Docstoc

QoS measurement of Zigbee home automation network using

Document Sample
QoS measurement of Zigbee home automation network using Powered By Docstoc
					                  Gurjit Kaur et al. / International Journal of Engineering Science and Technology (IJEST)



            QoS measurement of Zigbee home
            automation network using various
                  modulation schemes
                                                   Gurjit Kaur
                                               Faculty ECE Deptt.
                                            Rayat Polytechnic College
                                            Distt. SBS Nagar, Punjab
                                              guri_23s@yahoo.co.in
                                                  Kiran Ahuja
                                               Faculty ECE Deptt
                                                     DAVIET
                                             Distt. Jalandhar, Punjab
                                           askahuja2002@gmail.com

ABSTRACT
Increased demands on implementation of wireless sensor networks in automation praxis resulted in relatively
new wireless standard – Zigbee. The IEEE 802.15.4 standard specifies the multiple PHYs for 868, 915 and 2400
MHz three frequency bands. In this paper we presents the performance analysis of different modulation schemes
at different frequency range like ASK, BPSK and QPSK at 868, 915 & 2400 MHz based on their effect on the
quality of service parameter by using CBR application in Zigbee home automation network using static IEEE
802.15.4. The QoS parameters such as average end-to-end delay, jitter, and throughput are investigated as the
performance metrics. The results show that even though ASK at 868 MHz gives the highest throughput of 100%
which is highest amongst all five modulation schemes but still overall ASK at 915 MHz is the best suited
modulation schemes for CBR application of Zigbee home automation since it produced lowest jitter value of
0.03s and lowest average end-to-end delay value of 3.30s which are both favorable conditions for better
performance of CBR application of Zigbee home automation network.
Keywords
ASK, QPSK, BPSK, HOME AUTOMATION, CBR.
1. INTRODUCTION
The rapid progress of wireless communication and embedded micro-sensing MEMS technologies has made
wireless sensor networks (WSNs) possible. A WSN consists of many inexpensive wireless sensors capable of
collecting, storing, processing environmental information, and communicating with neighbouring nodes.
Applications of WSNs include wildlife monitoring, object tracking, and dynamic path finding [1,2].

Recently, many WSN platforms have been developed, such as MICA and Dust Network. For interoperability
among different systems, standards such as Zigbee/IEEE 802.15.4 [ 3] protocols have been developed.
Zigbee/IEEE 802.15.4 specifies a global standard on physical, MAC, and network layers for WSNs requiring
high reliability, low cost, low power, scalability, and low data rate. To meet these challenges, IEEE 802.15.4 [4]
low rate wireless personal area network (LR-WPAN) standard has been introduced. The goal of the IEEE
802.15.4 standard is to provide a highly reliable protocol for wireless connectivity among inexpensive, fixed and
portable devices [5]. These devices can form a sensor network or a Wireless Personal Area Network (WPAN).
Thus it suits wireless sensor network applications where a large number of tiny smart sensors having the low
power, low range, and low bandwidth are deployed in an ad hoc manner for the purpose of automation.

Zigbee is a relatively new technology for short-range wireless networking, which has low-power consumption,
low latency, and low cost. It is able to provide a transfer rate of up to 256 Kbps at 2.4 GHz within 10 m. It has a
maximum power consumption of 30mW when transmitting short-range data which allows a single battery to
power one Zigbee device from months up to years.




ISSN : 0975-5462                             Vol. 3 No. 2 Feb 2011                                           1589
                  Gurjit Kaur et al. / International Journal of Engineering Science and Technology (IJEST)


This paper provides the performance analysis of different modulation schemes like ASK, BPSK and QPSK at
868, 915 and 2400 MHz by measuring quality of service parameters such as average end-to-end delay, jitter and
throughput on the Zigbee home automation using static IEEE 802.15.4 star topology.

