% 2.26% P3 out of N3 Increase Power 6 7 9.05% 18.10%

•

HANDOVER - RXLEV • If an MS is moving out of a cells coverage area then RXLEV and RXQUAL measurements will cause the BSS and MS to increase their power output. • • This process continues till the MS reaches its maximum permitted output power and then handover is required. N5 and P5 values are used in voting mechanism for RXLEV handover. P out of N averages must exceed thershold. l_rxlev_ul_h, l_rxlev_dl_h, are the thresholds set in the database by the operator.
l_rxlev_ul_h l_rxlev_dl_h 20 l_rxlev_ul_p l_rxlev_dl_p 30 u_rxlev_ul_p u_rxlev_dl_p 40 -90 dBm -85 dBm -80 dBm -75 dBm -70 dBm 0 -110 dBm

10

-100 dBm

• •

63

-47 dBm

HANDOVER - RXQUAL • If an MS is moving out of a cells coverage area then RXLEV & RXQUAL measurements will cause the BSS & MS to increase their power output. • • This process continues till the MS reaches its maximum permitted O/P power and then handover is required. N6 and P6 values are used in voting mechanism for RXQUA; handover. P out of N averages must exceed thershold. l_rxqual_ul_h, l_rxqual_dl_h, are the thresholds set in the database by the operator.
l_rxqual_ul_p l_rxqual_dl_p l_rxqual_ul_h l_rxqual_dl_h u_rxqual_ul_p u_rxqual_dl_p 0 0.14%

• •

2

0.57%

4

2.26% Adjust Power

6 7

2.26% 9.05% 18.10%

HANDOVER - INTERFERENCE • If the RXQUAL of either the U/L or D/L reaches the threshold that would normally cause a HO but the RXLEV is at a value higher than the threshold requiring a power increase then a HO may be initiated due to interference. This type of handover is always intra_call Handover. • N7 and P7 are set for the voting mechanism.
0 Quality -110 dBm

u_rxqual_ul_p u_rxqual_dl_p

0

0.14%

10

-100 dBm

l_rxlev_ul_ih l_rxlev_dl_ih

2
20 -90 dBm

0.57%

30 Interference 40 -70 dBm

l_rxqual_ul_p l_rxqual_dl_p l_rxqual_ul_h l_rxqual_dl_h

4

2.26% Adjust Power

6 7

2.26% 9.05% 18.10%

63

-47 dBm

HANDOVER - MS DISTANCE • As the MS moves away from BSS, the BSS calculates the timing advance and instructs the MS to transmit earlier to compensate for the propagation delay. The maximum timing advance is upto 63 bits. The MS_RANGE_MAX field can be set to any one of these 63 values thus determining the cell radius. As soon as the MS exceeds the MS_RANGE_MAX, a “handover recognised” message is generated. The interval between timing advance changes is determined by the timing_advance_period field. It has a range of 0-31, each step being a SACCH multiframe. N8 and P8 are used in the voting mechanism.

• • • •

•

POWER BUDGET • This assessment process is employed by the network as a criterion in the hand-over process, by setting a flag in the BSS by O&M command. • If the process is employed, every 480 ms, for every connection and for each of allowable 16 adjacent cells, the BSS evaluates the following expression : PBGT(n) = (Min(MS_TXPWR_MAX,P) - RXLEV_DL - PWR_C_D) - (Min(MS_TXPWR_MAX(n),P) - RXLEV_NCELL(n)) Where the values of RXLEV_NCELL(n) and RXLEV_DL are obtained with the averaging processes defined above. PWR_C_D is the diff between the max D/L RF power permitted in the cell & the actual D/L power due to the BS power control. MS_TXPWR_MAX is the maximum RF TXPWR an MS is permitted to use on a traffic channel in the serving cell. MS_TXPWR_MAX (n) is the maximum RF TXPWR an MS is permitted to use on a traffic channel in adjacent cell n. P is the maximum TXPWR capability of the MS.

HANDOVER PROCEDURE • The network initiates the hand-over procedure by sending an HANDOVER COMMAND message to the Mobile Station on the main DCCH. • The NETWORK then starts timer T3103. • T3103 guards against the receipt of either the unsuccessful message from the source cell or successful message from the target cell. The receipt of either message stops this timer. • If this timer expires then a CLEAR REQUEST will be sent to the MSC in a bid to clear the connection. • The HANDOVER COMMAND contains all the data related to the target cell like BCCH ARFCN, NCC, BCC, Timeslot Number, Training sequence code, Power level to be used, Handover reference number etc.

