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

2. November 2006
Abstract
A MAC Medium Congestion Control (MCC) framework is presented for locally 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.
DENSO LA Laboratories

3. November 2006
Problem description
Existing primitives such as MLME-MEASURE and MLME-MREQUEST are useful for remote (AP) channel measurement associated with channel switching or channel selection for spectrum sharing in an Infrastructure BSS. Additional primitives are needed to locally manage congestion for QoS in an IBSS and allow real-time manipulation of local MAC/PHY parameters effecting medium congestion control.
DENSO LA Laboratories

4. Goals Define MAC/PHY components to efficiently:
November 2006
Goals
Define MAC/PHY components to efficiently:
Enable local congestion control without OTA messaging.
Minimize frame loss,
Minimize latency, particularly for high priority frames,
Maximize channel availability,
Allow client to accurately measure congestion.
Allow client to appropriately control congestion.
DENSO LA Laboratories

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

6. Client/Server Model Client (e.g. SME) Server (e.g. MLME)
November 2006
Client/Server Model
Client (e.g. SME)
Decision maker
Request measurements
Analyze measurements
Request controls
Server (e.g. MLME)
Perform MAC/PHY measurements
Calculate/derive MCC measurements
Report MCC measurements
Execute controls requested by client
DENSO LA Laboratories

7. Congestion Monitoring
November 2006
Congestion Monitoring
Measurement values indicate a level of wireless medium congestion or an effect of wireless medium congestion on a specific channel.
Client may request a one-time Measurement or periodic Measurements and Reports.
Measure Requests may be cancelled or changed by the Client.
Client requests a measurement on a specific channel.
Server collects MAC/PHY measurements.
Server derives MCC measurements from one or more MAC/PHY measures.
Server reports requested measures to the Client.
DENSO LA Laboratories

8. Example MAC/PHY Measures
November 2006
Example MAC/PHY Measures
Name
Layer
Type
Focus
Clear Channel Acquisition (CCA)
PHY
Fast
Per channel
Network Activity Vector (NAV)
MAC
Contention Window (CW) Index
Slow
Per channel, AC.
Queue size (QS)
MAC/UL
Receive or Transmit a MAC Frame (RX/TX)
Per channel, AC, frame.
Retry count (RC), Frame drop count (DC)
DENSO LA Laboratories

9. MCC Measurement Examples
November 2006
MCC Measurement Examples
Derived Measurement
Dependencies
Description of derivation
Aggregate Frame Rate (Utilization) (AFR)
RX/TX, PHY-CHAR
Rate of frames received and transmitted (including received frames destined to other STAs).
Aggregate Data Rate (Utilization) (ADR)
Ratio of utilization to burst rate used (including received frames destined to other STAs).
Queue Level (QL) QS
Queue size relative to maximum size.
Mean Retry Count (MRC) RC
Average of retry count or frame drop rate 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)
RX/TX
Number of unique MAC addresses observed over total time period(s).
DENSO LA Laboratories

10. November 2006
Controls
Control involves potential actions to address over-utilization or underutilization on a particular channel, and potential reporting of action taken to an upper layer.
Control requests may be cancelled or changed by the Client.
Basic Controls
Active Control by Client
Allow the client to manually manipulate controls.
Adaptive Controls
Passive Control, once set up by Client
Allow the client to configure automated congestion detection and control by the MAC.
One or more controls can be applied based on the result of one or more measurements.
DENSO LA Laboratories

11. Control Examples November 2006 Control Units CWmin See 802.11e CWmax
AIFS
SuspendAC
0 (normal), 1 (suspend)
Delay
[us]
Throttle
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)
DENSO LA Laboratories

12. Basic Control (Active Client Control)
November 2006
Basic Control (Active Client Control)
SME
MLME
Measurement
Policy
MCC
Measurement
Measurement
Control
Decision
Control
Parameter
Management
DCF
Control
DENSO LA Laboratories

13. Basic Congestion Control Sequence
November 2006
Basic Congestion Control Sequence
Client
MAC/PHY
Medium
decision
Request (Measure)
validate
Confirm
Observe
measure
Indicate (Measure)
report
decision
Request (Control)
validate
Confirm
Impact
execute
DENSO LA Laboratories

14. November 2006
Adaptive Controls
Adaptive controls are executed by the MAC without requiring further input from a client.
A client may request an adaptation on a specific channel by specifying a Measure Control Pair including:
The Measure to monitor, (e.g., Aggregate Frame Rate)
The Condition and Threshold to compare against, (e.g., exceeds 100 Frames/second)
The Adjustment, Control, and Value to adjust, (e.g., increase CWMin by 2x)
How often to repeat the adaptation, (e.g., repeat every 50ms).
DENSO LA Laboratories

15. Adaptive Control (Passive Client Control)
November 2006
Adaptive Control (Passive Client Control)
SME
MLME
Control
Parameter
Management
Measurement
Policy
Adaptation
Policy
Adaptation
Decision
DCF
Measure & Control
Control
Policy
MCC
Measurement
DENSO LA Laboratories

16. Adaptive Congestion Control Sequence
November 2006
Adaptive Congestion Control Sequence
Client
MAC/PHY
Medium
Request Control
Confirm
validate
Observe
measure
execute
Impact …
Observe
measure
execute
Impact
Indicate Control
report
DENSO LA Laboratories

17. November 2006
Summary
The MAC MCC Framework allows a client residing in an upper layer or a control plane to effect a congestion control policy.
Normative text describing the MCC Framework has been drafted (see /1706r0).
DENSO LA Laboratories

18. November 2006
Straw Poll
Is the proposed MCC Framework appropriate and relevant to TGv?
Yes:
No:
DENSO LA Laboratories

19. November 2006
Straw Poll
Should TGv include appropriate normative text describing the MCC Framework in the TGv draft?
Yes:
No:
DENSO LA Laboratories

20. November 2006
Straw Poll
Should TGv include the text in /1706r0 be used as a baseline for text to be included in the TGv draft?
Yes:
No:
DENSO LA Laboratories