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GSM Network Planning Principles

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					OMF000502 Network Planning
    Principle ISSUE1.3




 Wireless Training Department
Course Contents


Introduction to GSM network


Mobile radio link


Network planning procedure


Advanced network planning
                Introduction to GSM Network


   1. GSM system architecture
   2. GSM bandwidth
   3. Difference between GSM900 and GSM1800
   4. GSM Logical channels
            GSM System Architecture




                        VLR        HLR
Other MSC                          EIR
                                   AuC
                                            OMC




                              Other BTS´s
                    GSM Bandwidth



GSM 900 :
                            890                     915     935    960

Channel spacing 200kHz                Duplex Spacing : 45 MHz




GSM 1800 :

Channel spacing 200kHz


             1710           1785             1805                 1880

                         Duplex Spacing : 95 MHz
       Difference Between GSM900 and GSM1800


   GSM900 and GSM1800 are similar


                           GSM 900           GSM 1800
     Frequency band        890...960 MHz    1710...1880 MHz
     Number of channels   124                374
     Channel spacing      200 kHz            200 kHz
     Access technique     TDMA               TDMA
     Mobile power          0.8 / 2 / 5 W     0.25 / 1 W

              There are no major differences between GSM 900
              and GSM 1800
                                          Logical Channels


   GSM900/GSM1800 logic channel architecture


                                    Logical Channels

                  Common Channels                            Dedicated Channels
                      (CCH)                                      (DCH)




      Broadcast Control       Common Control                              Traffic Channels
                                                  Control Channels
      Channel (BCCH)          Channel (CCCH)                                (TCH)



FCH    SCH      BCCH         PCH   AGCH    RACH   SDCCH      FACCH                TCH/F      TCH/H
                (Sys Info)

                                                           SACCH                  TCH/9.6F
                                                                                  TCH/ 4.8F, H
                                                                                  TCH/ 2.4F, H
            Downlink Channels


                   FCCH
                   SCH
Common      BCCH
                   BCCH
Channels    CCCH   PCH
                   AGCH




                   SDCCH
            DCCH   SACCH
Dedicated          FACCH
Channels    TCH
                   TCH/F
                   TCH/H
Uplink Channels




RACH       CCCH
                   Common
                   Channels




  SDCCH
            DCCH
  SACCH
  FACCH
                   Dedicated
   TCH/F
                   Channels
            TCH
   TCH/H
                  Use of Logical Channels


“off” state   Search for frequency correction burst
                                                      FCCH
              Search for synchronization sequence     SCH
              Read system information                 BCCH


idle mode     Listen paging message                   PCH
              Send access burst                       RACH
              Wait for signaling channel allocation   AGCH

dedicated     Call setup                              SDCCH
mode
              Assign traffic channel
                                                      SDCCH
              Conversation
                                                      TCH
              Call release
                                                      FACCH
 idle mode
                             Logical Channels Mapping


   Logical channels are mapped to physical channels
         Signaling : sequences of 51 frames
         Traffic :          sequences of 26 frames
    BCCH + CCCH (downlink)

    F SBBBBCCCCF SCCCCCCCCF SCCCCCCCCF SCCCCCCCCF SCCCCCCCC -


                                     51 TDMA frames ~ 235,4 msec
    BCCH + CCCH (uplink)

    RRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRR




         For combined BCCH
             CCCH blocks can be either PCH or AGCH
             Some blocks may be configured as SDCCH
   Exercises
        1. Write down the frequency used for uplink and downlink.
           Answer:      GSM system uses different frequency for uplink and
             downlink.

            GSM900:
                Uplink: 935---960                 Downlink: 890---915
            GSM1800:
                Uplink: 1805--1880                Downlink: 1710--1785
   Exercises
        2. Write down the types of logical channels and the hierarchy

         Answer:
                                          Logical Channels

                        Common Channels                            Dedicated Channels
                            (CCH)                                      (DCH)




            Broadcast Control       Common Control                              Traffic Channels
                                                        Control Channels
            Channel (BCCH)          Channel (CCCH)                                (TCH)



      FCH    SCH      BCCH         PCH   AGCH    RACH   SDCCH      FACCH                TCH/F      TCH/H
                      (Sys Info)

                                                                 SACCH                  TCH/9.6F
                                                                                        TCH/ 4.8F, H
                                                                                        TCH/ 2.4F, H
Course Contents


Introduction to GSM network


Mobile radio link


Network planning procedure


Advanced network planning
                         Mobile Radio Link


   1. Radio wave propagation
   2. Propagation models
   3. Antenna systems
   4. Diversity technique
   5. Interference and interference reduction
   6. Link budget
                        Radio Link Propagation

   Multi-path propagation
        Radio path is a complicated propagation medium

   Limited transmitting energy
        The service range is determined by the transmission power of
         mobiles
        Battery life-time

