Submission Title: [Distributed Contention Access Scheme] Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [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 Basis of Distributed Contention Access The Features of Communication in WPAN low data rate and small packets of a single node Large number of nodes CSMA/CA mechanism: slotted and unslotted ones. Based on the features and the throughput calculation method, the optimization of CAP is derived from －The Distributed CAP Submission Pei Liu, Hisilicon.

The Distributed Contention Access Scheme 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 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 Procedure of optimal contention access Submission Pei Liu, Hisilicon.

The Distributed Contention Access Scheme 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.

Simulation Results of the CAP Optimization The initial number of devices is 5; and 80s later, additional 15 devices are connected into the network Submission Pei Liu, Hisilicon.

Simulation Results of the CAP Optimization The initial number of devices is 5; and 80s later, additional 35 devices are connected into the network Submission Pei Liu, Hisilicon.

Summary By the CAP optimization, 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.

Conclusion The proposed non-persistent CSMA mechanism based on the new CAP channel model reasonably reduces the complexity of CCA analysis, and improves the accuracy of throughput by considering the influence of timeout period. Based on the features of WPAN and proposed np-CSMA, a CAP optimization scheme is derived to obtain the optimal throughput. Submission Pei Liu, Hisilicon.