The rest of the paper is organized as follows. Section 2 discusses related works for performance evaluation of
IEEE 802.15.4 topology in various simulation environments. The overview of Zigbee and IEEE 802.15.4
frequency range is discussed briefly in Section 3. Simulation set up has been discussed in Section 4. Simulation
results have been discussed in Section 5. Finally, we conclude our work in Section 6.
2. RELATED WORK
According to our best knowledge, there exist only few articles [6] that analyze mathematically or simulate the
performance of IEEE 802.15.4. The performance of IEEE 802.15.4 in a star network with 100 nodes was
analyzed in [7]. The paper contained a compact mathematical analysis of average power consumption and
transmission failure rate. The analysis was complemented with real measurements of steady state powers and
transient energy, and switch times from a standard compliant evaluation board. A special contribution was bit
error rate measurements with two evaluation boards connected through a set of calibrated attenuators. The
operational analysis considered mainly the effect of path loss and packet size on energy consumption.

J. Zheng and M.J. Lee [8] implemented the IEEE 802.15.4 standard on NS2 simulator and provided the
comprehensive performance evaluation on 802.15.4. The literature comprehensively defined the 802.15.4
protocol as well as simulations on various aspects of the standard. It mainly confined to performance of IEEE
802.15.4 MAC.

The authors provided performance evaluations of IEEE 802.15.4 MAC in beacon-enabled mode for a star
topology [9]. The performance evaluation study revealed some of the key throughput-energy-delay tradeoff
inherent in IEEE 802.15.4 MAC. The performance of IEEE 802.15.4 was analyzed for medical sensor body area
networking [10]. The analysis considered quite extensively a very low data rate star network with 10 body
implanted sensors transmitting data 1 to 40 times per hour. The analysis focused on the effect of crystal
tolerance, frame size, and the usage of IEEE 802.15.4 Guaranteed Time Slots (GTS) on a node lifetime. For
analyzing the standard performance in WSN applications, further analysis with larger and more complex
network topologies and other IEEE 802.15.4 MAC parameters would be required.

The authors presented a novel mechanism intended to provide Quality of Service (QoS) for IEEE 802.15.4
based Wireless Body Sensor Networks (WBSN) used for pervasive healthcare applications [11]. The
mechanism was implemented and validated on the Aquis Grain WBSN platform.

The performance simulations of IEEE 802.15.4 in a star network were presented [12]. The network consisted of
49 nodes configured to IEEE 802.15.4 beacon-enabled mode. The evaluation considered latency and energy
with different amounts of background traffic. Also, the performance of IEEE 802.15.4 GTS and beacon tracking
were simulated. Still, the applicability of the results for WSN applications was insufficient, since larger network
sizes with cluster tree network topologies were required.
3. ZIGBEE WIRELESS NETWORK
Zigbee is a group of protocols which is developed based on IEEE802.15.4 wireless communication
standard.[13,14] The goal of the standard is to meet the requirements for wireless home control, industrial
automatic control and remote control. It can be built in most of instruments and also support geographical
position.

IEEE802.15.4 is a low rate wireless Personal Area Network standard developed by IEEE. It defines the two
lower layers Physical layer and MAC layer. High level application, test and marketing promote are charged by
Zigbee alliance. Zigbee alliance was established in October, 2002. It consists of Holland Philips semiconductor
company, US Motorola, UK Invensys and Japanese Mitsubishi electric company and more. At present, the
number of members is over 175, which includes world leading semiconductor manufacturers, technology
providers, OEMs and end-users [15].

