Co-Located Multi-Radio Coexistence Design Considerations

Document Number: IEEE S80216m-08/897r2Date Submitted: 2008-09-11Source: Jing Zhu, Hujun Yin, and Sassan Ahmadi

Intel Corporation

Venue: IEEE 802.16m-08/033 “Call for Contributions on Project 802.16m System Description Document (SDD)”, in response to the following topics: “Multi-Radio Coexistence”, MAC relatedBase Contribution: IEEE C80216m-08/897r2Purpose: to be discussed and adopted by TGm for the 802.16m SDD Notice:

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Voice: +1-503-2647073Email: jing.z.zhu@intel.com

2

Background (1): Multi-Radio Usages

WiMAX

Wi-Fi

BluetoothHeadset

Seamless HandoverSeamless Handover

•Mobile user terminals are rapidly evolving to devices with multiple connectivity capabilities:

–Wi-Fi*: enabling internet/intranet access and access to peripherals like cameras, etc.. –WiMAX*: WAN access to mobile Internet, cellular type applications–Bluetooth*: provides short range connectivity to headsets, etc.

*: other names and brands may be claimed as the properties of others

Wireless Peripherals

BluetoothHeadset

3

Usage Example: Wireless Peripherals

Peripheral General Mouse

Hi precision

Mouse

Keyboard Voice Quality Headset

CD Quality headphones

Aggregate Throughput

< 8kbps < 8kbps < 8kbps 256 kbps 384kbps

Latency < 10ms < 3ms < 50ms < 30ms < 100ms

Mobile Internet over IEEE 802.16m

Wireless Peripherals over IEEE 802.11 and 802.15

Base StationMobile Station

4

Background (2): Problem and Solution

• Problem: Interference between co-located radios– small separation, e.g. <20MHz between 2.4GHz and 2.3/2.5GHz– wideband interference, e.g. receiver blocking and OOB emission– little isolation, e.g. 10~30dB isolation on a small form-factor

device

• Solution 1: RF domain (filtering, isolation, etc.) – costly, large in size, highly platform dependent– not effective to wideband interference with small separation

• Solution 2: Time domain (TDM / MAC coordination)– universal, effective, and media independent – enabled by packet switching and spectrum efficient air-link– but need air-interface / scheduling support

5

802.16 Rev2 Co-Located Coexistence Support

• PSC-based Mode 1 TDM-based CLC with Wi-Fi– BS is required to honor the configurations for the PSC in the MS MOB_SLP-REQ

message, and does not gratuitously reject or modify the configuration. – MAP Relevance: defines that the listen and sleep interval follow the MAP

relevance. For example, the UL subframe of each listening and sleep interval is shifted to the next frame compared to the DL subframe of that interval according to the MAP relevance.

• PSC-based Mode 2 TDM-base CLC with Bluetooth eSCO– BS shall not provide any MS UL allocation in the first frame of the listening interval – BS should provide any DL allocation as much as possible in the first frame of

listening interval– BS shall, to all extent possible, populate the DL subframe such that DL allocations

for all MS with Co-located-Coexistence-Enabled active PSC and with allocations in the current DL subframe, precede in time the allocations for other MS that do not need co-located coexistence support and are allocated in the same DL subframe.

• UL Band AMC Reduce Interferences to Other Radios– either lowermost or uppermost frequencies will be used for UL band AMC

subchannel allocations to achieve the maximum spectrum separation between 802.16 radio and the co-located radio in the adjacent bands.

6

PSC-based Mode 1 (w/ MAP Relevance)

802.16 radio active

Preamble

FCH+MAP

MS’s DL allocations

Listening Window(1 frame)

Sleep Window (1 frame)

DL

Sleep Window (1 frame)

MS’s UL allocations

ULULDL DLUL

802.16 radio active

Preamble

FCH+MAP

MS’s DL allocations MS’s UL allocations

Sleep Window(1 frame)

Listening Window (2 frames)

DL UL DL UL DL UL

UL MAP RelevanceUL MAP Relevance““ MAP Relevance” MAP Relevance” provides balanced provides balanced DL/UL throughput DL/UL throughput with shorter duty with shorter duty cycle, which cycle, which benefits the QOS.benefits the QOS.