   Limited spectrum
        Set upper limitation for data rate (Shannon´s theorem)
        Additional effort needed for channel coding
        Frequency reused result in self- interference
                 Radio Propagation Environment


   Multi-path propagation
   Shadowing
   Terrain
   Building
   Reflection
   Interference
                                             Reflections


   Strong echoes can cause excessive transmission delay
        No impact If the delay falls in the equalizer window
        Cause self-interference if the delay falls out of the equalizer
         window
                 direct signal
                 strong reflected signal




     amplitude                                    long echoes, out of equalizer window:
                                                  self-interference




                                                                      delay time
                    equalizer window 16 s
                                     Fading(1)


   Slow fading (Lognormal Fading)
        Shadowing due to large obstacles
         on propagation direction


                                                Level (dB)
   Fast fading (Rayleigh fading)               +10
        Serious interference from multi-path
                                                0
         signals
                                                -10


                                                -20
                                                                         920 MHz
                                                                         v = 20 km/h
                                                -30
                                                      0      1   2   3   4             5m
                          Fading(2)


          power
                                    Rayleigh
                                    fading
+20 dB
                                                   lognormal
                                                   fading


  mean
  value




- 20 dB




                  2 sec     4 sec       6 sec   time
                              Signal Variations

              Rayleigh            Lognormal       Large scale
              fading              fading          variation
Cause         Superposition of    Shadowing or    Prop. path profile, terrain
              multiple            reflection by   & clutter structure, Earth
              propagation         cars, trees,    curvature
              paths with          buildings
              different phase

Correlation   <                  10 ... 100m     > 100m


Prediction    unpredictable       mostly          predictable (maps, terrain
                                  predictable     database)
                                  (buildings!!)

Planning      apply statistical   consider        use maps or digital
              thresholds for      lognormal       terrain & clutter
method        Rayleigh fading     distribution    databases to predict
              signals             around local    (50 ..200m pixel
                                  mean (use  =   resolution)
                                  3 ... 10dB)
                                    Propagation


   Free- space propagation
                                                              D
    Signal strength decreases with distance increases

   Reflection
        Specula R.
           Amplitude    : A -->   α*A (α< 1)
           Phase       : --> -Ф                                  specula reflection

           Polarization : material determining phase shift

        Diffuse R.
           Amplitude : A -->      α*A (α<< 1)
           Phase       : random
           Polarization : random
                                                                    diffuse reflection
                                Propagation


   Absorption
        Heavy amplitude attenuation        A   A - 5..30 dB

        Material determining phase shift

   Diffraction
        Wedge-model
        Knife edge
        Multiple knife edges
                         Mobile Radio Link


   1. Radio wave propagation
   2. Propagation models
   3. Antenna systems
   4. Diversity technique
   5. Interference and interference reduction
   6. Link budget
                           Propagation Model


   Historical CCIR- Model for Radio station
        Not very accurate nor serious

   Okumura- Hata
        Empirical model
        Measure and estimate additional attenuations
        Applied for larger distance estimation (range: 5 .. 20km)
        Not suitable for small distance ( < 1km)
                                   Hata Model


   Model used for 900 MHz

       L  A  B log f  1382 log hb  a (hm )
                               .
        (44.9  6.55 log hb ) log d  Lmorpho
    with
    f      frequency in MHz                   additional attenuation due
    h      BS antenna height [m]              to land usage classes
    a(h)   function of MS antenna height
    d      distance between BS and MS [km] and

    A= 69.55, B = 26.16 (for 150 .. 1000 MHz)
    A= 46.3 , B = 33.9 (for 1000 ..2000MHz)
                         Land Usage Types


   Urban            small cells, 40..50 dB/Dec attenuation
   Forest            heavy absorption; 30..40 dB/Dec; differs with
                      season (foliage loss)
   Open, farmland   easy, smooth propagation conditions
   Water             propagates very easily ==> dangerous !
   Mountain surface strong reflection, long echoes
   Glaciers          very strong reflection; extreme delay , strong
                      interferences over long distance
   Hilltops          can be used as barriers between cells, do not
                      use as antenna or site location
                      Walfish- Ikegami Model


   Model used for urban micro-cell propagation. Assume regular
    city layout (“Manhattan grid”). Total path loss consists of three
    parts:
        Line-of-sight loss LLOS
        Roof-to-street loss LRTS
        Mobile environment loss LMS

                             d



                         h
                                       w
                                       b
                             Mobil Radio Link


   1. Radio wave propagation
   2. Propagation model
   3. Antenna system
   4. Diversity technique
   5. Interference and interference reduction
   6. Link budget
                       Antenna Characteristics


   Lobes
        Main lobes
        Side and Back lobes
        Front-to-Back ratio

   Half-power beam-width
   Antenna downtilt
   Polarization
   Frequency range
   Antenna impedance
   Mechanical size
                    Coupling Between Antennas