A complete Zigbee protocol set is made of high level application specification, application support sub-layer,
network layer, MAC layer and physical layer. To minimize the effects of interference, 802.15.4 uses direct
sequence spread spectrum. The standard defines two PHY layers suitable for three different frequency bands,



ISSN : 0975-5462                             Vol. 3 No. 2 Feb 2011                                           1590
                  Gurjit Kaur et al. / International Journal of Engineering Science and Technology (IJEST)


868 MHz (Europe), 915 MHz (USA) and 2.4 GHz (Worldwide) [16]. The two physical data package are of the
same format but of difference in work frequency, modulation technique, PN-code length and transmission rate.
2.4GHz physical layer could offer 250kb/s transmission rate by using high order modulation technique, which is
helpful to gain higher handling capacity, shorter transmission delay and work circle. Thus it can save more
energy.
                                        Table I: Frequency bands and data rates

                           Physical    Frequency     Channels       Bit rate      Modulation
                           layer       Band                         (Kbits/s)


                           868/915     868-870            0             20          BPSK
                           MHz         MHz
                                       902-928          1-10            40          BPSK
                                       MHz
                           2.4 GHz     2.4-2.4835       11-26          250         O-QPSK
                                       GHz

The stack above the network layer is defined by Zigbee alliance, it includes network layer and application layer
standard. The network layer supports three topologies: star, cluster tree, mesh topology. Additionally it defines
the Security Service Provider (SSP) that handles encryption and access control lists (ACL) to ensure secure
communication. The complete Zigbee stack architecture is shown in Figure.1[7]




                                           Figure 1: Zigbee architecture [7]

Zigbee networks use three device types [8]:

        The network coordinator maintains overall network knowledge. It is the most sophisticated of the three
         types and requires the most memory and computing power.
        The full function device (FFD) supports all 802.15.4 functions and features specified by the standard. It
         can function as a network coordinator, Additional memory and computing power make it ideal for
         network router functions.
        The reduced function device (RFD) carries limited (as specified by the standard) functionality to lower
         cost and complexity.

4. SIMULATION SETUP
The main objective of this simulation study was to analyze the effect of different modulation schemes like ASK
(Amplitude shift keying), BPSK (Binary phase shift keying) & QPSK (Quadrature phase shift keying) on the


ISSN : 0975-5462                              Vol. 3 No. 2 Feb 2011                                         1591
                  Gurjit Kaur et al. / International Journal of Engineering Science and Technology (IJEST)


performance of Zigbee home automation using static IEEE 802.15.4 star topology for varying parameters. The
simulations have been carried out using QualNet version 5.0, software which provides scalable simulations of
wireless networks.

In the simulation model, a star topology with one PAN co-ordinator, one PDA (personal digital assistants), and
10 devices are uniformly deployed in an area of 1500m x1500m. PAN is static mains powered device placed at
the centre of the simulation area. Only the uplink traffic i.e. devices to PAN co-ordinator are considered in the
simulations which suits WSN application like automation industry where a large number of devices
communicates to a single sink server for data delivery and processing. The transmission range of devices is one
hop away from PAN Coordinator in star topology. The fact that BO (Beacon order) = SO (super frame order)
assures that no inactive part of the super frame is present [15]. A low value of this parameter implies a great
probability of collisions of beacon frames as these would be transmitted very frequently by coordinators.




                               Figure2: Simulation setup of Zigbee home automation network

 On the contrary, a high value of the BO (beacon order) introduces a significant delay in the time required to
perform the MAC association procedure since channel duration which is a part of association procedure is
proportional to BO (beacon order). In our simulation model, function for acknowledging the receipt of packets
is disabled. It is due to the fact that overhead mechanism is too expensive for low data rate WSN application for
which 802.15.4 is designed. 

Following QoS performance metrics were used to evaluate QoS parameters for IEEE 802.15.4 star topology
using different modulation scheme:

Jitter is often known as a measure of the variability over time of the packet latency across a network. A network
with constant latency has no variation (or jitter). Packet jitter is expressed as an average of the deviation from
the network mean latency. Jitter refers to a variation in packet delay, resulting in differing packet inter-arrival
times or out-of-sequence packets or both

Average End-to-End delay indicates the length of time taken for a packet to travel from the CBR (Constant Bit
Rate) source to the destination. It represents the average data delay an application experiences during
transmission of data. The end-to-end delay is the time taken for a data packet to reach the destination node. The
delay for a packet is the time taken for it to reach the destination. And the average delay is calculated by taking
the average of delays for every data packet transmitted. The parameter comes into play only when the data
transmission has been successful.