•
•

The MS sends HANDOVER ACCESS burst with the same referance number and starts timer T3124.
The MS sends Handover access bursts and waits for a PHYSICAL INFORMATION from the Network.

HANDOVER PROCEDURE • When the Network sends the PHYSICAL INFORMATION message timer T3105 is started by the network. • If T3105 expires before the correct response from the MS has been received, T3105 is reset and the PHYSICAL INFORMATION message is repeated. This process is repeated a number of times until either the MS correctly responds or the maximum number of repititions(NY1) is reached. If the maximum number of repetitions is reached the newly allocated channels are release and the handover abandoned. On the MS side if the timer T3124 expires, then the MS deactivates the new channel, reactivates the old channel and if it is successful sends a HANDOVER FAILURE message on the old channel and the call continues. The value of T3124 is set to 320ms. (It must be lower than Ny1 times T3105 for proper functions.)

•

• •

•

HANDOVER PROCEDURE • The timer T3105 can be set from 20 - 60 ms. • If timer T3103 expires before either the HAND-OVER COMPLETE message is received on the new channels, or a HAND-OVER FAILURE message is received on the old channels, or the MS has re-established the call, the old channel is released.
TIMER T3103
MS SOURCE CELL INITIATE HANDOVER HANDOVER COMMAND NETWORK START TIMER T3103

HANDOVER FAILURE UNSUCCESSFUL HANDOVER TARGET CELL HANDOVER COMPLETE HANDOVER SUCCESSFUL STOP TIMER T3103 EXPIRED STOP TIMER T3103 EXPIRED

HANDOVER PROCEDURE
TIMER T3105
SOURCE CELL HANDOVER COMMAND HANDOVER ACCESS MS TARGET CELL

HANDOVER ACCESS

PHYSICAL INFORMATION

START TIMER T3105 EXPIRED

HANDOVER COMPLETE IF HO COMPLETE MSG STOP TIMER T3105 EXPIRED PHYSICAL INFORMATION IF NO HO COMPLETE MSG AND T3105 EXPIRES SEND PHYSICAL INFO AND START TIMER T3105 NY1 TIMES If NY1 = 0 HANDOVER FAILURE TO BSC

HANDOVER COMMAND Sent by the source cell to the MS • Cell Description

NCC
BCC BCCH ARFCN • Channel Description

Channel Type - TCH/F + ACCH
Timeslot Number TSC Hopping Channel - Single RF Channel

ARFCN
• • Handover Reference Number Power level

HANDOVER ACCESS Sent by the MS to the target cell on FACCH Handover Reference Number

PHYSICAL INFORMATION Sent by the Target cell to the MS Timing Advance Value

OPTIMIZATION PROCESS

NEED FOR OPTIMISATION • Optimisation is an invaluable element of service required to maintain and improve the quality and capacity of a network. • It is essential if an operator wants to implement changes to the network to maintain the high quality of service levels expected by subscribers in networks. Without optimisation the network will degrade from the commissioned state, due to the network changing radically as the traffic on the system grows, and snapshot optimisation will not keep pace with these changes. Without optimisation the system will suffer poor call quality, many dropped calls due to interference and inaccurate parameters resulting in poor handover performance. These together with other problems, have the same result, Subscriber Dissatisfaction.

•

•

•

INPUTS

TOOLS

Output

Quality Of Service Metrics RF Design Parameters

Drive test kit(TEMS) and optimization tool( PLANET) OMC-R or Traffic Analysis Tool(Metrica) OMC-R Customer Care Centre Database

Alarms and events Analysis from OMC
Drive testing Customer complaint Analysis Database Parameters

1) Frequency 2) BCCH changes 3) BSIC changes 4) Antenna downtilt 5) Azimuth changes 6) Antenna type changes 7) Database parameters changes 8) Handover algorithm tunings

INPUTS
• The following inputs are considered for optimisation: – QOS Parameters

–
– – –

RF Design Parameters
OMC alarms Routine Drive Testing Customer feedback

–
•

Database Parameters

Using the above inputs we can determine the optimization requirement and the the area which needs to be optimized.