                                                      main lobe

   Horizontal separation
        Sufficient decoupling distance: 5-10λ
        Antenna patterns superimposed if
         distance too close
                                                      5 .. 10
   Vertical separation
        Decoupling distance:1λ can provide good RX /TX decoupling

   Minimum coupling loss
                          Installation Examples


   Recommended decoupling
        TX - TX: ~20dB
                                                                 0,2m
        TX - RX: ~40dB

   Horizontal decoupling distance depends on
        Antenna gain
                                   Omni-directional.: 5 .. 20m
                                   directional : 1 ... 3m
        Horizontal rad. pattern

   Omni-directional antenna
        Use vertical separation for RX and TX
        Use vertical separation (“fork”) for RX and diversity RX

                                     Vertical decoupling is much more effective
                        Installation Examples


   Directional antenna
   Antenna downtilt
        Improve hotspot coverage
        Reduce interference




                                       5..8 deg
                                     Feeder


   Feeder parameter
         Type           Diameter       1800MHz       900MHz
                                   (mm)          dB/100m
         dB/100m


         3/8”           10              14             10

         5/8”           17               9              6

         7/8”           25               6              4

         1 5/8”         47               3              2




                   Use the short feeder whenever possible
                          Distributed Antennas


   Leaking feeder
        Cables with very high loss per length unit “distributed antenna”
         often used for tunnel coverage. This kind of feeder is expensive



                                      Propagation loss: 4 ... 40 dB/100m



                                                                           50 Ohm
                                coupling loss: ~ 60 dB (at 1m dist.)


   Optic fiber distribution system
        Distribute RF signal radiate from discrete antenna points at
         remote locations via (very thin) optic fiber.
                                Repeaters


   Repeater type
        Narrow-band Repeater
        Wide-band Repeater

   The Repeater is used to relay signal into shadowed area
        Behind hill
        Into valley
        Into building
                                              decoupling ~40 dB needed

Note: The Repeater needs a host cell
                         Mobile Radio Link


   1. Radio wave propagation
   2. Propagation models
   3. Antenna systems
   4. Diversity technique
   5. Interference and interference reduction
   6. Link budget
                                Diversity


   Time diversity
                                       t
      Coding, interleaving

   Frequency diversity
                                           f
      Frequency hopping
   Space diversity
      Multiple antennas
   Polarization diversity
      Dual-polarized antennas

   Multi-path diversity
      Equalizer
                         Benefit From Diversity


   Diversity gain depends on environment
        Antenna diversity
           3dB gain
           More path loss acceptable in link budget
           Higher coverage range



                  R(div) ~ 1,3 R   A    1.7 A
                                   70% more coverage per cell
                                   Needs, less cells in total
             R
                             The above case can be satisfied
                             only under ideal condition. That
                             is the environment is infinitely
                             large and flat
                         Mobile Radio Link


   1. Radio wave propagation
   2. Propagation models
   3. Antenna systems
   4. Diversity technique
   5. Interference and interference reduction
   6. Link budget
                          Interference


Signal quality =
    sum of all expected signals               carrier (C )
    sum of all unexpected signal   =        interference (I)
                        atmospheric
expected signal         noise


                            other signals




Notes: GSM specification : C / I >= 9 dB (Co-Channel)
                            Effects of Interference


   Affect signal quality
   Cause bit error
         Repairable errors : channel coding, error correction
         Irreducible errors : phase distortions

   Interference situation is
         Non- reciprocal    :   uplink <> downlink
         Unsymmetrical     :    different situation at MS and BTS

   C/I
         Co-Channel C/I          : 9dB
         Adjacent Channel C/I : -12dB
                    Signal Quality in GSM


    RX Quality
    RXQUAL class : 0 ... 7



                RXQUAL   Mean BER   BER range
                class       (%)     from... to
                0        0.14       < 0.2%
       good     1        0.28       0.2 ... 0.4 %
usable signal   2        0.57       0.4 ... 0.8 %
                3        1.13       0.8 ... 1.6 %
  acceptable    4        2.26       1.6 ... 3.2 %
                5        4.53       3.2 ... 6.4 %
   unusable     6        9.05       6.4 ... 12.8 %
   signal       7        18.1       > 12.8 %
                        Interference sources


   Multi-path (long echoes)
   Frequency reuse
   External interference

      Note : Interference has the same effect as poor coverage.



                  Reduce the interference
                  as possible.
              Methods for reducing Interference


   Frequency planning
   Suitable site location
   Antenna azimuth, downtilt and height


                                              bad location




                              good location
               Methods for reducing Interference


   Frequency hopping
      A diversity technique, frequency diversity include:
         Less fading loss
         De-coding gain
         Interference averaging

   Power control based on quality
        Evaluate signal level and quality

   DTX
        Silent transmission in speech pauses
                Methods for reducing Interference


   Adaptive antenna
        According to subscriber distribution, concentrate signal energy
         to certain direction.