7

PSC-based Mode 2

802.16 radio active

Preamble

FCH+MAP

MS’s DL allocations MS’s UL allocations

Sleeping WindowListening Window

DL UL DL UL DL UL

Tx 1stRtx

2nd Rtx

Rx Rx Rx

2.06ms

Bluetooth EV3 (period=3.75ms)

Rtx: retransmissionTx: transmissionRx: receive

8

How to improve 802.16 Rev2?

• Efficiency– granularity is fixed to frame, e.g. 5ms, and has a direct impact on the

efficiency of TDM-based CLC operation, particularly when radio transmissions take less than 5ms

• Flexibility– MS determines CLC pattern, giving little flexibility for BS to adjust

according to network condition– CLC period has to be the integer number of frames, and may not

suitable to some application.

• Scalability – only one PSC is allowed active at any given time per MS, and difficult

to support multiple radios / applications.

• Compatibility – power save needs to be disabled when CLC is active

• sleeping pattern is determined by 802.16m traffic • CLC pattern is determined by co-located non 802.16m traffic

9

Design Considerations

• Type of CLC Activities – Timing Parameters– Definition– Granularity Analysis

• Impact of CLC Activities

• Multiple CLC Activities

10

Co-Located Coexistence (CLC) Activity Examples

Bluetooth SCO (HV3)

TxTx RxRx 2

625us

3.75ms

1 3 4

Wi-Fi Beacon Rx RxRx RxRx

102.4ms

varied

Wi-Fi Data Tx DataData ACKACK

varied (depends on data rate and payload)

DataData ACKACK

Flexible(constrained by latency / throughput requirement)

5 6

RxRx

102.4ms

15ms (3 frames)

Problem Description: Co-located Coexistence (CLC) Activities are the Tx or/and Rx activities of one or multiple co-located radios that are not detectable over the air, but will impact the communications to / from another co-located radio.

11

Timing Parameters

ta

tp

t0

Start Time

Active Period

Active IntervalActive Interval

Granularity

Active Period Granularity

12

Type of CLC Activities

Is the active period equal to the integer number of frames?

Yes No

Is the active pattern adjustable by Base Station?

No Type I(Bluetooth, …)

Type II(Wi-Fi Beacon, …)

Yes Type III(Wi-Fi data, …)

• 802.16 Rev2 only supports Type I • Type I, II, and III cover current co-located multi-radio

coexistence usages, and can be extended for future

13

Granularity

Beacon Transmission

Time

Wi-FiBeacon Interval (102.4ms)

CLC Period (100ms)

2.4ms 4.8ms

Drifting 2.4ms every 100ms due Drifting 2.4ms every 100ms due to unmatched granularityto unmatched granularity

802.16 Rev2 802.16m

Active Period

Type I frame (e.g. 5ms) frame (e.g. 5ms)

Type II 1us

Type III frame (e.g. 5ms)

Active Interval

Type I frame (e.g. 5ms)

subframeType II

Type III

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Impact of Active Interval Granularity

• Efficiency: the ratio of the actual radio active time to the CLC active interval

• Overhead: the number of bits to describe the length of the CLC active interval

A

A

a

A

tt

t

t

)1(log 2

At

15

Efficiency & Overhead Analysis (1): Bluetooth

EfficiencyOverhead

(5-slot)1-slot(tA=440us)

3-slot(tA=1690us)

5-slot (tA =2940us)

subframe(617us) 71% 91% 95% 3

frame (5ms) 9% 34% 59% 1

S M S M S M S M

5ms

625us

Idle Time: 185us

617us

Bluetooth Slot

802.16m subframe Idle Time: 62.86us

Slot-to-Subframe Mapping for synchronized 802.16m and

Bluetooth coexistence

16

a) 617us (subframe) b) 5ms (frame)

Efficiency & Overhead Analysis (2): IEEE 802.11g

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500

Payload

Effic

ienc

y

6Mbps9Mbps12Mbps18Mbps24Mbps36Mbps48Mbps54Mbps

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500

Payload

Effic

ienc

y

6Mbps9Mbps12Mbps18Mbps24Mbps36Mbps48Mbps54Mbps

Overhead (6Mbps, 1500 Bytes)

Subframe (617us) 3

Frame (5ms) 1

50%

Configuration: one frame per active interval, single user (no contention)