Packet Delay= (Receive Time at Destination) –



ISSN : 0975-5462                              Vol. 3 No. 2 Feb 2011                                          1592
                  Gurjit Kaur et al. / International Journal of Engineering Science and Technology (IJEST)


                (Transmit Time at Source)

Average Delay= (Sum of all Packet Delays)/( Total Number
                Of Received Pkts)                 (16)

Throughput is the number of bits passed through a network in one second. It measures how fast data can pass
through an entity (such as a point or a network). The throughput of a node is measured by first counting the total
number of data packets successfully received at the node and computing the number of bits received, which is
finally divided by the total simulation runtime. The throughput of the network is finally defined as the average
of the throughput of all nodes involved in data transmission. Therefore, throughput can be stated as:

               Throughput of a Node = (Total Data Bits Received) /                  (Simulation Runtime)

Similarly the throughput for the network can be defined as:

Network Throughput = (Sum of Throughput of Nodes Involved in Data Trans.) / (Number of Nodes)              (17)

5. PERFORMANCE ANALYSIS
This section presents the simulation results to show the impact of various QOS metrics on different modulation
scheme like ASK, BPSK & QPSK at different frequency range by using CBR application on Zigbee home
automation network having static IEEE 802.15.4 star topology.




                         Figure3: QualNet animation during simulation execution of Zigbee auto home

The following table depicts comparison of modulation schemes at different frequency range based on CBR
applications on the application layer.




ISSN : 0975-5462                                Vol. 3 No. 2 Feb 2011                                       1593
                 Gurjit Kaur et al. / International Journal of Engineering Science and Technology (IJEST)


             Table II: Comparison of different modulation using CBR application in Zigbee home automation network

                                  Modulation             Thruou-         Avg. end     Jitter
                                  schemes                gput            to end
                                                                         delay
                                  QPSK                        95            3.32           0.43
                                  (2.4GHz)
                                  BPSK                        92            3.59           0.05
                                  (915MHz)
                                  ASK                         95            3.30           0.03
                                  (915MHz)
                                  BPSK                        94            7.90           0.67
                                  (868Hz)
                                  ASK                        100           10.07           0.98
                                  (868MHz)


Figure 4 shows the value of jitter for different modulation schemes. The ASK (amplitude shift keying), BPSK
(binary phase shift keying) modulation technique at 915MHz frequency produced the lowest value of 0.03s and
0.05s, QPSK produced high value of 0.43s, and BPSK and ASK at 868 MHz frequency produced highest value
of 0.67s and 0.98s respectively. So, in terms of jitter ASK at 915 MHz frequency performs better than other
modulation scheme since low jitter corresponds to high efficiency.


                                                              JITTER
                                       1.2

                                        1
                           JITTER(s)




                                       0.8

                                       0.6

                                       0.4

                                       0.2                                                 JITTER

                                        0
                                               QPSK         BPSK        ASK       BPSK        ASK
                                             (2.4GHz)     (915MHz)   (915MHz)   (868MHz)   (868MHz)

                                                        MODULATION SCHEME



              Figure 4: Impact of Jitter on various modulation scheme using CBR application of Zigbee auto home

Figure 5 shows the performance of average end-to-end delay for different modulation scheme at different
frequency ranges. The average end-to-end delay of a packet depends on delay at each hop comprising of
queuing, channel access and transmission delays as well as route discovery latency. BPSK at 915 MHz
produced average end-to-end delay value of 3.59s, QPSK and ASK at 915 MHz produced a significantly low
value of 3.32s and 3.30s whereas BPSK and ASK at 868 MHz produced higher values of 7.90s and 10.07s
respectively. So, in terms of average end-to-end delay ASK at 915 MHz frequency performs best since low
average end-to-end delay would lead to faster performance.