   Adaptive channel allocation
        Always assign the best available channel during call setup.
                          Frequency Hopping


   Diversity technique
        Frequency diversity can reduce fast fading effects
        Useful for static or slow-moving mobiles

   Cyclic base-band hopping
        TRX hops cyclic between its allocated frequencies

   RF hopping
        Either cyclic or random hopping
        Needs wideband combiner
        Can use any frequency included in the MA
                               Power Control


   Save battery life-time
   Minimize interference

     GSM : 15 steps and 2 dB for each

     Use power control in both uplink and downlink
     triggered by level or quality
                                  signal
                                  level              target level
                                                     e.g. -85 dm



         Power control isn‟t allowed
         on BCCH

                                                              time
                                          DTX


   DTX (Discontinuous transmission)
        Switch transmitter off in speech pauses and silence periods,
         both   sides   transmit   only   silence   updates   (SID frames)
         comfort noise generated by transcoder.

   VAD: voice activity detection
   Transcoder is informed the use of DTX/ VAD




           Battery saving and
           interference reducing
                         Mobile Radio Link


   1. Radio wave propagation
   2. Propagation models
   3. Antenna systems
   4. Diversity technique
   5. Interference and interference reduction
   6. Link budget
                       Link Budget Calculation


   Why we need a link budget?
   Which will decide the coverage range?
   The coverage range is limited by the weaker one.
   Two-way communication needed
        link usually limited by mobile transmitting power

   Desired result: downlink = uplink

                Link budget should
                be balanced
   Exercises
        1. Write down the diversity techniques.
        2. Write down the antenna‟s main parameters.
        3. Write down the method used to reduce interference.
   Answer
        1.The diversity techniques are time diversity, frequency diversity,
         space diversity and polarization diversity.
        2.The antenna‟s main parameters are lobes (main lobes,
         side/back   lobes),   front-to-back   ratio,   half-power   beam-
         width ,antenna downtilt, polarization, frequency range, antenna
         impedance, mechanical size etc..
        3.The methods used to reduce interference are frequency
         hopping, DTX, power control based on qulality, adaptive
         antenna, optimized channel allocation.
Course Contents


Introduction to GSM network


Mobile radio link


Network planning procedure


Advanced network planning
                  Network Planning Procedure


   1. Cellular planning principle
   2. Network topology
   3. Traffic estimation
   4. Coverage planning
   5. Frequency planning
   6. Site selection
   7. Transmission planning
                  Network Planning Principle


                            initial           marketing
                            dimensioning



                                           business
                                           plan
transmission   coverage
 plan          plan


                                   traffic                 parameter
                                   estimate                plan


                Frequency
                plan

                                                final
                                                topology
                      Scope of Network Planning

   Operator‟s requirements                                      External information
        Subscriber forecasts                                           Terrain data

        Coverage requirements Network planning                         Population data

        Quality of service      Data acquisition
                                 Site survey
                                                                        Bandwidth available
                                      Field measurement evaluation

        Recommended sites            CW design and analysis
                                      Transmission plan




   Network design                                               Network performance
        Number & configuration of BSC                                  Gos

        Antenna specifications                                         Margin calculations

        BSS topology                                                   Interference probabilities

        Frequency plan                                                 Quality observation

        Network evolution strategy
                                Input Data


   Maps
        Main city
        Important road
        Location of mountain range
        Inhabited area
        Shore line

   Local knowledge
        Typical architecture
        Structure of city
                            Demographic Data


   Statistical yearbook
        Largest town and city
        Population distribution
        Where are the expected subscribers
                                                     250 000 pop.
   Local knowledge
        Population migration route
                                              400 000 pop.

        Traffic volume
        Subscriber concentration area
                                                    300 000 pop.
                    Network Configuration


Estimate number of BTS needed
  VERY rough initial estimation :
   total operator‟s bandwidth
                                  = average number of TRX allowed per cell
   planned freq. reuse rate

            number of BTS needed for traffic reasons

Evaluate achievable cell coverage range
    =f (topography, requirements, signal levels,
    environment, ...)
             number of BTS needed for coverage reasons
                                                    Finances         Marketing




                                                                Planning
                            Network Planning


   1. Cellular planning principle
   2. Network topology
   3. Traffic estimation
   4. Coverage planning
   5. Frequency planning
   6. Site selection
   7. Transmission planning
                Network Topology




Umbrella cell
Macro cell
Micro cell
Pico cell
                            Macro Cell Network


   Cost performance solution
   Suitable for covering large area
        Large cell range
        High antenna position

   Cell ranges 2 ..20km
   Used with low traffic volume
        Typically rural area
        Road coverage

   Normally Use omnidirectional antenna
     Exception: Use beamed antenna for road coverage
                          Micro Cell Network


