July 2007

Zhu & Stephens (Intel Corporation)

Slide 1

doc.: IEEE 802.11-07/2117r0

Submission

WPAN/WLAN/WWAN Multi-Radio Coexistence

Date: YYYY-MM-DD

Name Company Address Phone email Jing Zhu Intel

Corporation +1 (503) 264-

7073

jing.z.zhu@intel.com

Adrian Stephens Intel Corporation

+1 (503) 616-3800

adrian.p.stephens@intel.com

Authors:

July 2007

Zhu & Stephens (Intel Corporation)

Slide 2

doc.: IEEE 802.11-07/2117r0

Submission

Abstract

This presentation gives an overview on multi-radio coexistence, covering usage model, problem, analysis, and solution. It shows that coexistence has to consider both proximity and collocation. Collocation imposes big challenges due to limited isolation and various interference sources. Today’s solutions are neither effective , nor scalable with number of radios and number of vendors. Standardization efforts are needed to provide information service, command, and air-interface support necessary for addressing coexistence issues.

July 2007

Zhu & Stephens (Intel Corporation)

Slide 3

doc.: IEEE 802.11-07/2117r0

Submission

Radios on a platform Usage Radio Band

WAN

Cellular (GSM, CDMA, GPRS)

824-894 MHz, 880 – 960 MHz

1770-1880 MHz, 1850-1990 MHz

UMTS (W-CDMA, CDMA 2000, 1XEV-DV, 1XEV-DO)

1920-1980 MHz

2110 -2170 MHz

802.16 (WiMAX) 2.300 – 2.400 GHz

2.496 – 2.690 GHz

3.300 – 3.800 GHzLAN 802.11 (WiFi) 2.412-2.4835 GHz

4.9 – 5.9 GHz

PAN 802.15.1 (Bluetooth) 2.4GHz

UWB (Wireless USB) 3.1GHz – 10.6GHz

Location GPS 1.2GHz, 1.5 to 1.6 GHz

Digital Broadcast DVB-H TV 1.6 to 1.7 GHz

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

July 2007

Zhu & Stephens (Intel Corporation)

Slide 4

doc.: IEEE 802.11-07/2117r0

Submission

Multi-Radio Coexistence Usage Scenarios • Proximity (client): two devices are in proximity, where one is connecting with WLAN,

and the other is connecting with WWAN.

• Collocation – VoIP Call + 802.15.1 (Client)

• a mobile device is making a VoIP call via WiFi or WiMax or Cellular connection and with a Bluetooth headset.

– Seamless Vertical Handover (Client)• a mobile device running network applications (VoIP, net-meeting, video streaming) is roaming

from inside (covered by WLAN) of a building to outside (covered by WWAN) with seamless vertical handover, and WLAN and WWAN radios on the device need to operate simultaneously during the handover.

– Wireless Peripheral and Internet Access (Client)• computer peripherals are going wireless, such as (wireless) USB, (BT) keyboard / mouse, and

others. A client (PC) is connecting to the world (Internet) via WiFi or WiMAX or Cellular, and the peripherals are connecting the client (PC) via UWB or Bluetooth or WiFi.

– Wireless Gateway (Infrastructure / AP) • a residential gateway that have both radios, one for in-bound (e.g. WiFi), and the other for out-

bound (e.g. WiMAX)

– Wireless Display and Internet Access (Client)• a mobile device is displaying or projecting its screen over WLAN, and in the mean time

connecting the Internet via WWAN .

July 2007

Zhu & Stephens (Intel Corporation)

Slide 5

doc.: IEEE 802.11-07/2117r0

Submission

Coexistence Problems

• Proximity – Path Loss Model

• Collocation– OOB (out-of-band) emission /

Transmitter Noise

– Receiver blocking / desensitization

– Inter-Modulation Product (IMP)

10MHz10MHz

12MHz12MHz

July 2007

Zhu & Stephens (Intel Corporation)

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doc.: IEEE 802.11-07/2117r0

Submission

Coexistence Analysis• Analysis Methods (source: IEEE 802.19-07/0003r0)

– Minimum Coupling Loss (MCL)– the worst-case approach, to establish rigid rules for minimum “separation”

– Analysis of Random Trials- the Monte-Carlo method, to establish probability of interference for a given realistic deployment scenario

• Modelling Coexistence Interference (source: IEEE 802.11-06/0338r4)

– Geometric Analysis (link budget, path loss model) path loss model is not accurate for modelling collocation interference

– Temporal / Spectral Analysis (hit probability) still apply to collocation, but need to consider adjacent band

• Other Issues– Identify / Characterize Interference Sources: OOB emission, receiver

blocking, Inter-Modulation (IM) – Evaluate Interference Rejection Measures: adaptive frequency

hopping (AFH), antenna isolation, filtering

July 2007

Zhu & Stephens (Intel Corporation)

Slide 7

doc.: IEEE 802.11-07/2117r0

Submission

TechniqueTechnique Issues Issues

Spectrum: FCC spectrum partition / spectrum mask

•insufficient in reducing interferences for proximity and collocation

•need refining for proximity coexistence

•not effective for collocation coexistence

PHY: Antenna Isolation (AI), AFH, transmission power control (TPC), dynamic frequency selection (DFS), notch filtering

• sacrifice performance (e.g. filter reduces dynamic range)

• vendor-specific, component-specific and often not interoperable

•not scalable (with number of radios)•not future compatible, slow Time-To-Market (TTM)

•additional cost and size

• not effective for severe collocation coexistence problem (e.g. MCL > 55dB)