ISSN : 0975-5462                                        Vol. 3 No. 2 Feb 2011                                       1594
                   Gurjit Kaur et al. / International Journal of Engineering Science and Technology (IJEST)



                                                                                         Avg. end to end delay
                                                         12




                              Avg. end to end delay(s)
                                                         10

                                                                8

                                                                6

                                                                4                                                              Avg. end to 
                                                                2                                                              end delay
                                                                0
                                                                           QPSK            BPSK          ASK          BPSK           ASK
                                                                         (2.4GHz)        (915MHz)     (915MHz)      (868MHz)      (868MHz)

                                                                                         MODULATION
                                                                                           SCHEME


       Figure5: Impact of Average end to end delay on various modulation schemes using CBR application of Zigbee auto home

Figure 6 presents the performance of throughput for different modulation techniques at different frequency
range. According to our findings, BPSK at 915MHz produced a throughput value of 92%, BPSK at 868MHz
92%, QPSK, and ASK at 915MHz 95%, and ASK at 868MHz 100%. According to throughput results, ASK at
868 MHz performs best since it produces more output as compared to other modulation schemes.

                                                                                              Throughput

                                                                102
                                           THROUGHPUT(bits/s)




                                                                100


                                                                    98


                                                                    96


                                                                    94


                                                                    92                                                          Throughput

                                                                    90


                                                                    88

                                                                         QPSK (2.4GHz)      BPSK     ASK (915MHz)     BPSK     ASK (868MHz)
                                                                                          (915MHz)                  (868MHz)



                                                                                         MODULATION
                                                                                           SCHEME


              Figure 6: Impact of throughput on various modulation scheme using CBR application of Zigbee auto home

6. CONCLUSION
This paper has presented a preliminary performance study of the IEEE 802.15.4 wireless standard via simulation
results. Results show the effects on QoS parameter by using different modulation schemes at different frequency
range like ASK, BPSK and QPSK by using CBR application in Zigbee home automation network having static
IEEE 802.15.4 star topology. Quality of service metrics (average end-to-end delay, throughput, jitter) are used
to compare to different modulation schemes. The findings suggest that although ASK at 868 MHz produce a
little higher throughput than all other modulation schemes which makes it a suitable choice for Zigbee home
automation network but still ASK at 915MHz is the best suited protocol for CBR application of Zigbee home
automation network because of the fact that ASK at 868 MHz throughput value is not significantly higher than
ASK at 915MHz. Also, ASK at 915 MHz performs better overall and produce less jitter and average end to end
delay as compared to all other modulation schemes.




ISSN : 0975-5462                                                                    Vol. 3 No. 2 Feb 2011                                     1595
                      Gurjit Kaur et al. / International Journal of Engineering Science and Technology (IJEST)