   Capacity oriented network
   Suitable for high traffic area
   Mostly used with beamed cell               0,5 .. 2km

        Cost performance solution
        Usage of available site‟s equipment

   Typical application
        Medium town
        Suburb

   Typical coverage range: 0.5 .. 2km
                              Cell coverage range


   Achievable cell coverage depend on
        Frequency band (450, 900, 1800 MHz)
        Surroundings and environment
        Link budget figure
        Antenna type
        Antenna direction
        Minimum required signal level
                        Hexagons and Cells


   Three cells ( three hexagons)
                  Network Planning Procedure


   1. Cellular planning principle
   2. Network topology
   3. Traffic estimation
   4. Coverage planning
   5. Frequency planning
   6. Site selection
   7. Transmission planning
                            Traffic Estimation


   Estimate number of subscribers
        Long-term prediction
        Forecast Subscribers

   Expected traffic load per subscriber
   Particular habits of subscribers
   Busy hour conditions
        Busy hour of the day
        Traffic patterns
                              Traffic Planning


   Estimation of expected traffic
        Number of subscribers in area
        Traffic load per subscriber
        Coverage
     ==> traffic per sq.km
               ==> traffic per cell
                    ==> number of TRX needed per BTS
        Allow extra capacity for roamer and busy hour traffic


               Transmission should not be the
               bottleneck of the system
                                          Traffic Patterns


Traffic   varies between different hours, estimated traffic must be
able to satisfy the peak loads. Busy hour traffic is typically twice
that of the average.


            100 %
             90           peak hour
             80           off-peak

             70
             60
             50
             40
             30
             20
             10
              0
                  0   2      4    6   8    10   12   14   16   18   20   22   24 hr
                  Network Planning Procedure


   1. Cellular planning principle
   2. Network topology
   3. Traffic estimation
   4. Coverage planning
   5. Frequency planning
   6. Site selection
   7. Transmission planning
                                     Coverage Planning

external inputs:
(traffic, subs. forecast,
coverage requirements...)
                                               nominal cell plan
                                                                        suggestions for
             Initial network dimensioning                                site locations
               TRXs, cells, sites                                        cell parameters
               bandwidth needed                                          coverage achieved
               NW topology



                                                                      coverage prediction
                                                                       signal strength
                                                                       multi-path propagation




                      create cell
    go to
                      data for                                               coverage,
 frequency                                                                                    N
                      BSC                                                       ok?
  planning

                                                                            Y
                                                                           site acquisition
                                                     real cell plan
                              field measurements

       planning                                                        Y                      N
                                                                            site accepted ?
       criteria fulfilled?
                        N
                        Coverage Requirements


   Rollout phases and time schedules
   Coverage requirement
        Agree on min. level for outdoor coverage                  phase 1
                                                                   CW launch
   Loss requirement
   Indoor coverage area
   Mobile classes
   Operator‟s cell deployment strategies
                                                    rollout
        Omni-cell site in rural area                         rollout
                                                    phase 3
                                                              phase 2
        Directional site in urban area
                           Coverage Planning


   Loss
        Due to coverage
        Due to interference




            Full coverage of an area can hardly be
            guaranteed ! common values: 90~95%
                            Network planning


   1. Cellular planning principle
   2. Network topology
   3. Traffic estimation
   4. Coverage planning
   5. Frequency planning
   6. Site selection
   7. Transmission planning
                          Frequency Planning


   Why we reuse the frequency?
      8 MHz = 40 channels * 8 timeslots = 320 users
       ==> max. 320 simultaneous calls!!!
   Limited bandwidth
   Interference are unavoidable
        Minimize total interference in network

   Use calculated propagation prediction for frequency allocation
                          Frequency Planning


   Target
     Find solution to minimize interferences in the network

   Traditional method
        Hexagonal cell patterns
        Regular grid
        Cluster sizes

                                                    D
      Frequency reuse distance:
      D = R *sqrt(3*cluster-size)           R
                            Frequency Planning


   Frequency planning always consider the following case
        Actual situation is different.
        Power control, actual traffic and distribution of subscribers.