QOS PARAMETERS • QOS Parameters are the quality indicators of the Network. • • • Call Success rate, Call Drop Rate, Handover success rate, Call Congestion are some of the QOS parameters. These parameters have to be continually monitored on cell, site , BSC and Network basis. If any abnormality is observed or if any deterioration is seen in any of the parameters optimization process has to be initiated.

RF DESIGN PARAMETERS • • When a Network is designed benchmarking is done for Network quality, capacity, failure and congestion parameters. Whenever the Network is unable to comply with any of the RF design parameters, optimization process needs to be initiated.

OMC ALARMS • • Any problem in the Network results in a alarm at the OMC. Whenever a alarm is observed at the OMC it must be carefully analyzed to determine if there is a network problem and if it is required to initiate optimization process. The alarm can be due to faulty hardware which can create problems in the network.

•

DRIVE TESTING • Drive testing is done continually to monitor the health of the network. • • • It is a normal procedure to define drive test routes and have them drive tested daily to monitor the network. All sites and sectors should be tested within the drive test routes at least once. Following care should be taken while defining the routes – All major roads and highways should be tested at least twice per week within the agreed routes. – All cells should be tested for handout and hand-in within the routes if possible. – The routes should be approximately 2 - 3 hours in duration. This is required to manage the data collected for analysis, routes longer than this can be difficult to analyze and transfer from P.C to P.C due to the files being too large. – Routes of major importance should be identified prior to starting and should be driven first. i.e. Airports to the city centre.

CUSTOMER FEEDBACK • A procedure to feed back customer information on the performance and coverage of the network can be extremely useful. The received information is used to target areas requiring optimisation and to verify coverage against the RF design. The information fed back is also used in assessing the growth of the network by identifying areas of high traffic volumes.

• •

Other Networks

OPTIMIZATION PROCESS

OPTIMIZATION PROCESS • Once the optimization needs have been identified the optimization process is started to analyze the problem and then provide possible solutions. • Optimization process involves studying and analyzing the problems using the following steps – Statistical Analysis

– Drive testing
– OMC tools – Site visits

STATISTICAL ANALYSIS • The quality of the network can be measured through the statistics generated from the network.

•
•

These are available through the OMC (Operations and Maintenance Center) and are used to generate key metrics.
This operational metrics will then be measured against the required metrics as agreed between the operator and vendor, from this comparison an optimization plan will be generated. Drive test statistics represent a small sample of the total calls on the network and can provide a useful indication of network quality. In order to provide a precise information of user traffic, the statistics obtained from the whole network through the OMC are a more accurate assessment of the quality of the network.

• •

KEY QUALITY METRICS The following metrics can be used to measure the performance of the network. • • • Dropped Call Rate Handover Success Rate Overall RF Loss Rate - TCH & SDCCH RF loss combined

•
• • •

TCH Assignment Success Rate
Call Success rate TCH Blocking Rate SDCCH Blocking

IMPORTANCE OF STATISTICAL ANALYSIS • It is important for a good optimization engineer to have good knowledge of various statistics available from performance management. • • Any change in the network whether good or bad is definitely reflected in the statistics. By studying and analyzing the statistics we can not only detect the problems in the network but in some cases even provide the solution for the problem.

STATISTICAL ANALYSIS TYPES • Statistical Analysis can be divided into two categories – Trend Analysis – Daily Analysis

TREND ANALYSIS • Analysis which is carried out using statistical data over a period of time is called trend analysis.

•
• • • •

The longer the period better the analysis and accurate the results.
Trend analysis helps us in understanding the performance of the Network over a period of time. It is important in generating Network Performance report and helps us to understand the progress of the network. It also helps us in Network expansion planning. It is expected that the operator maintain at least six months of data.

