1. Submission Title: [MAC Performance enhancements for Alt-PHY]
<January 2002>
doc.: IEEE <02/139r0>
November, 2002
Project: IEEE P Working Group for Wireless Personal Area Networks (WPANs)
Submission Title: [MAC Performance enhancements for Alt-PHY]
Date Submitted: November 13, 2002
Source: [Chuck Brabenac] Company: [Intel]
Address: [2111 NE 25th Ave, Hillsboro, OR 97124]
Voice: [ ], FAX: [ ],
Re: [02/105r20 clause 4]
Abstract: [Illustrates and justifies the need for various MAC performance enhancement modifications to support the a alt-PHY]
Purpose: [To set context for discussion of 02/105r20 clause 4]
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.
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Chuck Brabenac, Intel R&D
Chuck Brabenac, Intel Labs

2. Overview: 15.3a MAC performance enhancement need
November, 2002
Overview: 15.3a MAC performance enhancement need
15.3 MAC currently supports <=55Mb/s PHY
Its throughput efficiency can be very high
15.3a PHY will be 110, 200 & scalable to 480Mb/s+
On the order of 10x+ PHY rate increase
Reasonable to expect MAC performance enhancements to preserve throughput efficiency
15.3a CFA responses cited heavy MM needs
MPEG-2, MPEG-4 movies, etc.
We should assure the MAC can carry this traffic efficiently & reliably
Chuck Brabenac, Intel R&D

3. Simple “best case” CFP analysis at higher rates (1)
November, 2002
Simple “best case” CFP analysis at higher rates (1)
PHY parameter assumptions (pure fiction for now)
20us preamble (02/105r20 target)
10us SIFS (from 15.3 D14-pre)
22 Mb/s base rate
Error-free channel
Application/flow assumptions
Single flow, consuming nearly entire SF
Ignored beaconing, guard time, tail symbols, stuff bits
Calculations made at 55,110,200,480 and 1000 Mb/s:
Immediate ACK policy
Delayed ACK policy on 16 packets w/ SIFS
Delayed ACK policy on 16 packets w/ MIFS
Delayed ACK policy on 16 packets w/ MIFS and no preamble on subsequent frames of a burst
Chuck Brabenac, Intel R&D

4. Simple “best case” CFP analysis at higher rates (2)
November, 2002
Simple “best case” CFP analysis at higher rates (2)
Chuck Brabenac, Intel R&D

5. Simple “best case” CFP analysis at higher rates (3) Some Observations
November, 2002
Simple “best case” CFP analysis at higher rates (3) Some Observations
Delayed ACK/MIFS developed by TG3 team helps significantly
PHY preamble overhead remains a dominant factor to deal with at higher rates (~22%)
To scale upward, we should consider reducing/eliminating it on delayed ACK bursts
Chuck Brabenac, Intel R&D

6. Improving multimedia performance
November, 2002
Improving multimedia performance
Minor changes can reduce job failure rates of multimedia flows (e.g., MPEG-4)
Flow queue depth field could be added, enabling more effective scheduler (SRPT, etc.)
Effectively increases capacity of the MAC for this type of dynamic flow rate traffic (see next foil)
Refer to 02/297r1 QoS performance analysis and simulation results for more info
Chuck Brabenac, Intel R&D

7. Improving multimedia performance
November, 2002
Improving multimedia performance
~95% Channel utilization
70% Average performance
improvement over MAC
Chuck Brabenac, Intel R&D

8. November, 2002
Summary
15.3a MAC performance enhancements are necessary as PHY data rates scale upward
Justifies needed MAC modifications as per 02/105r20, clause 4
Chuck Brabenac, Intel R&D