   Average frequency reuse rate is a criteria for good allocation
    scheme:


                      physical practical
                      limit    limit
           0                10             20
                                                  safe, but
                                                uneconomical
                             Frequency Reuse


   Reuse frequency as often as possible
        Increase network capacity
        But maybe cause some interference                                      f2         f6
                                                                                                                    f3
                                                                                     f3
                                                                                               f5
   Consideration for frequency reuse                       f5
                                                                           f4
                                                                                      f7
                                                                                                          f4
                                                                                                                     f7            f2
                                                       f7                                           f2         f6
                                                                 f2             f6                                                  f3
        Interference matrix calculation                                                  R              f3
                                                                                                                f5
                                                                      f3                                                      f4
                                                                                 f5
                                                  f5                                           f4         D
        Propagation model tuning                           f4
                                                                       f7             f2
                                                                                                                     f2
                                                                                                    f6
                                                                 f6                                                      f3
        Minimize total interference in network                                           f3         f5
                                                                                                                f4
                                                                  f5
                                                                                 f4
                                       Multiple Reuse Rate


   Frequency reuse rate
        measurement criteria for effectiveness of frequency plan
         Co-relationship : effectiveness                                    interferences
        Interaction with coverage planning
        Multiple reuse rate increase effectiveness of freq. plan




                        1      3           6       9       12          15       18      21


    same frequency          tight reuse planning                        safe planning
    in every cell               (tight layer)                           (BCCH layer)
    (spread spectrum)                              normal planning
                                                   (TCH macro layer)
                      Multiple reuse rate

Capacity increase with multiple reuse rate
   e.g. network with 300 cells                                BWi
   bandwidth : 8 MHz (40 radio channels)        cap. N    re  use
                                                                    i

Single reuse (4X3)
   Network capacity = 40/12 * 300 = 1000 TRX

Multiple reuse:
   BCCH layer:      reuse =14,     (14 freq.)
   normal TCH:      reuse =10,     (20 freq.)
   tight TCH layer: reuse = 6,     (6 freq.)
      ==> Network capacity = (1 +2 +1)* 300 = 1200 TRX
                  Network Planning Procedure


   1. Cellular planning principle
   2. Network topology
   3. Traffic estimation
   4. Coverage planning
   5. Frequency planning
   6. Site selection
   7. Transmission planning
                              Site Location


   Cell performance has a close relationship with site location
   Site is long-term investment
   Site acquisition is a slow process
   Hundreds of sites needed per network




                 Site is a valuable long-term
                 asset for the operator
                                       Bad Site Location


   Avoid hill-top location for site
        Uncontrollable interference
        Cross coverage
        Bad handover behavior



                         wanted cell               uncontrolled, strong
                         boundary                  interferences




         cross coverage areas:
                             Good Site Location


   Prefer site off the hill-top
        Use hill to separate cell
        Contiguous coverage area
        Need only low antenna height if site are slightly elevated above
         valley bottom

                         wanted cell
                         boundary
                           Site Selection Criteria


   Radio criteria                           Non-radio criteria
        Good view in main beam                   Space for equipment
         direction                                Availability of leased transmission
        No obstacles                              line or microwave link

        Good visibility of terrain               Power supply

        Antenna installation situation           Access restrictions

        LOS to next microwave site               House owner

        Short feeder length                      Rental costs
                   Site Acquisition Process



                              Site select
                                                       site owner
      radio planner




measurement                                 network
teams                                       operator




              fixed network
              planner                 architect
                              Site Information


   Questionnaire
        Collect all necessary information about site
        Site coordinates, height above sea level, exact address
        House owner
        Type of building
        Building materials
        Possible antenna heights
        360deg photo (clearance view)
        Neighborhood, surrounding environment
        Drawing sketch of rooftop
        Antenna installation conditions
        Access possibilities (road, roof)
        BTS location, approximately feeder lengths
                  Network Planning Procedure


   1. Cellular planning principle
   2. Network topology
   3. Traffic estimation
   4. Coverage planning
   5. Frequency planning
   6. Site selection
   7. Transmission planning
                         Transmission Planning


   A great portion of yearly network operational cost is
    transmission maintenance cost.
   Transmission planning is for minimizing the overall cost


     Radio part design                 Fixed part design

     BTS                              BTS
                        BSS                       MSC   BSS
                                                           BSC Hub


                              BTS                             BTS



    BTS                              BTS
                  BTS                               BTS
        Transmission Concept


        Transmission methods
CATV           ISDN                 ATM
        PCM              HDSL

        Transmission techniques
              PDH          SDH


         Transmission media

Fiber               Copper cable

   Coaxial cable                   Microwave radio
                                     Terrestrial/satellite
                           Microwave Links

   High capacity transmission links, frequency range: 7~38 GHz


   Normal transmission link                      Pro
        Needs extra frequencies                        Low operating costs
        Link quality depend on weather                 Easy to install
        Not always available at ideal sites            Flexible
         (LOS path)                                     Quick & reliable solution
        Long distance hops are problematic




                                 Repeater
                                 station
      Terminal                                              Terminal
      station A                                             station B
                Basic Transmission Topologies


   POINT-TO-POINT                      STAR (Concentration points)




   MULTIDROP CHAIN                     LOOP




    The basic criteria for choosing transmission
topologies is Costs vs. Fail Safety (redundancy).
                                 Network topology