09 JU

Percentage (%)

TREND ANALYSIS

10

15

20

25

0

5

Breakdown of Call Setup Failures

Date and Time

L1 99 09 9: JU 00 L1 :0 0: 99 12 00 9: JU 12 L1 :0 0: 99 12 00 9: JU 00 L1 :0 0: 99 13 00 9: JU 12 L1 :0 0: 99 13 00 9: JU 00 L1 :0 0: 99 14 00 9: JU 12 L1 :0 0: 99 14 00 9: JU 00 L1 :0 0: 99 15 00 9: JU 12 L1 :0 0: 99 15 00 9: JU 00 L1 :0 0: 99 16 00 9: JU 12 L1 :0 0: 99 16 00 9: JU 00 L1 :0 0: 99 19 00 9: JU 12 L1 :0 0: 99 19 00 9: JU 00 L1 :0 0: 99 20 00 9: JU 12 L1 :0 0: 99 20 00 9: JU 00 L1 :0 0: 99 00 9: 12 :0 0: 00

SDCCH RF Loss Rate (%) SDCCH RF Blocking Rate (%) MSC/PSTN-Related Failures TCH Assıgn Faılures TCH RF Blockıng Rate (%)

DAILY ANALYSIS • • Key statistics are analyzed on a daily basis for the Network, BSC‟s and cells. If any problem is observed (e.g. RF losses for a particular cell has gone up drastically) the concerned statistics are analyzed in detail to determine the problem and then to initiate appropriate action. Daily performance analysis helps us check and solve problems at the initial stage itself and thus help us to maintain the quality of the Network.

•

DAILY ANALYSIS

STATISTICS EVALUATION PROCESS • Analyze key statistics for cell wise data. • • • • • • • Note down the problems and prioritize them. Evaluate the concerned statistics in detail to pinpoint the possible cause for the problems. Initiate appropriate action to determine the solution. Apply the solution. Check statistics for improvement. If no or little improvement repeat steps 3,4,5 and 6. Same process can be applied for BSC wise and Network data.

STATISTICS EVALUATION PROCESS(Eg) • SDCCH and TCH congestion • • • • This statistics tell you if your TCH and SDCCH were congested To check if it is required to add a new carrier we must look at these statistics but should also look at time congestion statistics. These statistics tell you the amount of time for which the cell was congested during the day. Also it is important to study the trend for the above statistics before the action to be taken is decided.

STATISTICS EVALUATION PROCESS(Eg)
SITE NAME Mehta_Mahal / 2 City_View / 2 Fatimabai / 3 Sanskriti / 2 New_Purshottam / 1 Shambhov Tirth / 1 Daya_Mandir / 3 Daya_Mandir / 2 Al_Hassan / 1 Family_House / 2 Shah_&_Nar / 1 Karolia / 2 Hong_Kong_Bank / 2 Vijaydeep / 1 Modi_Sadan / 3 Gokul / 2 Shah_&_Nar / 3 Fatimabai / 2 Jimmy_Tower / 1 City_View / 1 Mangal_Kunj / 1 Aangan / 2 Samson / 2 Shabnam / 2 Sai_Shakti / 2 Garden_View / 1 Meenal / 3 Samrat / 3 NOC BBH ERLANG MAX MIN AVG ERL ERL ERL 18.79 3.86 15.64 13.41 2.13 4.16 12.87 2 4.16 18.27 6.62 10.64 10.96 4.6 7.57 18.75 6.31 11.14 9.4 2.03 7.53 9.47 1.53 7.03 10.73 2.57 6.83 10.42 4.27 7.08 5.65 1.12 2.81 4.25 2.13 3.21 17.96 0.1 10.41 10.74 0.2 6.36 10.68 4.47 7.19 4.25 2.52 3.21 11.77 1.27 4.32 4.55 1.68 2.34 7.68 6.27 7.08 5.27 0.48 1.95 4.34 2.45 3.34 8.83 4.36 6.85 8.37 4.77 7.27 8.13 5.41 6.76 3.24 1.95 2.52 3.84 2.77 3.24 3.36 1.65 2.42 11.21 3.27 6.25 MAX CC(%) 26.12 60.98 47.76 21.8 30.53 24.23 14.58 10.49 22.62 17.55 31.84 18.64 10.7 7.69 17.66 13.78 21.49 25.45 15.37 38.81 15.15 10.34 3.67 11.62 18.24 10 32.47 12.13 ASSOC TC(Min) 8.58 18.47 13.98 6.85 6.11 7.25 1.99 1.11 3.71 4.30 9.72 4.19 3.56 2.58 5.25 2.71 7.22 9.10 2.47 9.08 2.94 2.30 0.58 1.88 1.59 2.41 4.99 3.78 MAX TC(Min) 8.58 18.47 13.98 6.85 6.11 7.25 1.99 1.88 4.24 4.30 9.72 4.19 3.56 2.58 5.25 2.71 7.22 9.10 2.47 9.08 3.36 2.30 0.69 1.88 1.86 2.41 4.99 3.78 ASSOC TCR CC(%) DUE TO CONG 26.12 2358 60.98 977 47.76 972 21.80 788 30.53 624 24.23 605 14.58 434 5.14 385 13.86 376 17.55 366 31.84 263 18.64 216 10.70 213 7.69 198 17.66 192 13.78 192 21.49 178 25.45 169 15.37 163 38.81 150 10.27 144 10.34 140 2.89 133 11.62 130 17.24 126 10.00 121 32.47 116 12.13 109 TOTAL TC (Secs) 12744.22 2003.18 2450.05 1368.21 2634.69 1631.28 1725.82 1505.39 1805.64 1740.64 2806.01 4085.14 558.55 1162.80 1135.75 3610.17 804.76 2802.07 892.84 1147.30 2078.39 786.89 874.83 769.82 1560.60 2718.05 2823.42 675.43 REMARK

