1. Mar 2008 doc:IEEE802. 15-08-0147-00-004e Slide 1 Submission Paul Dixon, Pei Liu, Hisilicon. Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [ Distributed Contention Access Scheme ] Date Submitted: [Mar 2008 ] Source: [Paul Dixon, 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:[+1 469 229 5374], E-Mail:[pdixon@huawei.com, liupei@hisilicon.com, liangli@vinnotech.com] Re: [ IEEE 802.15.4e ] 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.

2. Mar 2008 doc:IEEE802. 15-08-0147-00-004e Slide 2 Submission Paul Dixon, Pei Liu, Hisilicon. The Features of WPAN Communication  low data rate and small packets from a single node  Large and variable number of nodes  CSMA/CA mechanism: slotted and unslotted It is Necessary to Optimise the CAP Scheme to optimize the network throughput We must consider the Feasibility of Optimising the CAP Scheme (based on the CAP model and calculation method of throughput)

3. Mar 2008 doc:IEEE802. 15-08-0147-00-004e Slide 3 Submission Paul Dixon, Pei Liu, Hisilicon. The Current Scheme In the above scenario, it works efficiently only only over a small range of load As the number of competitors for access to the channel varies, there can be large swings in throughput and efficiency The optimum range of back off values varies with the number of competitors for access For efficient operation over the full range of loads, back of limits must be variable

4. Mar 2008 doc:IEEE802. 15-08-0147-00-004e Slide 4 Submission Paul Dixon, Pei Liu, Hisilicon. Distributed Contention Access Distributed CAP is proposed to optimise the CAP scheme for: The channel model within CAP; And The calculation method of network throughput; And The performance of network throughput; And Efficiency of total energy utilisation of network

5. Mar 2008 doc:IEEE802. 15-08-0147-00-004e Slide 5 Submission Paul Dixon, Pei Liu, Hisilicon. The Distributed Contention Access Scheme (1) The model of CAP optimisation optimisation of network calculate the back off number optimisation get the time parameters calculate successful CCA probability get the network parameters

6. Mar 2008 doc:IEEE802. 15-08-0147-00-004e Slide 6 Submission Paul Dixon, Pei Liu, Hisilicon. The detail CAP optimisation steps ： 1.Get the number of devices in the network using the CAP channel model. 2.Calculate the back off number to get optimal network throughput. 3.Revise the device number in CAP period based on the result of 2 nd step The Distributed Contention Access Scheme (2)

7. Mar 2008 doc:IEEE802. 15-08-0147-00-004e Slide 7 Submission Paul Dixon, Pei Liu, Hisilicon. The Distributed Contention Access Scheme (3) 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

8. Mar 2008 doc:IEEE802. 15-08-0147-00-004e Slide 8 Submission Paul Dixon, Pei Liu, Hisilicon. Simulation Results of the CAP Optimisation (1) Supposed: Some devices transmit fixed size packets to the coordinator simultaneously, and Each device can use the distributed CAP for optimisation. The initial number of devices is 5, and 80s later, some additional devices are connected into the network Other conditions strictly follow the ones in CSMA/CA procedure in 802.15.4 std

9. Mar 2008 doc:IEEE802. 15-08-0147-00-004e Slide 9 Submission Paul Dixon, Pei Liu, Hisilicon. Simulation Results of the CAP Optimisation (2) Case 1: 15 additional devices become active

10. Mar 2008 doc:IEEE802. 15-08-0147-00-004e Slide 10 Submission Paul Dixon, Pei Liu, Hisilicon. Simulation Results of the CAP Optimisation (3) Case 2: 35 additional devices become active

11. Mar 2008 doc:IEEE802. 15-08-0147-00-004e Slide 11 Submission Paul Dixon, Pei Liu, Hisilicon. Simulation Summary  By CAP optimisation using 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 optimisation of CAP and throughput, the efficiency of total energy utilisation of WPAN is improved.