1. IEEE 802.21 MEDIA INDEPENDENT HANDOVER
DCN: MRPM
Title: Different modes of operation
Date Submitted: July, 2008
Presented at IEEE July at Denver
Authors or Source(s):
  H Anthony Chan (Huawei)
Abstract: The modes of operation defined in different networks are different and are not consistent in naming them. A useful classification is according to the response time of these modes.

2. IEEE 802.21 presentation release statements
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3. 802.21 Modes of operation: Tradeoff between power saving and response time

4. Background
DCN: MRPM attempts to explain the different power saving modes, realizing the inconsistency in naming the different modes for different networks.
DCN: MRPM addresses the need to better understand and define the possible modes along with the meaning behind.
DCN: MRPM describes the definitions of different modes in each of the different networks: , , 3GPP, and 3GPP2.
DCN: MRPM attempts to categorize the different modes (in addition to explaining many other things).

5. Power saving versus application requirements
There are tradeoffs between power-saving and operational capabilities.
The operations involved include:
Handover
Response to paging
Location update, etc.
The capability to perform each operation while optimizing power saving depends on
Application requirements
Capabilities of MN
Capabilities of Network

6. Application time scale
The needed operations (Call continuity, Handover, Response to paging, Location update, etc.) place QoS requirements according to the applications, which may be broadly categorized into
Conversational
Interactive
Streaming
Background
A relevant QoS requirements here lies in the time scale.
The QoS requirement against packet loss may also transform to time constraint during active data transfer.
>10s
Background
10s
Streaming
Record (interactive) 1s
Play back (interactive)
Delay in voice, video (conversational)
100ms
Lip synchronization
10ms
1ms
Jitter in voice and video

7. Response times handover paging Conversational Interactive Streaming
Background
Ongoing call with active data transfer (against packet loss)
~20 – 200 ms
Ongoing call not actively transferring data
~100 – 400 ms
~1 – 2 s
New call
~2 s
>2 s
< 10 s
> 10 s
handover
paging

8. time scale
The interval of beacon frame, which contains traffic indication map (TIM), is typically 100 ms
Power saving mode listens to every Delivery traffic indication message (DTIM), which are sent from AP.
The DTIM period is number of TIM intervals. Typically 1 DTIM may be several TIM intervals.
Sleep is extended power saving mode without GTK update. The sleep interval is up to 255 (1 octet) times of DTIM interval.
Use of a large sleep interval corresponds to deep sleep.

9. time scale
In active mode, need RTS/CTS in CSMA/CA before sending. Response time depends on traffic and QoS class.
In power-saving (PS) mode, response time is several beacon intervals: fraction of a second.
In sleep mode (extended PS mode), may adjust DTIM period, but no GTK update.
Location and BSS change: during wake at the designated DTIM
>10s
Deep sleep
10s
Sleep mode 1s
PS mode
DTIM interval
100ms
Beacon interval
CSMA (Active mode)
10ms
1ms