17

Impact of CLC Activities

• IEEE 802.16m mobile station (MS) co-located with other radios subject to periods of time when it is– not permitted to transmit to protect communication to co-located radio

– unable to receive due to interference by transmission from co-located radio

– unable to transmit or receive due to • shared component requiring mutually exclusive access, e.g. switched

antenna

• unknown time boundary between Tx and Rx, e.g. 802.11 data/ack

• Concurrent Tx or Rx should be supported to maximize time available for operation– Wi-Fi Beacon: only RX for STA

– Bluetooth SCO/eSCO: a slot is either Tx or Rx

• CLC and Sleep Mode should be supported independently– sleeping pattern is optimized for 802.16m traffic

– CLC pattern is optimized for non 802.16m traffic

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Multiple CLC Activities • Concurrent operation of multiple CLC classes should

be supported– MS may have multiple co-located radios, and each co-

located radio may have multiple applications with different active patterns.

– The state of MS should be the superset of all active CLC classes.

No Rx

NoTx&Rx

NoTx&Rx

NoTx

No Tx

NoTx

No Tx

NoTx&Rx

NoTx&Rx

NoTx&Rx

CLC Class A

CLC Class B

State of MS as a whole

Frame kSubframe

Frame k+1

PSC Class A

PSC Class B

State of MS as a whole

Frame

Sleeping Window

19

Recommendations

• Support Type I, II, and III CLC Activity

• Granularity of CLC Activity– active period: frame or microsecond (Type-II only)– active interval: subframe

• Consider the Impact of CLC Activity on Tx and Rx separately

• Support Multiple CLC Activities

• Support Sleep Mode and CLC Independently– sleep mode can also be used to support CLC

20

Proposal: Explicit Co-located Coexistence Control

•Static Control MS: send out MOB_CLC-REQ to report Type-I or/and Type-II CLC activities BS: respond with MOB_CLC-RSP to accept or reject the request– If “accept”, not provide MS allocation to the impacted intervals– Otherwise”, indicate the limits

•Dynamic Control MS: send out MOB_CLC-REQ to report a set of parameters for Type-III CLC activities

BS: respond with MOB_CLC-RSP to accept or reject the request– If “accept”, provide the information of CLC active intervals– Otherwise, indicate the limits BS: update the information with MOB_CLC-RSP

BS

MS

MOB_CLC-REQ

MOB_CLC-RSP

MOB_CLC-RSP (Update)

11

22 33

11

22

11

22

33

21

Proposed Text for SDDInsert the following text into Chapter 8:8.1.4 Multi-Radio Coexistence Support Protocol Structure

Fig.8 shows an example of multi-radio device with co-located IEEE 802.16m MS, IEEE 802.11 device, and IEEE 802.15.1 master. The multi-radio coexistence functional block of the IEEE 802.16m MS obtains the information about other co-located radio’s activities via inter-radio interface, which is internal to multi-radio device and out of the scope of IEEE 802.16m.

IEEE 802.16m provides protocols for the multi-radio coexistence functional blocks of MS and BS to communicate with each other via air interface. MS generates management messages to report its co-located radio activities to BS, and BS generates management messages to respond with the corresponding actions to support multi-radio coexistence operation. Furthermore, the multi-radio coexistence functional block at BS communicates with the scheduler functional block to operate properly according to the reported co-located coexistence activities.

IEEE 802.16m BS

IEEE 802.16m

MS

IEEE 802.11 STA

IEEE 802.11

STA

IEEE 802.15.1 device

IEEE 802.15.1 device

Multi-Radio Device

air interface

inter-radio interface

Fig.8 Example of Multi-Radio Device with Co-Located IEEE 802.16m MS, IEEE 802.11 STA, and IEEE 802.15.1 device

22

References

[1] IEEE 802.19-08/0021, “IEEE 802 Air-Interface Support for Co-Located Coexistence”, July 2008

[2] IEEE 802.16 Rev2/D4, April 2008

[3] IEEE 802 Tutorial on “WPAN/WLAN/WWAN Multi-Radio Coexistence”, Nov 2007

[4] WiMAX Forum, “Proposal for WiMAX-Bluetooth and WiMAX-WiFi Coexistence,” September 2007