In this paper, the authors analyze the performance limits of the slotted CSMA/CA mechanism of IEEE 802.15.4 in the beacon-enabled mode for broadcast transmissions in WSNs. They analyze for different network settings to understand the impact of the protocol attributes (superframe order, beacon order and backoff exponent) namely in the terms of *throughput(S), average delay (D), probability success(Ps) and introduce the concept of utility(U)*.

**Simulation model :**

They use the default wireless models of OPNET library for emulating the background noise, propagation delay, radio interferences, received power, bit error rate, etc.

Simulation test-bed :

They consider a typical wireless sensor network in a surface of (100 m X 100 m) with one PAN coordinator and 100 identical nodes (randomly spread) generating Poisson distributed arrivals, with the same mean arrival rate. Note that the Poisson distribution is typically adopted by most simulation and analytical studies on CSMA/CA. They assume that SO = BO (100 % duty cycle). No hidden-terminal problem.

**Performance evaluation of slotted CSMA/CA under different settings :**

1. Impact of SO and BO

– The network throughput as a function of the offered load for different (BO,SO) values.

– Success probability as a function of the offered load for different (BO,SO) values.

– The average delay as a function of the offered load for different (BO,SO) values.

– The average delay as a function of the offered load (G) for different (BO,SO) in the range G = [0, 40%]

– Utility(U) as a function of the offered load for different (BO,SO) values.

2. Impact of macMinBE

– the network throughput as a function of the offered load for different macMinBE values.

– the success probability as a function of the offered load for different macMinBE values.

– the network throughput as a function of the offered load for different macMinBE values with 10 nodes.

– Gmac as a function of the offered load for different macMinBE values with 10 nodes.

– the success probability as a function of the offered load for different macMinBE values with 10 nodes.

– the average delay as a function of the offered load for different macMinBE values with 100 nodes.

– the utility as a function of the offered load for different macMinBE values.

**Future work :**

– consider the hidden-terminal problem

– using simulator NS2

**Reference :**

A Comprehensive Simulation Study of Slotted CSMA/CA for IEEE 802.15.4 Wireless Sensor Networks.

Anis KOUBAA et all – IPP-HURRAY

Note : This resume is created for self-learning only. Author and Publisher hold copyrights

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*Maret 03, 2008*

*Taipei City
High Speed Network Lab*

Udin Harun