1. doc.: IEEE 802.11-07/2117r0 Submission July 2007 Zhu & Stephens (Intel Corporation)Slide 1 WPAN/WLAN/WWAN Multi-Radio Coexistence Date: YYYY-MM-DD Authors:

2. doc.: IEEE 802.11-07/2117r0 Submission July 2007 Zhu & Stephens (Intel Corporation)Slide 2 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.

3. doc.: IEEE 802.11-07/2117r0 Submission July 2007 Zhu & Stephens (Intel Corporation)Slide 3 Radios on a platform UsageRadioBand 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 GHz LAN802.11 (WiFi)2.412-2.4835 GHz 4.9 – 5.9 GHz PAN802.15.1 (Bluetooth)2.4GHz UWB (Wireless USB)3.1GHz – 10.6GHz LocationGPS1.2GHz, 1.5 to 1.6 GHz Digital BroadcastDVB-H TV1.6 to 1.7 GHz other names and brands may be claimed as the properties of others

4. doc.: IEEE 802.11-07/2117r0 Submission July 2007 Zhu & Stephens (Intel Corporation)Slide 4 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.

5. doc.: IEEE 802.11-07/2117r0 Submission July 2007 Zhu & Stephens (Intel Corporation)Slide 5 Coexistence Problems Proximity –Path Loss Model Collocation –OOB (out-of-band) emission / Transmitter Noise –Receiver blocking / desensitization –Inter-Modulation Product (IMP) 10MHz 12MHz

6. doc.: IEEE 802.11-07/2117r0 Submission July 2007 Zhu & Stephens (Intel Corporation)Slide 6 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

7. doc.: IEEE 802.11-07/2117r0 Submission July 2007 Zhu & Stephens (Intel Corporation)Slide 7 TechniqueIssues 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

8. doc.: IEEE 802.11-07/2117r0 Submission July 2007 Zhu & Stephens (Intel Corporation)Slide 8 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

9. doc.: IEEE 802.11-07/2117r0 Submission July 2007 Zhu & Stephens (Intel Corporation)Slide 9 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!

10. doc.: IEEE 802.11-07/2117r0 Submission July 2007 Zhu & Stephens (Intel Corporation)Slide 10 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

11. doc.: IEEE 802.11-07/2117r0 Submission July 2007 Zhu & Stephens (Intel Corporation)Slide 11 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

12. doc.: IEEE 802.11-07/2117r0 Submission July 2007 Zhu & Stephens (Intel Corporation)Slide 12 Example: Protecting 802.11 Downlink in the Presence of Coexistence Interference Reduced TXOP Value Receiver-based TXOP reduction CF End

13. doc.: IEEE 802.11-07/2117r0 Submission July 2007 Zhu & Stephens (Intel Corporation)Slide 13 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

14. doc.: IEEE 802.11-07/2117r0 Submission July 2007 Zhu & Stephens (Intel Corporation)Slide 14 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

15. doc.: IEEE 802.11-07/2117r0 Submission July 2007 Zhu & Stephens (Intel Corporation)Slide 15 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