1. Submission Title: [The Distributed Contention Access Scheme]
Project: IEEE P Working Group for Wireless Personal Area Networks (WPANs)
Submission Title: [The 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 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.

3. 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.

4. 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.

5. 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.

6. 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.

7. 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 std
Submission
Pei Liu, Hisilicon.

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

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

10. 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.