Time Sharing (TS): Packet Traffic Arbitration (PTA), Alternating Wireless Medium Access (AWMA)

• pair-wise, not scalable to number of radios,

• limited application for proximity

• less effective without support of wireless stacks, i.e. best-effort

Overview of Coexistence Solutions

July 2007

Zhu & Stephens (Intel Corporation)

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doc.: IEEE 802.11-07/2117r0

Submission

Comments• PHY solution is not enough:

– sacrifice transceiver performance (e.g. filter reduces dynamic range)

– cost due to additional filter, and other HW

– not efficient for severe coexistence problem

• Proprietary solution does not scale: – solutions forced to be pair-wise, vendor-specific, component-specific and often

less optimal use of resources or spectrum • not scalable (with number of radios) , not future compatible, slow TTM

– example: Packet Traffic Arbitration (PTA)• widely adopted by industries

• But, PTA is limited: (1) 2 radios; (2) WiFi + BT; (3) black-box

• Coexistence issues between different wireless standards is addressed today as after-thought, and successfully addressing these issues requires standardized support in the individual standards bodies within a common framework.

Media Independent Coexistence (MICE) Service

Coexistence Aware Air-Interface

July 2007

Zhu & Stephens (Intel Corporation)

Slide 9

doc.: IEEE 802.11-07/2117r0

Submission

State of the Art in IEEE Standard • 802.15.2: WPAN/WLAN coexistence on 2.4GHz band• 802.16.2: Coexistence of Fixed Broadband Wireless Access Systems• 802.16h: Coexistence Mechanisms for License-Exempt Operation• 802.11h: Coexistence with military radar systems and medical devices

on the 5GHz band– Dynamic frequency selection (DFS) – Transmit power control (TPC)

• P1900.2: interference and coexistence analysis for ANY radio systems• 802.19: interference and coexistence analysis for 802 wireless systems

lack of standardized support for information service, commands, air-interface ... for multi-radio coexistence, and often less than optimal use of resources or spectrum!

July 2007

Zhu & Stephens (Intel Corporation)

Slide 10

doc.: IEEE 802.11-07/2117r0

Submission

Media Independent Coexistence (MICE) Service (Concept)

MICE

Protocol and Device Hardware

Applications

TCP / IP, radio management, etc.

WLAN WPAN WWAN

Information Service Coexistence Policy

Commands

July 2007

Zhu & Stephens (Intel Corporation)

Slide 11

doc.: IEEE 802.11-07/2117r0

Submission

Components of MICE Service• Network Information Service

– useful for proximity, and need protocol support

– spectrum mask or PHY solution is capable to address the proximity case• > 40dB isolation provided over the air

• Radio Information Service – time schedule (start time, end time, TX / RX)

– spectrum / energy profile (channel width, central frequency, modulation, power)

– transceiver RF profile (receiver blocking, IP3, etc.)

– … …

• Commands for Coordination – request: a radio to request for its TX / RX action

– grant: the controller to grant the radio its request

– deny: the controller to deny the request

– recommend: the controller to recommend allocation

– … …

• Coexistence Policy– priority, schedule conflict, … …

• Goal: enabling /facilitating coexistence aware air-interface

July 2007

Zhu & Stephens (Intel Corporation)

Slide 12

doc.: IEEE 802.11-07/2117r0

Submission

Example: Protecting 802.11 Downlink in the Presence of Coexistence Interference

TX TX RX

T

XY

Collision occurs if

Radio X

802.11TXOP

L

(T + L > X and T < X)or

(X < T < Y )

Timecollision

Optimal TXOP

Reduced TXOP Value

Receiver-based TXOPreduction

CFEnd

July 2007

Zhu & Stephens (Intel Corporation)

Slide 13

doc.: IEEE 802.11-07/2117r0

Submission

What is the benefit?

• More efficient usage of wireless medium and spectrum– prevent ill-guided air-interface behavior

– reduce frame loss

– seamless interaction among radios

• Lower cost of implementing coexistence solution– unified interface / signaling

– scale to number of radios and number of vendors

• Better user experience– support more multi-radio coexistence usage models

– cheaper / smaller device without sacrificing functionality & performance

July 2007

Zhu & Stephens (Intel Corporation)

Slide 14

doc.: IEEE 802.11-07/2117r0

Submission

Conclusion

• Multi-radio simultaneous operation is becoming the norm, and coexistence interference is the limiting factor– Proximity & collocation

• Existing approaches are ineffective

– lack of standard support in information service, commands, air-interface, etc. , and often less optimal use of resources or spectrum

– solutions forced to be pair-wise, vendor-specific, component-specific and NOT scale with number of radios, and number of vendors (inter-op)

• Call-for-discussion

July 2007

Zhu & Stephens (Intel Corporation)

Slide 15

doc.: IEEE 802.11-07/2117r0

Submission

References• IEEE 802.19-07/0003r0

• IEEE 802.11-06/0338r4

• IEEE P802.21 Tutorial

• M. Konrad, W. Koch, and J. Huschke, “Coexistence Analysis of Bluetooth and Cellular UMTS in the 2500-2690 MHz Band”, IEEE WCNC 2006.

• A. Waltho, “Performance Analysis and Design Considerations for Multi-Radio Platforms”, Intel Developer Forum 2006, Taipei

• S. Timiri, “RF Interference Analysis for Collocated Systems”, Microwave Journal, Jan. 1997.

• J. Zhu, A. Waltho, X. Yang, X. Guo, “Multi-Radio Coexistence: Challenges and Opportunities”, IEEE ICCCN 2007