3 2 2 3 2 3 2 2 2 2 1 1 3 2 2 1 1 1 2 1 1 2 2 2 1 1 1 2

Congestion relief under trial Under observation " Add carrier Use congestion relief " Add carrier "

Add carrier " Under observation " Add carrier " " Under observation " Add carrier Add carrier Under observation " " Add carrier " "

Other Networks

DRIVETESTING

General • • • • Drive testing involves driving in a vehicle and collecting network data by making a lot of calls. The data collected includes data for serving cell as well as the neighbors. This data collected helps us to find and analyze the problems in the network. These data can also be loaded on the planning and optimization tools like Pegasos, Planet etc. and usefull plots can be generated such as serving cells coverage plots, Quality plots etc. Equipment Necessary for Drivetesting. – Vehicle

•

– Drive test mobile phone (e.g.Ericcson TEMS)
– External vehicle mounted GPS – Laptop with drive test software and GPS connection capability.

Drive test Outputs • Using the drive test equipment we can monitor the following

–
– – –

Status Information
Error reports Mode reports Layer 2 messages

–

Layer 3 messages

Status Information • In status information we get the following information – General Information: This includes the Latitude ,longitude data, server call name, Marker ,data, time , log file name etc. – Serving cell: This includes Cell Identity, BSIC, ARFCN ,MCC, MNC, LAC. – Serving + Neighbor cell data: This includes CI, BSIC, ARFCN, Rxlev, C1 and C2 for the serving and the best 6 neighbors. – Dedicated channel: This includes data such as Channel number, Timeslot number, Channel type and TDMA offset,hopping information and channel mode.

– Radio Environment: This includes serving cell,lat , long, rxlev, rxqual, TA, DTX and RL Timeout counter information.

Error reports • If any errors are reported during the call they can be analyzed from this report.

Mode reports • These are the channel mode reports.

Layer 2 messages • All the layer 2 messages can be analyzed.

Layer 3 messages • All the layer 3 messages can be analyzed.

Drive test types: • Drive test can be categorized in three types

–
– –

Routine drive test
Problem specific drive test Cell coverage analysis drive test

Routine drive test • As we have discussed earlier optimization is a ongoing process and the network needs to be monitored on a daily basis.

•
•

Routine drive test forms a integral part of this process.
Drive test routes are decided by the Network operator and these routes are regularly drive tested and any problems found are reported.

•
• • • •

These problems are then further analyzed and solved.
Hence it is important that these drive test routes are selected carefully. Drive test routes should include all the major road, important location, airports etc. Also they should be able to cover most of the cells. Each drive test route should be typically 2 - 3 hours long.

Typical Optimization Process using routine drive testing • The drive test routes must be decided by the operator and a priority set on the routes for testing.

•
•

The drive test routes are usually 2 - 3 hours in duration in order to ensure that the data generated is of a manageable size.
The drive test teams use the Test Mobile equipment (e.g.TEMS) to make test calls to the MSC test number on the network of 2 minute duration with a 15 second break. All data is logged on the computer, location information is also taken using a GPS receiver. During or after completion of the drive test route, analysis of the data collected is performed to identify areas of dropped or noisy calls. This will be done using FICS or other similar software.

