Submission Title: [The Distributed Contention Access Scheme] Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [The Distributed Contention Access Scheme] Date Submitted: [Nov. 2006 ] Source: [Pei Liu, Liang Li ] Company: [Hisilicom Technology Co. Ltd, Vinno Technologies Inc. ] Address: [Nan Tian Bld., No.10 Xinxi. Rd Shang-Di Information Industry Base, Hai-Dain District, Beijing,China ] Voice:[86-10-82882552], E-Mail:[liupei@hisilicon.com, liangli@vinnotech.com] Re: [ IEEE 802.15.4c ] Abstract: [Description the upgraded MAC issues on Chinese WPAN Standard Draft] Purpose: [To encourage discussion.] Notice: This document has been prepared to assist the IEEE P802.15. It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein. Release: The contributor acknowledges and accepts that this contribution becomes the property of IEEE and may be made publicly available by P802.15. Submission Pei Liu, Hisilicon.

The Features of WAPN Communication low data rate and small packets of a single node Large number of nodes CSMA/CA mechanism: slotted and unslotted ones. It is necessary to optimize the CAP scheme to obtain the efficient network throughput The optimization of CAP scheme is based on the CAP model and the efficiency of throughput Submission Pei Liu, Hisilicon.

Promoting Distributed Contention Access Distributed CAP is promoted to optimize the CAP scheme for: The channel model within CAP; And The performance of network throughput; And Efficiency of total energy utilization of network Submission Pei Liu, Hisilicon.

The Distributed Contention Access Scheme (1) The model of CAP optimization optimization of network calculate the back off number optimization get the time parameters calculate successful CCA probability get the network parameters Submission Pei Liu, Hisilicon.

The Distributed Contention Access Scheme (2) The detail CAP optimization steps： Get the number of devices in the network using the CAP channel model. Calculate the back off number to get optimal network throughput. Optimize the device number in CAP period based on the result of 2nd step Submission Pei Liu, Hisilicon.

The Distributed Contention Access Scheme (3) Procedure of optimal contention access Get the parameters of a cycle Calculate throughput and average cycle length Calculate optimal back off number Calculate the probability of successful CCA Estimate the device number based on average successful CCA probability Revise the device number in the every successful CCA cycle Optimize the network Submission Pei Liu, Hisilicon.

Simulation Results of the CAP Optimization (1) Supposed: Some of devices transmit the fixed size packets to the coordinator simultaneously, and Each device can use the distributed CAP for optimization. The initial number of devices is 5, and 80s later, some additional devices are connected into the network Other conditions strictly pursue the ones in CSMA/CA procedure in 802.15.4 std Submission Pei Liu, Hisilicon.

Simulation Results of the CAP Optimization (2) Case 1: 15 additional devices become active Submission Pei Liu, Hisilicon.

Simulation Results of the CAP Optimization (3) Case 2: 35 additional devices become active Submission Pei Liu, Hisilicon.

Simulation Summary By the CAP optimization from Distributed Contention Access, the throughput of network will reach a new stable optimal value after short-lived fluctuation, even though the device number changes sharply By the optimization of CAP and throughput, the efficiency of total energy utilization of WPAN is improved. Submission Pei Liu, Hisilicon.