1. Submission Title: [Distributed Contention Access Scheme]
Project: IEEE P Working Group for Wireless Personal Area Networks (WPANs)
Submission Title: [Distributed Contention Access Scheme]
Date Submitted: [Nov ]
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:[ ],
Re: [ IEEE c ]
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 P 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 P
Submission
Pei Liu, Hisilicon.

2. 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.

3. 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.

4. 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.

5. 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.

6. 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.

7. 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.

8. 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.

9. 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.