1. September 2003
Project: IEEE P Working Group for Wireless Personal Area Networks (WPANs)
Submission Title: MAC enhancement considerations for multimedia streaming
Date Submitted: September 17th, 2003
Source: Wonyong Yoon, Yong Suk Kim, Kisoo Chang, Samsung Advanced Institute of Technology
Address Suwon, Kyunggi-do, South Korea
Voice: , FAX: ,
Re: []
Abstract: The document suggests some enhancement points for 15.3 MAC to be used for multimedia streaming applications.
Purpose: [Discussion on MAC enhancements for multimedia streaming]
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
Yoon et al., MAC enhancement considerations for multimedia streaming

2. MAC Enhancement Considerations for Multimedia Streaming
September 2003
MAC Enhancement Considerations for Multimedia Streaming
September 17, 2003
Samsung (SAIT)
Yoon et al., MAC enhancement considerations for multimedia streaming

3. Issues QoS Network utilization Network throughput Piconet formation
September 2003
Issues
QoS
Network utilization
Network throughput
Piconet formation
Yoon et al., MAC enhancement considerations for multimedia streaming

4. September 2003
QoS
IEEE provides QoS by adopting TDMA architecture with channel time allocations (CTAs)
Isochronous streams
Asynchronous channel time
CTA in the current spec seems not perfectly adequate for real-time streaming applications
Q. Can we meet the requirement for transmission within the deadline in the case that channel status is not good?
Yoon et al., MAC enhancement considerations for multimedia streaming

5. QoS (Cont’d) Channel error
September 2003
QoS (Cont’d)
Channel error
When channel status becomes bad, the source DEV of a isochronous stream cannot transmit its pending frames within the CTA of the current superframe
Iso. stream
Async. CTA
scheduling point
(before superframe)
Allocated
error
Q. How do we know the exact amount of required channel time units a priori at the scheduling point?
But in real, 3 more
time units required for rtx
That is, the allocation should have been …
Yoon et al., MAC enhancement considerations for multimedia streaming

6. Utilization QoS vs. network utilization of VBR streams
September 2003
Utilization
QoS vs. network utilization of VBR streams
If we allocate channel time to the peak rate of a VBR stream, QoS is kept, but many of CTAs are not fully used, thereby resulting in lower utilization
If we allocate channel time to the average rate of the VBR stream, we cannot meet QoS requirements of all the VBR frames
Q. Can we transmit frames within the deadline while avoiding underutilization of channels in the case that the applications are VBR streams?
(i) Peak rate allocation
(ii) Average rate allocation
Iso. stream
Async. CTA
Iso. stream
Async. CTA
I frame
Cannot send
P frame
Not used
Not used
B frame
Yoon et al., MAC enhancement considerations for multimedia streaming

7. September 2003
Throughput
A typical service scenario in the home can be characterized by the following streams occurring simultaneously (by CableLabs)
1 Hi-Def streams (max 19.6~32 Mbps)
2 Std-Def streams (max 2*(4~14) Mbps)
2-3 Audio Streams (max 3*384 Kbps (5.1channel))
1-2 PC Streams (max 2*(2~10) Mbps)
Excess bandwidth beyond the above is desirable
So that additional streams can be accommodated as future services are rolled out
Q. MAC overhead minimization (preamble, IFS, ACK, etc.) is necessary as PHY data rates scale upward?
Yoon et al., MAC enhancement considerations for multimedia streaming

8. Piconet Formation Characteristics (goal)
September 2003
Piconet Formation
Characteristics (goal)
Ability to form ad hoc connections
Ease of joining and leaving an existing network
Connection time less than 1 sec
Q. With the current spec, is it possible to limit connection time less than 1 sec?
Beacon detection
Association process
No guarantee in time bound  contention in slotted aloha (in association MCTA) or CSMA/CA (in CAP)
Is secure membership establishment included in connection time?
Yoon et al., MAC enhancement considerations for multimedia streaming