1. Medium Congestion Control (MCC) Framework
Month Year
doc.: IEEE yy/xxxxr0
July 2006
Medium Congestion Control (MCC) Framework
Date:
Authors:
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B. Wells, DENSO LA Laboratories
John Doe, Some Company

2. July 2006
Abstract
Contribution submitted to address comments against LB #81, P802.11p D1.0.
A MAC Medium Congestion Control (MCC) framework is presented for detecting and controlling medium congestion. The framework and primitives allow an upper layer or control plane entity to manage a collection of measurements and controls via the MAC. The primary features of this framework include MAC components to measure congestion conditions and report these measurements to a client, and to influence congestion conditions based on client requests.
B. Wells, DENSO LA Laboratories

3. Problem description Addresses the following LB81 comments:
July 2006
Problem description
Addresses the following LB81 comments:
101, 928, 956, 1009, 1029, 1131, 1201, 1207, 1217, 1278.
As traffic on a communication medium increases, so does congestion and message latency. High priority management frames and safety messages must not be dropped or restricted from access to the medium. Congestion Control methods are needed to ensure high priority frames are not dropped and are delivered with minimal latency, even under heavy load conditions.
B. Wells, DENSO LA Laboratories

4. Goals Define MAC/PHY components to efficiently: Minimize frame loss,
July 2006
Goals
Define MAC/PHY components to efficiently:
Minimize frame loss,
Minimize latency, particularly for high priority frames,
Maximize channel availability,
Allow client to accurately measure congestion.
Allow client to control congestion.
B. Wells, DENSO LA Laboratories

5. Requirements Local congestion monitoring. Congestion control methods.
July 2006
Requirements
Local congestion monitoring.
Measure channel utilization.
Measure station’s contribution to congestion.
Provide measurements to client.
Congestion control methods.
Do not limit MAC/PHY performance.
Provide manual control services.
Promptly execute controls for stable feedback loop.
Allow automated control.
B. Wells, DENSO LA Laboratories

6. Client/Server Model Client (e.g. SME) Server (e.g. MLME)
July 2006
Client/Server Model
Client (e.g. SME)
Decision maker
Request measurements
Analyze measurements
Request controls
Server (e.g. MLME)
Collect direct measurements
Calculate/derive indirect measurements
Report indirect measurements
Execute controls requested by client
B. Wells, DENSO LA Laboratories

7. July 2006
Measures
Measures indicate a level of wireless medium congestion or an effect of wireless medium congestion.
Client requests measure.
Server takes direct measurements within the MAC/PHY.
Server derives indirect measurements from one or more direct measures.
Server reports derivative (indirect) measures to the Client .
B. Wells, DENSO LA Laboratories

8. Description of derivation
July 2006
Measurement Examples
Derived Measurement
Dependencies
Description of derivation
Receive Frame Rate (RX/FR)
MFP, PHY-CHAR
Rate of frames received (destined to the measuring STA) (see 11A.7).
Transmit Frame Rate (TX/FR)
Rate of frames transmitted (by the measuring STA) (see 11A.7).
Aggregate Frame Rate (Utilization) (AFR)
Rate of frames received and transmitted (including received frames destined to other STAs) (see 11A.7).
Receive Data Rate (RX/DR)
Ratio of payload received to burst rate used (destined to the measuring STA) (see 11A.7).
Transmit Data Rate (TX/DR)
Ratio of payload transmitted to burst rate used (by the measuring STA) (see 11A.7).
Aggregate Data Rate (Utilization) (ADR)
Ratio of utilization to burst rate used (including received frames destined to other STAs) (see 11A.7).
Queue Level (QL) QS
Queue size relative to maximum size (see 11A.7).
Mean Retry Count (MRC) RC
Average of retry count or frame drop rate over a predetermined or given time.
Mean Frame Drop Rate (MDR)
FDE
Fraction of frames dropped over a predetermined or given time.
Mean Contention Window Index (MCW) CW
Average of contention window index value over a predetermined or given time.
Network Activity Rate Level (NARL)
NAV, CCA
Ratio of busy time to total time period(s) considered.
Source Diversity (SD)
MFP
Number of unique MAC addresses observed over total time period(s).
B. Wells, DENSO LA Laboratories

9. July 2006
Controls
Control involves potential actions to address over-utilization or underutilization and potential reporting of action taken to an upper layer.
Basic Controls
Provide the client with manual controls.
Can also be operated by an adaptation requested by the client.
Adaptive Controls
Allow automated congestion control.
One or more controls can be applied based on the result of one or more measurements.
B. Wells, DENSO LA Laboratories

10. Control Examples July 2006 B. Wells, DENSO LA Laboratories Control
Units
CWmin
See e
CWmax
TXOP
AIFS
SuspendAC
0 (normal), 1 (suspend)
Delay
[us]
Throttle
AccessTimeConstraint
Numerator in fraction N/255 (percentage)
ShortRetryLimit
Maximum number of attempts.
LongRetryLimit
RTSThreshold
[bytes]
AlwaysBackoff
0 (normal), 1 (force backoff)
CWReversion
Number of successful transmissions before reversion.
CWIncrement
CW Index Step
SuspendChannel
(mask, 1 = enabled)
B. Wells, DENSO LA Laboratories

11. Basic Congestion Control Sequence
July 2006
Basic Congestion Control Sequence
Client
MAC/PHY
Medium
decision
Measure.Request
validate
Measure.Confirm
Observe
measure
Measure.Indicate
report
decision
Control.Request
validate
Control.Confirm
Impact
execute
B. Wells, DENSO LA Laboratories

12. July 2006
Adaptive Controls
Adaptive controls are executed by the MAC without requiring further input from a client.
A client may request an adaptation by specifying:
a derivative measure,
a control,
an adaptation (how to change the control),
a threshold (how to trigger the adaptation to the control).
B. Wells, DENSO LA Laboratories

13. Adaptive Congestion Control Sequence
July 2006
Adaptive Congestion Control Sequence
Client
MAC/PHY
Medium
AdaptConfig.Request
AdaptConfig.Confirm
validate
Adapt.Request
Adapt.Confirm
validate
Observe
measure
execute
Impact …
Observe
measure
execute
Impact
Adapt.Indicate
report
B. Wells, DENSO LA Laboratories

14. July 2006
Summary
The MAC MCC Framework allows a client residing in an upper layer or a control plane to manage medium congestion by providing derived MAC/PHY measures and providing both manual and automated controls of relevant and e MAC/PHY parameters.
This MAC MCC Framework overview and accompanying standards text is being submitted to TGp to address the following LB81 comments:
101, 928, 956, 1009, 1029, 1131, 1201, 1207, 1217, 1278.
B. Wells, DENSO LA Laboratories

15. July 2006
Motion
Move to accept the proposed MAC MCC Framework and request corresponding standards text to be drafted and submitted as TGp resolution to comments 101, 928, 956, 1009, 1029, 1131, 1201, 1207, 1217, and 1278, submitted against P802.11p D1.0 (LB81).
Moved:
Second:
Approve:
Against:
Abstain:
B. Wells, DENSO LA Laboratories

16. References FCC 03-324, US FCC Report & Order, February 2004.
July 2006
References
FCC , US FCC Report & Order, February 2004.
IEEE P802.11p/D1.0, March 2006.
IEEE P802.11s/D0.01, March 2006.
IEEE P REVma/D6.0, May 2006.
IEEE DCN , LB81 D1.0 Comment Resolutions.
B. Wells, DENSO LA Laboratories