   Prefer centralized or decentralized network architecture

        BTS
                MSC



                           BTS
               BSC

       BTS
                     BTS




       BTS
               BSC/ MSC

                                     2 small BSC plus
                                     cheap transmission
                           BTS
                                                          1 large BSC plus
                                                          expensive
                                                          transmission
      BTS
                 BTS
Course Contents


Introduction to GSM network


Mobile radio link


Network planning procedure


Advanced network planning
                    Advanced Network Planning


   1. Network evolution
   2. Indoor coverage
   3. Tunnel coverage
   4. Parameters
                         Cell Evolution




Umbrella Cell   Macro Cell     Micro Cell     Pico Cell
5-50Km          1-5Km          100m-1Km       10m-100m
Early 80‟s      Mid-end 80‟s   Mid 90‟s       Mid-end 90‟s

       Macro Cell                   Layered Network
                                  Layered Network



                        High layer station




                   Middle layer station                           Middle layer station


                                  Low layer station    Low layer station Low layer station
      Low layer station
                                                 Indoor station
                                                                       Indoors station
Indoors station Indoors station
                     Network Capacity evolution


   Measure for network spectrum efficiency
                                                     Directed
        Erl/ (MHz * sq.km)                           Retry


   A function of                                                    Load HO
                                                  Power
                                                  Control
        Bandwidth
                                                                   Half-rate
        Frequency efficiency of technology                         code
                                                   DTX

        Frequency reuse
                                                                  multiple cell
        Cell size                                                 coverage
                                                 Load
                                              distribution


                                                                Frq. hopping
                    Advanced Network Planning


   1. Network evolution
   2. Indoor coverage
   3. Tunnel coverage
   4. Parameters
                             Why Indoors


   Indoor coverage become the main competition between operators
   Subscribers expect continuous coverage and better quality
   Outdoor cell can‟t provide sufficient indoor coverage
                                                 Good
                                                Quality!




                                                    INDOOR SOLUTION
                             Benefits


                    Continuous Coverage

                    Low Transmission Powers (BTS/MS)

  Dedicated
Indoor Solution    Subscriber expectation   Office Equipment
                  Continuous Service        Less Interference

                  Good Quality

                  Safety

                  MS Battery Life-time
                              Building Penetration Loss


   Signal level in building is estimated by using a building
    penetration loss margin
   Big differences between rooms with window and without
    window(10~15 dB)
                                              signal level increases with floor
                                              number :~1.5 dB/floor (for 1st
                                              ..10th floor)




                  Pindoor = -3 ...-15 dB

    Pref = 0 dB                            Pindoor = -7 ...-18 dB

                                                                                      rear side :
                                                                                      -18 ...-30 dB


                   -15 ...-25 dB                                        no coverage
                            Building Penetration Loss


   Signal loss for penetration varies between different building
    materials, e.g.:
                                             mean value
     reinforced concrete wall, windows           17 dB
     concrete wall, no windows                   30 dB
     concrete wall within building               10 dB
     brick wall                                  9 dB
     armed glass                                 8 dB
     wood or plaster wall                        6 dB
     window glass                                2 dB


Total building loss = median values +
                            superimpose standard deviations +
                            (lognormal) margin for higher probabilities
                                 In-Building Path Loss


   Simple path loss model for in-building environment
        Outdoor loss: Okumura„s formula
                                                                            Lout
         Lout = 42,6 + 20 log( f ) + 26 .. 35 log( d )
        Wall loss
         Lwall = f (material; angle)                                     Lwall

        Indoor loss: linear model
         For Pico-Cells                                            Lin

         Lin = L0 +          d                                 d

      building type       loss       application example
      old house           0,7 dB/m   (urban l)
      commercial type     0,5 dB/m   (modern offices)
      open room, atrium   0,2 dB/m   (museum, train station)
                    Indoor Coverage Solutions


   Small BTS                     Antennas
        Mini BTS                      Distribute antenna
                                       Leaky cable

   Repeater                      Signal distribution
        Active                        Power splitter
        Passive                       Optical fiber
        Optical
                         Indoor Planning

  Single cell approach                  Multi-Cell approach


                                               t




            f1..f6                        f5       f3         f1
            f1..f6                        f6       f4         f2
            f1..f6                        f5       f3         f1



Example1:                            Example2:
1.2 MHz allocation                   1.2 MHz allocation
50 mErl/subscriber, GOS=2%           50 mErl/subscriber , GOS=2%
no frequency reuse:                  reuse per two floor, separate
                                     frequencies within one floor:
a) three floors                      a) three floors
      34.68 Erl=> 694 subscribers          52.12 Erl => 842subs
b) ten floors                        b) ten floors
      34.68 Erl => 694 subscribers         140 Erl => 2808 subs
                             Leaky cable


   Coaxial cable with perforated leads
   Radiating loss 10~40 dB per 100m
   Coupling loss typically 55 dB (at 1m)
   Produce constant field-strength along cable runs
   Work at wide-band
   Radiating loss become higher with high frequency
   Very large bending radius
   Formerly often used for tunnel coverage
   Expensive
                         Indoor Coverage Examples