7. REFERENCES

[1] Y.-C. Tseng, S.-P. Kuo, H.-W. Lee, and C.-F. uang Location tracking in a wireless sensor network by mobile agents and its data fusion
     strategies. In Proc. of Int’l Sympon Information Processing in Sensor Networks (IPSN), volume 2634, pages 625-641, 2003.
[2] Y.-C. Tseng, M.-S. Pan, and Y.-Y. Tsai. Wireless sensor networks for emergency navigation. volume 39, pages 55–62, 2006.
[3] IEEE standard for information technology- telecommunications and information exchange between systems - local and metropolitan
     area networks specific requirements part 15.4: wireless medium access control (MAC) and physical layer (PHY) specifications for low-
     rate wireless personal area networks (LR-WPANs), 2003.
[4] IEEE Std 802.15.4 2006 Part 15.4, “Wireless Medium Access Control (MAC) and Physical Layer (PHY) Specifications for low-Rate
     Wireless Personal Area Networks (LR-WPANs),” 2006.
[5] E. Callaway et al., "Home Networking with IEE802.15.4: A developing Standard for Low-Rate Wireless Personal Area Networks,”
     IEEE Communications Magazine, Vol. 40 No. 8, pp 70-77, Aug. 2002.
[6] J. Zheng and Myung J. Lee, “A comprehensive performance study of IEEE 802.15.4,” Sensor Network Operations Book, IEEE Press,
     Wiley Interscience, Chapter 4, pp. 218-237, 2006.
[7] Bougard, B., Catthoor, F., Daly, D.C., Chandrakasan, A.,Dehaene, W., “Energy efficiency of IEEE 802.15.4               standard in dense
     wireless microsensor networks:          modeling and improvement perspectives”, in Proceedings        of Design, automation and test in
     Europe (DATE’05) (Munich, Germany, March 7-11, 2005). IEEE, 2005, Vol.                1, 196-201.
[8] G. Lu, B. Krishnamachari, and C.S. Raghavendra,             “Performance evaluation of the IEEE 802.15.4 MAC for low-rate low power
     wireless networks,” in Proceedings of         the 23rd IEEE International Performance Computing and        Communications Conference
     (IPCCC '04), Pages 701-         706, Phoenix, Ariz, USA, April 2004.
[9] Timmons, N.F., Scanlon, W.G., “Analysis of the            performance of IEEE 802.15.4 for medical sensor body      area networking”, in
     Proceedings of the 1st IEEE international conference. On Sensor and ad hoc communications and networks (SECON’04) (Santa
     Clara, CA, USA, 4-7. October, 2004). IEEE, 2004, 16-24.
[10] Jose Javier Garcia, Thomas Falck, “Quality of Service              for IEEE 802.15.4 based Wireless Body Sensor          Networks," 3rd
     International Conference on Pervasive        Computing Technologies for Healthcare, Pages 1-6, 1-3     April 2009
[11] Lu, G., Krishnamachari, B., Raghavendra, C.S.,         “Performance evaluation of the IEEE 802.15.4 MAC for         low-rate low-power
     wireless networks, in Proceedings of           the 23rd IEEE international Performance computing and        communications conference
     (IPCCC’04)”, (Phoenix, AZ, USA, April 15-17, 2004). IEEE, 2004, 701-706.
[12] Sanatan Mohanty, “Energy Efficient Routing Algorithms           for Wireless Sensor Networks and Performance      Evaluation of Quality
     of Service for IEEE 802.15.4        Networks “, M. Tech thesis, NIT Rourkela, 2010.
[13] P. Kinney. ZigBee Technology: Wireless Control that Simply Works, White Paper dated 2 October 2003.
[14] Shigeru Fukunaga Et Al. Development of Ubiquitous Sensor Network, Oki Technical Review, Vol.7 1, No.3, pp. 24-29, October 2004
[15] ZigBee Alliance. http://www.zigbee.org/en/press
[16] William C Craig. ZigBee: "Wireless Control That Simply Works". http://www.zigbee.org
[17] Michal VARCHOLA, Miloš DRUTAROVSKÝ” ZIGBEE BASED HOME AUTOMATION WIRELESS SENSOR NETWORK” Acta
     Electrotechnica et Informatica No. 4, Vol. 7, pages 1-8, 2007




ISSN : 0975-5462                                       Vol. 3 No. 2 Feb 2011                                                         1596

				
DOCUMENT INFO
Shared By:
Tags: Zigbee
Stats:
views:24
posted:9/28/2011
language:English
pages:8
Description: Zigbee is synonymous with the IEEE 802.15.4 protocol. According to the agreement of the technology is a short distance, low-power wireless communication technology. The name comes from the bee character dance, as bees (bee) is flying by and the "buzz" (zig) shake the wings of the "dance" to transfer pollen with peers where the position information in such a way that bees rely on constitute a group communication network. Its characteristics are close, low-complexity, self-organizing, low power, low data rate, low cost. Mainly suitable for automatic control and remote control, can be embedded in various devices. In short, ZigBee is a cheap, low-power short-range wireless network communication technology group.