1. Submission Title: [Non-persistent CSMA Mechanism]
Project: IEEE P Working Group for Wireless Personal Area Networks (WPANs)
Submission Title: [Non-persistent CSMA Mechanism]
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: [This document is an updated version of 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 CSMA/CA Operation Procedure in IEEE 802.15.4-2006 MAC
The CSMA/CA algorithm is used within CAP in IEEE MAC, which may operate in either of two topologies: the star topology or the peer-to-peer topology.
The network throughput is a important evaluation for the performance of CSMA/CA.
In IEEE , the throughput is derived from CSMA/CA mechanism of IEEE Standard
Submission
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
Only the slotted CSMA/CA is employed in , 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 success CCA probability and throughput. Furthermore, the computational complexity of success CCA probability and throughput are quite high.
Submission
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 Tp is the time to successfully transmit payload bits in the investigated cycle, Tv is the period between two successful packet transmissions, shown as the CAP channel model.
Submission
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.
Submission
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.
CAP is an typical linear Markov process with periodic feature with the following reasons. In IEEE CSMA/CA procedure，a device should sense channel before transmitting data. As the channel is idle, device transmit data on this channel. Or, device may back off basing on the backoff algorithm and sense channel again. However, each device and each time of sensing channel are independent.
Submission
Pei Liu, Hisilicon

7. Calculation Throughput
calculate the throughput
calculate the cycle
confirm the time parameters
calculate average collision times in a cycle
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 ones of two consecutive successful CCA.
Calculate the throughput based on the CAP model and parameters.
Submission
Pei Liu, Hisilicon

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

9. Same Procedure for non-persistent CSMA/CA and the original CSMA/CA
UnSlotted CSMA/CA Algorithm
Submission
Pei Liu, Hisilicon

10. So it is compatible with 15.4-2006.
Same protocol, Primitives and Parameters for non-persistent CSMA/CA and Original CSMA/CA
The Non-persistent CSMA/CA is one proposed procedure instead of the original CSMA/CA in std. The same protocol is applied too. In other word, the proposed non-persistent CSMA/CA don’t change the protocol.
Therefore, all of primitives, parameters and conditions strictly pursue the ones in the CSMA/CA algorithm in IEEE
So it is compatible with
Submission
Pei Liu, Hisilicon

11. Example of the Throughput simulation Within CAP
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.
packet payload
55 or 115 bytes
overhead
15 bytes
ACK length
11 bytes
Channel bit rate
250 kbps
Backoff unit
10 bytes
CCA time
4 bytes
Submission
Pei Liu, Hisilicon

12. Example of the Throughput simulation Within CAP
The L is the number of payload slots within CAP
Submission
Pei Liu, Hisilicon

13. The Features of Non-persistent CSMA/CA
Supplying a much simpler and more accurate analyzing method for CAP in WPAN than the current 15.4 CSMA/CA
it is compatible with original CSAM/CA in with
having the same procedure
having the same protocol.
having the same primitives, parameters and conditions
Submission
Pei Liu, Hisilicon