   With Repeater
        Relay outdoor signal into target building
        Need donor cell, add coverage but not capacity

   With indoor BTS and distributed antenna
        Heavy loss bring by power splitting and cable
                                                                           Outdoor Antenna
                                 50m                             -50 dBm   Gain: 18 dBi

                           1:1
                                       4th floor
                                 50m
                                                      7/8'' Cable
                 1:1             50m
                                                      Loss: 4dB / 50m        4th Floor
                           1:1         3rd floor      Cable length : 25m
                                 50m
                                                                              3rd Floor
         1:1                     50m

                           1:1         2nd floor                              2nd Floor
                                 50m
                                 50m                                          1st Floor
                                       1st floor
                 1:1:1     1:1
                                 50m                                       Ground Floor
                                 50m
                                                                             Indoor Antenna
                           1:1         ground floor                           Gain: 9dBi
                                 50m

                                                                 Target Indoor Coverage Building
                                     Repeater


   Types of Repeater
        According to operating frequency
                                                                needs
           Wide-band Repeater                                  decoupling > amplification


           Narrow-band Repeater

        According to working method
           Passive Repeater
               Needs strong external signal, useful only with
            very short cables and seldom used
           Active Repeater
               Amplify and re-transmits all received signals
                                   Repeater


   Application examples
        Coverage for low traffic area
        Remote valley
        Tunnel
        Underground coverage
    The Bulb Principles




   ... is better than ...




Several smaller sites provide
more indoor coverage area
than a single large site
                     Newspaper Principles


   The newspaper-principle



          Indoor    coverage  may     be
          expected in locations where
          there is no enough daylight to
          read a newspaper comfortably
                    Advanced Network Planning


   1. Network evolution
   2. Indoor coverage
   3. Tunnel coverage
   4. Parameters
                 Wave Propagation in Tunnels


   Ideal antenna position: center of cross-section
   Distance to walls: min. 2λ
   Tunnel cross-section shape unimportant, if λ > 10
   Time dispersion decreases with distance
   Install antenna 50~100m before tunnel entrance
   Good signal coupling between successive tunnels



            Tunnels are very suitable environment
            for radio wave propagation
                         Tunnel Cross-Section


   Filling factor determines propagation condition
   Typical range for filling factors
        Road tunnels: 10%
        Metro: 60~90%


                                        filling factor =----------
                    Advanced Network Planning


   1. Network evolution
   2. Indoor coverage
   3. Tunnel coverage
   4. Parameters
                              BSS Parameters


   BSS Relevant Parameter for Network Planning
        Frequency allocation plan
        Logical radio configuration
        Transmitting power
        Definition of neighboring cells
        Definition of location areas
        Handover parameters
        Power control parameters
        Cell selection parameters
        Radio link time-out counter
        Topology of BSC- BTS network
                                Handover Types


   Intra-cell                  same cell but different carrier or timeslot
   Inter-cell                  different cells (normal case)
   Inter-BSC                   different BSC
   Inter-MSC                   different MSC
   Inter-PLMN                  (technically feasible, not supported)




      Intra-cell
                   Inte-rcell



                                                  inter-BSC
                           Handover Criteria


   1. Interference, UL and DL       9. MS Speed

   2. Bad C/I ratio                 10. Power Budget

   3. Uplink Quality                11. Good C/I ratio

   4. Downlink Quality              12. PC: Lower quality/level

   5. Uplink Level                   thresholds (DL/UL)

   6. Downlink Level                13. PC: Upper quality/level
                                      thresholds (DL/UL)
   7. Distance
   8. Rapid Signal Drop
                         Location Area Design


   Location update affects all mobiles in network
        Location update in idle mode
        Location update after call completion

   Location update brings extra burden to the network
   Good location area design should avoid ping-pong
    location update
                                             major road              Location area 2




                                                          Location area 1
            Paging VS Location update Traffic

signaling
traffic



                                                                function of user density,
                      function of                               cell size, call arrival rate ...
                      user mobility




             Paging
                                              Location update


                      optimum number                            # of cells in Loc. area
                      of cells in Loc. area



             minimize signaling traffic
             optimum varies with network evolution
   Exercises
        1. Write down the network evolution process.
        2. Write down solution and equipment for indoor coverage.
        3. Write down the types of handover.
   Answer
        1.The network evolution process is: Umbrella cell-> Macro cell -
         >Micro cell->Picro cell
        2. The solution and equipment for indoor coverage are:
         Mini BTS, Repeater, antennas( distribute antenna, leaky
         cable), signal distribution( power splitter, optical fiber).
        3.The handover types are: Inter BSC, Intra BSC, Intra cell, Inter
         cell, Inter MSC and Intra MSC.

				
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