Project: IEEE P Working Group for Wireless Personal Area Networks (WPANs)

Transcription

1 doc.: IEEE c Project: IEEE P Working Group for Wireless Personal Area Networks (WPANs) Title: [Low latency aggregation] Date Submitted: [March 18, 2007] Source: [Zhou Lan, Chang-woo Pyo, Fumihide Kojima, Hiroyuki Nakase, Shuzo Kato, Gal Basson (2) ] Company [National Institute of Information and Communications Technology (NICT),Wilocity (2) ] Address 1 [3-4 Hikari-no-oka, Yokosuka-shi, Kanagawa , Japan] Voice 1 :[], FAX 1 : [] [lan@nict.go.jp, other contributors are listed in Contributors slides] Re: [In response to TG3c comments (IEEE P c)] Abstract: [Comment resolutions] Purpose: [To be considered in TG3C baseline document.] 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 contributors acknowledge and accept that this contribution becomes the property of IEEE and may be made publicly available by P

2 Comment # 43, 44, 47 Comment #43 Enable aggregation Comment#44 Enable Block Ack to be aggregated with data Comment #47 Enable CTA to be bi-directional (meaning interchanging transmissions between 2 DEV at the same CTA) Response The necessary information is provided in the following presentation 2

3 Summary To support application which requires low latency bidirectional communication such as USB,PCI express, USB, esata or wireless docking, a low latency A- aggregation method is proposed. System requirement c-draft-tg3c-system-requirements A- aggregation Use of Bi-Directional CTA (using the CTA relinquish bit) Frame format One bit in the PHY header to indicate the Bi-Directnal low latency mode Adding BA field in the MAC The aggregation procedure can be easily accommodated in the current SC proposal with only 1 extra bit indication in PHY header 3

4 preamble preamble Low latency aggregation It is assumed that (4octets ~256octets) containing data which comes from upper layer, usually in a burst distribution. MAC, upon receiving a, attaches each a and, directly sent them out without waiting for the following s to be aggregated When the coming didn t arrive on time, idle data can be transmitted to fill the gap between real s (zeros as example) Idle is at a size of D-words multiplication. #2 #3 #4 L #1 #4 ranging from 4 octets 256octets #3 Idle MAC #2 Base header MAC #1 Base header MAC #1 #2 Idle data #3 #4 PHY 4 time

5 A- Header Definition Subframe#1 Subframe#2... Subframe#n number (10 bits) length [Dwords] (6 bits) Header - (8 bits) sequence Number 10 bits Length Length in DWords Units [6 bits] -- header checksum [8 bits] Idles can be inserted as zero transmission is between s Header will be identified by searching a pattern which corresponds to the - In the case of header error, a new header can be identified 5

6 BA map preamble MAC SUbHeade r preamble Low latency A aggregation frame format 2 different frame formats one for standard mode the other for low latency mode s are encapsulated in between subframes (low latency mode) Subframe length ranges from 4 octets to 256 octets (low latency mode) Maximum number of aggregated s is 256 Idles are transmitted in between s header is identified using the header Standard aggregation mode MCS information (5 bits) information (1 bit) Retransmission (1 bits) Retry bit (1 bit) Resolution indication (1 bit) Subframe length (11 bits) Subframe information (2 bits) Skewed Constellation mode (1bit) offest (3 bit) Last fragmentation (1 bit) Reserved (5 bit) Base header Subframe #1 Subframe #2... Subframe #n 1 octet to 1Moctets Up to 8 subframe 1 bit in Base header to indicate using Bi Directional low latency mode number (10 bits) length [Dwords] (6 bits) Header - (8 bits) Low latency mode Base header Subframe#1 Subframe#2... Subframe#n 4 octet to 256 octets Up to 256 s 6

7 Comment# 44 -Bi-directional data transmission When the Bi-directional low latency mode is set Will be block ack Block ACK Will be part of the MAC Each bit represent individual number Transmitter BA #1 Aggregated Frame #2 #3 #4 #5 #6 BA #2 Aggregated Frame #4 #7 #8 #9 #10 Receiver SIFS BA Aggregated Frame # 1' # 2' # 3' # 4' # 5' SIFS #1 (ACK) Blk-ACK bit map #2 (NAK) #3 (ACK) #4 (NAK) #5 (ACK) #6 (ACK) 7

8 2008/3/20 CRC suggested ( ) The header CRC that will be used is: Polynomial equal to X^8+X^2+X+1 Example of implementation: 8

9 Frame format for Bi Directional Low PHY Header addition Low latency mode bit when set: Latency mode the MAC will be transmitted using the same MCS as the data When set to 0 Standard aggregation mode Use CTA relinquish bit (MAC Header) to handover the control to the Destination device, and visa versa When UEP Field bit7 (UEP_Enable) set to zero Subframe#1 ACK/NAK Subframe#2 ACK/NAK... Subframe#256 ACK/NAK preamble PHY header (5 octets) MAC header (10 octets) UEP Field 1 byte BA bitmap (32/octets) #1 #2... #n MAC n up to 256 number (10 bits) Subframe length Dwords (6 bits) H (8 bits)

10 MAC in the case of low UEP Field latency mode Bit7- UEP_Enable if set UEP low latency mode is enabled BA MAP field is 64 octets, 32 first octets are for MSB the last 32 octets are for LSB Bits 6-2 UEP MCS Bits Reserved S u b f r a m e # 1 M S B S u b f r a m e # 2 M S B... S u b f r a m e # M S B S u b f r a m e # 1 L S B S u b f r a m e # 2 L S B... S u b f r a m e # L S B p r e a m b l e P H Y h e a d e r ( 5 o c t e t s ) M A C h e a d e r ( 1 0 o c t e t s ) H C S U E P F i e l d 1 b y t e B A b i t m a p ( 6 4 o c t e t s ) H C S M S D U S u b h e a d e r ( 3 o c t e t s ) M S D U # 1 F C S S u b h e a d e r M S D U ( 3 o c t e t s ) M S D U # 2 F C S... M S D U S u b h e a d e r ( 3 o c t e t s ) M S D U # n F C S MAC n u p t o M S D U n u m b e r ( 1 0 b i t s ) S u b f r a m e l e n g t h D w o r d s ( 6 b i t s ) 10 M S D U H H C S ( 8 b i t s )