Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)

1. Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [Non-persistent CSMAMechanism] 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. Paul Dixon, Pei Liu, Hisilicon

2. The CSMA/CA Operation Procedure in IEEE 802.15.4-2006 MAC • The CSMA/CA algorithm is used within CAP in IEEE802.15.4-2006 MAC, may operate in either of two topologies: the star topology or the peer-to-peer topology. • The network throughput is an important evaluation for the performance of CSMA/CA. • In IEEE802.15.4-2006, the procedure is derived from CSMA/CA mechanism of the IEEE802.11 Standard Paul Dixon, Pei Liu, Hisilicon

3. Drawbacks of Current MAC Protocol • The CSMA/CA mechanism in WPAN is quite different from IEEE802.11: • The virtual carrier-sense mechanism, and the RTS（request-to-send ）/CTS（clear-to-send) are not employed in WPAN, because of the low data rate, short packets, and high ratio of packet header and control packets to payload data for a single node, compared to 802.11. • Only the slotted CSMA/CA is employed in 802.11, but in WPAN, slotted and unslotted CSMA/CA may be employed, depending on the network modes. Therefore, a large error may result from calculation of successful CCA probability and throughput. Furthermore, the computational complexity of successful CCA probability and throughputarequite high. Paul Dixon, Pei Liu, Hisilicon

4. Definition of Networking Throughput • The throughput is defined as the proportion of time to successfully transmit payload bits in the investigated cycle, the period between two successful packet transmissions. Where Tpis thetime to successfully transmit payload bits in the investigated cycle, Tvis the period between two successful packet transmissions, shown as the CAP channel model. Paul Dixon, Pei Liu, Hisilicon

5. Promoting Non-persistent CSMA/CA • The CSMA/CA algorithm in WPAN is similar to non-persistent CSMA. It’s feasible to apply np-CSMA for analyzing the WPAN CSMA/CA processing and confirming the throughput on WPAN. Paul Dixon, Pei Liu, Hisilicon

6. Communication Model on one Channel Communication Model in one Channel Acquire the average idle time in communications, and average collision times between successful communications in consideration of timeout. Paul Dixon, Pei Liu, Hisilicon

7. confirm the time parameters calculate the throughput calculate average collision times in a cycle calculate the cycle calculate the throughput Calculation Throughput • Build up the Markov model for accessing channel. Calculate the possibility of accessing the channel (such as the ratio of successful CCA, the possibility of first CCA in back off period), and one of two consecutive successful CCA. • Calculate the throughput based on the CAP model and parameters. Paul Dixon, Pei Liu, Hisilicon

8. slotted CSMA/CA (step1) NB=0,CW=2 Y Battery life BE=min（2,mac MinBE) extension？ N BE=mac MinBE Locate backoff period boundary Delay for random (step2) (0~2BE -1) unit backoff periods (step3) Perform CCA Y Channel idle？ N (step5） CW=2,NB=NB+1 (step4) CW=CW-1 BE=min(BE+1, aMaxBE ) N N NB> CW=0? macMaxCSMABackoffs? Y Y failure success The Non-persistent Slotted CSMA/CA Algorithm Paul Dixon, Pei Liu, Hisilicon

9. The Non-persistent Unslotted CSMA/CA Algorithm Paul Dixon, Pei Liu, Hisilicon

10. Simulation Results of the Throughput Within CAP under CSMA Method • Supposed: • One coordinator and end devices with a star topology • The number of devices is fixed and known • Other conditions strictly follow the ones in the CSMA/CA algorithm in IEEE802.15.4 Paul Dixon, Pei Liu, Hisilicon

11. Simulation Results of the Throughput Within CAP under CSMA Method • The details of the simulation conditions: • Other parameters use the default values defined for 2.4GHz frequency channels such as 3, 5 and 4 for macMinBE, aMaxBE and macMaxCSMABackoff, respectively. Paul Dixon, Pei Liu, Hisilicon

12. Simulation Results of the Throughput Within CAP under CSMA Method Where L is the number of payload slots within CAP Paul Dixon, Pei Liu, Hisilicon

13. The Features of Non-persistent CSMA/CA • Large reduction of the complexity of CAP analysis • Much accuracy CCA assessing with low complexity, based on the new communication model on one channel • Much accuracy evaluation of throughput in consideration of timeout. Paul Dixon, Pei Liu, Hisilicon