• •

•

•

•

•
• •

•

Should the analysis of the route indicate problems of either dropped or noisy calls then with the aid of the RF design and Database parameters, an assessment is made to identify the possible source of interference causing the noisy or dropped call. If a call is dropped and no interference is present a retest is made in the same area, if the scenario of the dropped call can be repeated, the identity of the problem cell will be obtained and corrective action taken. To assist in confirming possible sources of interference there may be a requirement to remove the suspected interfering channel. This would be done by the optimisation engineers. The suspected interfering carrier would be removed temporarily from service and test calls made again in the problem area, this would show if the interference had been removed. The process for temporarily removing carriers would have to be agreed with the operator, this usually varies as to the importance of the cell as to what time of day it can be taken out of service.

•

• •

• •

•

•

After conformation as to what is causing the problem with the drive test route, the drive test engineer will attempt to find a solution to the problem. This can be one of a number of possibilities i.e. Power Change to BTS, Frequency Plan change, Neighbor addition required, etc. Once a possible solution to the problem has been found it may be possible in some circumstances to immediately attempt the solution via the OMC, this usually relates to minor database changes and adding neighbors. The solution is implemented and proven immediately. If the problem is rectified the change remains in place and a change request is raised for the solution for the purpose of keeping records of all changes in the network. If the solution requires a major database change or antenna work a change request must be raised via the Optimization Control Engineers. After the solution is implemented a retest of the problem area is carried out to confirm the problem has been solved

Problem drive testing • Any problem reported by statistical analysis, routine drive testing, customer care centre , alarms need to be analyzed in detail to find a solution. • Problem specific drive testing is a important tool which helps us do it. • Here we make a list of problematic cell and drive test them thoroughly to analyze the problem. • There may be many different methods which a optimization engineer may employ for the analysis. • As an example, if a particular cell is being interfered the frequency of the cell may be changed temporarily to identify the interferer. • Also the levels and TA at which the cell is being interfered may be analyzed. • Here the data collection and analysis are done simultaneously.

Cell Coverage Analysis Drive Test • It has been found that normally that the coverage and server area of the cells differ from the planned area. • Hence it is often found that new cells that come on air serve far more or much less area than initially planned and same could be the case with the coverage. • This could lead to two problems. If the server area is less than planned it could lead to coverage holes or poor cover areas. If the coverage area is more than planned it may cause interference in the network. • Hence it is important that once new cells come on air they must be thoroughly drive tested to determine their server and coverage areas. • If any major deviation from the initially planned design is found the cell sites should be optimized.

Scanning • This is a important feature of the drive test software. • It enables us to lock onto a particular frequency during the drive test which is helpful in determining the server area of a cell. • Also we scan a set of frequencies and have a graphical display of the same or can also be stored for further analysis. • This is helpful in finding interfering frequencies and also in finding clear frequency.

Optional Features • Some drive test equipment provide supplementary features which help during drive test. • Map displaying the drive tested area showing the major roads, location, cell sites is provided ,this helps us to be always aware as to where we are in the network. • Also some vendors provide spectrum analyzer which helps in finding the interfering frequencies and to find clear frequencies.

Typical Information Available From A Drive Test Tool

Graphical Representation

General Information Obtained During Drive Test

Layer2 and Layer3 Information Obtained During Drive Test

Layer3 Information Obtained During Drive Test

Layer3 Information Obtained During Drive Test

Layer3 Information Obtained During Drive Test

Layer3 Information Obtained During Drive Test

Serving Cell and Neighboring Cell Information

Radio Environment Information

Dedicated Channel Information

Other Networks

OMC TOOLS

General • Many vendors provide advanced tools which help in optimization of the Network.

•

Some vendors provide Network Health reports which provide you list of bad performing sites with poor sites and possible causes for the problems.
However one powerful tool provided by all operators is the call trace tool. The degree to which this feature has been developed varies from vendor to vendor. This is perhaps the most important tool in optimization. We will be having a look at this feature in detail.

• • •

Call Trace Feature • This feature enables us to put a trace on a call and collect all data related to the call.

•
•

The call trace can be put on a cell basis, BTS wise, over the BSC or over the entire Network.
Call trace can be put on a IMSI, IMEI ,TMSI or on every nth call being made in the cell, BTS, BSC or the Network.

•
• •

Call trace gives you all the information that you get in the drive test plus it also give you uplink Rxlev and Rxqual information.
Also drive testing can be done only on the roads hence it becomes difficult to locate and solve indoor problems. Since in call trace we can accumulate data for call being made throughout the cell it includes the indoor calls also and hence gives us the the correct picture regarding the performance of the cell.

Protocol Analyzer : • • Protocol analyzer may be used to analyze the C7 signaling messages between the MSC and the BSC . These are used to analyze problems which may originate either in the Radio part or the MSC e.g. paging problems.

SITE VISIT

General • When we visit the problematic site for optimizing we must ask three simple questions which will help us in optimizing 1. Why was this site put up? 2. Will this site serve that purpose ? 3. What are the problems that I see at this site and how can I solve them ? Let us now look at each of those questions individually.

•

Why was this site put up ? • • We must know if the site was installed for capacity or coverage. If it was for capacity we should know if it should offload the traffic of some existing sites and if it should generate traffic of its own. Also if the site in question is a hotspot or not. If the site was installed for coverage we should know exactly the area it is supposed to cover and if there is some existing coverage in that area.

•

Will this selected site serve that purpose ? • • Once we are clear about the objective of installing the site we must analyze if the site in question serves that purpose or not. It is important that the selected site serves its objective.

What are the problems and how can I solve them • Some of the common problems could be as follows – The neighboring sites cause interference to the proposed site. – The site is a cause of interference to some existing sites. – If there is a possibility of a backlobe or sidelobe problem. – There could be some near end obstruction

Other Networks

OPTIMIZATION SOLUTIONS

General • Once the problem has been analyzed a solution has to be provided. Common solution to problems are

– Database Parameters Changes
– Antenna Optimization – Frequency changes

– Neighbor addition and deletion
– Formation of new location areas – Addition of new cellsites

Database Parameter Changes • Many problems can be solved by changing some database parameters.

•

Some of the common changes are
– – – – Handover parameters and thresholds Maximum transmit power of BTS Paging parameters SDCCH Parameters

Antenna Optimization • This includes changing of antenna tilts, orientations, positions. Sometimes the antenna may also be changed.

Frequency Changes • Frequency changes help us to control the interference in the network.

•
•

However one should be careful when doing these changes so that this changes do not affect the other sites adversely.
If there are a lot of changes it is advisable to change the whole frequency plan.

•

A careful study of cell coverage area and server area helps in making those changes.

Neighbor Addition And Deletion • • Many problems arise due to wrong neighbor definitions or missing neighbors. Neighbor definitions must be reviewed on a regular basis. Statistics and drive tests provide good inputs for this purpose.

Formation Of New Location Areas • Sometimes to solve paging load problems it might be required to for new location areas. Addition of new cell sites • Sometimes to solve coverage hole problems we need to add more site (normally micro or pico cells)

Path Balance • • • • • Many problems also may arise due to poor path balance. Hence it is important that we make a mention about it. Path balance data can be collected from the statistics. As we use different frequencies for uplink and downlink, we have different footprints for the uplink and the downlink . It is imperative that the footprints match. If the downlink is stronger it implies that the mobiles at the boundaries of the serving area are not able to reach the BTS and there is a uplink problem. Similarly if the uplink is stronger it implies a downlink problem.

•

THE RF PATH
PBS

Path Loss Downlink
MS Sensitivity • • • Noise Fading Interference PMS Path Loss Uplink

BS Sensitivity

TYPICAL QUATERLY REPORT FORMAT

Project Name
Quaterly Optimization Report Region xxx From 1st April to 30th June

Table Of Contents
executive summary 1. 2. Summary of activities completed in the last quarter Summary of activities planned for the next quarter 1 2 8

3.

Performance Data

13

executive summary
This Report contains a summary of all the major optimization activities carried out and recommendations made by yyy durring the period of 1st April – 30th June 2000 in the XXX Region. The report is structured as follows: 1. • • • • 2. • • • 3. • Summary of activities completed in the last quarter Site modification recommendations Site modifications completed New sites accepted Major activities completed (eg. new frequency plan, expansion Summary of activities planned for the next quarter Site surveys planned Pending site modifications to be completed Major planned activities (eg. new frequency plan, expansion plan, etc.) Performance Data Call Setup Success Rate and Drop Call Rate trends for BSC’s optimised during the last quarter. plan, etc.)

1.
1.1

Summary of activities in 2nd quarter 2000 Table of site modifications recommended

1.2
1.3 1.4

Table of Site modifications completed
Table of new sites accepted Description of major activities completed

2.
2.1 2.2 2.3

SUMMARY OF ACTION PLAN FOR 3RD QUARTER 2000 Table of site surveys planned Table of pending site modifications planned Description of major activities planned

3. NETWORK PERFORMANCE DATA Per-BSC trends of Call Setup Success Rate and Drop Call Rate for all optimised BSC’s

Tables to be inserted in Quaterly Reports
Table of recommended site modifications CELL ACTION S/N BSC NAME CELL ID REQUIRED
1 2 3 4 5 6 7

DATE SURVEYED

REMARKS

Table of completed site modifications CELL S/N BSC NAME CELL ID
1 2 3 4 5 6 7

ACTION REQUIRED

DATE COMPLETED

REMARKS

Tables to be inserted in Quaterly Reports
Table of new sites accepted S/N
1 2 3 4 5 6 7

BSC

CELL NAME

CELL ID

DATE ACCEPTED

REMARKS

Table of planned site surveys CELL S/N BSC NAME CELL ID
1 2 3 4 5 6 7

SURVEY DATE PLANNED

REMARKS

Tables to be inserted in Quaterly Reports
Table of planned site modifications CELL S/N BSC NAME CELL ID
1 2 3 4 5 6 7

ACTION REQUIRED

DATE PLANNED

REMARKS

Call Setup Success Rate(%)
10 20 30 40 50 60 70 80 90 100 0

15APR2000 17APR2000 19APR2000 21APR2000 23APR2000 26APR2000 02MAY2000 04MAY2000 06MAY2000 08MAY2000 10MAY2000 12MAY2000 16MAY2000 18MAY2000

Graphs to be inserted in Quaterly Reports

Optimization started Date
20MAY2000 22MAY2000 24MAY2000 30MAY2000 01JUN2000 05JUN2000 07JUN2000 09JUN2000 12JUN2000 14JUN2000 16JUN2000 18JUN2000 20JUN2000 22JUN2000

Call Setup Success Rate (%)

Drop Call Rate(%)
0.5 1.5 2.5 0 1 2

15APR2000 17APR2000 19APR2000 21APR2000 23APR2000 26APR2000 02MAY2000 04MAY2000 06MAY2000 08MAY2000 10MAY2000 12MAY2000 16MAY2000 18MAY2000 20MAY2000 22MAY2000 24MAY2000 30MAY2000 01JUN2000 05JUN2000 07JUN2000 09JUN2000 12JUN2000 14JUN2000 16JUN2000 18JUN2000 20JUN2000 22JUN2000

Graphs to be inserted in Quaterly Reports

Optimization Started Date

Drop Call Rate (%)

TCH RF Loss Rate(%)
0.2 1 2 0.4 0.6 0.8 1.2 1.4 1.6 1.8 0

15APR2000 17APR2000 19APR2000 21APR2000 23APR2000 26APR2000 02MAY2000 04MAY2000 06MAY2000 08MAY2000 10MAY2000 12MAY2000 16MAY2000 18MAY2000

Graphs to be inserted in Quaterly Reports

Optimization Started Date
20MAY2000 22MAY2000 24MAY2000 30MAY2000 01JUN2000 05JUN2000 07JUN2000 09JUN2000 12JUN2000 14JUN2000 16JUN2000 18JUN2000 20JUN2000 22JUN2000

TCH RF Loss Rate (%)

SDCCH RF Loss Rate(%)
0.5 1.5 2.5 0 1 2

15APR2000 17APR2000 19APR2000 21APR2000 23APR2000 26APR2000 02MAY2000 04MAY2000 06MAY2000 08MAY2000 10MAY2000 12MAY2000 16MAY2000 18MAY2000

Graphs to be inserted in Quaterly Reports

Optimization Started Date
20MAY2000 22MAY2000 24MAY2000 30MAY2000 01JUN2000 05JUN2000 07JUN2000 09JUN2000 12JUN2000 14JUN2000 16JUN2000 18JUN2000 20JUN2000 22JUN2000

SDCCH RF Loss Rate (%)

Typical Optimization Report

Typical Optimization Report

END


				
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Description: DISCRIPTION OF GSM NETWORKS