1. doc.: IEEE 802.15-15-06-0018-00-003c Submission January, 2006 Chun-Ting Chou, PhilipsSlide 1 NOTE: Update all red fields replacing with your information; they are required. This is a manual update in appropriate fields. All Blue fields are informational and are to be deleted. Black stays. After updating delete this box/paragraph. Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [Medium Access Control (MAC) in Wireless PAN using Directional Antennas] Date Submitted: [16 January, 2006] Source: [Chun-Ting Chou, Alireza Seyedi and Richard Chen] Company [Philips] Address [345 Scarborough Rd, Briarcliff Manor, NY 10510] Voice:[914 945 6099], FAX: [914 945 6330], E-Mail:[chun-ting.chou@philips.com] Re: [N/A] Abstract:[Investigation of required MAC functionalities, given the introduction of directional antennas in 802.15.3c physical layer] Purpose:[Discuss required MAC functionalities, given the introduction of directional antennas in 802.15.3c physical layer] Notice:This document has been prepared to assist the IEEE P802.15. It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein. Release:The contributor acknowledges and accepts that this contribution becomes the property of IEEE and may be made publicly available by P802.15.

2. doc.: IEEE 802.15-15-06-0018-00-003c Submission January, 2006 Chun-Ting Chou, PhilipsSlide 2 Medium Access Control (MAC) in Wireless PAN using Directional Antennas Opportunities and challenges

3. doc.: IEEE 802.15-15-06-0018-00-003c Submission January, 2006 Chun-Ting Chou, PhilipsSlide 3 Outline Background Benefits of Directional Antennas Challenges at MAC layer Issues of existing IEEE 802.15.3 MAC Conclusions

4. doc.: IEEE 802.15-15-06-0018-00-003c Submission January, 2006 Chun-Ting Chou, PhilipsSlide 4 Background IEEE 802.15.3c Task Group is generating a high rate mm wave (60GHz) alternate PHY for 802.15.3. High frequency results in high path-loss. Hence, exploiting antenna gain is necessary. High frequency enables us to design small directional antennas and/or antenna arrays. –What functionalities are necessary and/or beneficial for a WPAN MAC with directional antennas. –Is 802.15.3 MAC equipped to handle devices with directional antennas?

5. doc.: IEEE 802.15-15-06-0018-00-003c Submission January, 2006 Chun-Ting Chou, PhilipsSlide 5 Benefits of Directional Antennas

6. doc.: IEEE 802.15-15-06-0018-00-003c Submission January, 2006 Chun-Ting Chou, PhilipsSlide 6 Abstract model Advantages of directional antennas –Higher gains, longer transmission range –Directional transmission/reception: spatial reuse Omni. vs. Directional Antennas Tx Rx Tx Rx

7. doc.: IEEE 802.15-15-06-0018-00-003c Submission January, 2006 Chun-Ting Chou, PhilipsSlide 7 Challenges at MAC Layer

8. doc.: IEEE 802.15-15-06-0018-00-003c Submission January, 2006 Chun-Ting Chou, PhilipsSlide 8 Challenge #1: Neighbor Discovery Different Tx/Rx antenna modes could be used at PHY layer Three types of neighbors –Omni-omni neighbors –Directional-omni neighbors –Directional-directional neighbors

9. doc.: IEEE 802.15-15-06-0018-00-003c Submission January, 2006 Chun-Ting Chou, PhilipsSlide 9 Challenge #1: Neighbors Discovery (conti.) Mechanisms for neighbor discovery –Discovery of omni-omni neighbors is trivial –New mechanisms are required for discovery of directional-omni and directional-directional neighbors Location/direction information makes it a lot easier; otherwise, Intelligent algorithms are needed

10. doc.: IEEE 802.15-15-06-0018-00-003c Submission January, 2006 Chun-Ting Chou, PhilipsSlide 10 Challenge #2: New Hidden-node Problems The Cause: Deafness –Asymmetry in Tx/Rx antenna gains –Directional Transmission/Reception CTS RTS DATA RTS A B A does not know the transmission of B and vice versa A B does not know the transmission between A and Rx Rx Rx1 Rx2 B B Many other Cases !!

11. doc.: IEEE 802.15-15-06-0018-00-003c Submission January, 2006 Chun-Ting Chou, PhilipsSlide 11 Challenge #3: Spatial Reuse A by-product of directional transmission and reception Advantages: higher spectrum efficiency and user/system throughput ( as high as 800% depending on the node density, antenna gain and types [1]-[3], very useful for compensating higher overheard due to high transmission rate) A B Rx2

12. doc.: IEEE 802.15-15-06-0018-00-003c Submission January, 2006 Chun-Ting Chou, PhilipsSlide 12 Challenge #3: Spatial Reuse (conti.) A non-trivial problem –Hidden node problems (challenge #2) –Longer interference range Potential Solutions –Use directional network allocation vector (D-NAV) in distributed networks Rx2 ARX1BRX2 B ARx1 (a) Interference-free concurrent transmissions (b) Interfering concurrent transmissions

13. doc.: IEEE 802.15-15-06-0018-00-003c Submission January, 2006 Chun-Ting Chou, PhilipsSlide 13 Challenge #3: Spatial Reuse (conti.) –Use space-time scheduling in centralized networks –Antenna gain/power control without control with control Rx2 B Rx1 A directional-directional neighbors Rx2 B Rx1 A No interference Receive interference from B Concurrent directional transmission

14. doc.: IEEE 802.15-15-06-0018-00-003c Submission January, 2006 Chun-Ting Chou, PhilipsSlide 14 Issues of existing IEEE 802.15.3 MAC

15. doc.: IEEE 802.15-15-06-0018-00-003c Submission January, 2006 Chun-Ting Chou, PhilipsSlide 15 Existing IEEE 15.3 MAC Omni-omni neighbor is assumed Contention- and polling-based channel mechanism are both used Superframe # m-1Superframe # m+1 Channel time allocation periodBeacon # m Contention access period MCTA 1MCTA 2CTA 1CTA 2CTA n Superframe # m … Piconet controller/devices association via broadcasting beacons (neighbor discovery) CSMA/CA medium access Control for control messages) Scheduled transmission in channel time allocated by piconet controller Challenge # 1Challenge # 2 Challenges # 2 and 3

16. doc.: IEEE 802.15-15-06-0018-00-003c Submission January, 2006 Chun-Ting Chou, PhilipsSlide 16 Conclusions Directional antennas bring in new opportunities –Longer transmission range, higher spectrum efficiency Challenges at MAC layer –Neighbor discovery, new hidden node problems, spatial reuse and power control The next step?

17. doc.: IEEE 802.15-15-06-0018-00-003c Submission January, 2006 Chun-Ting Chou, PhilipsSlide 17 References [1] R. Ramanathan and etc., “Ad Hoc Networking With Directional Antennas: A Complete System Solution,” IEEE Journal on Selected Areas in Communications, vol. 23, No. 3, Mar. 2005. [2] R. Ramanathan, “On the Performance of Ad Hoc Networks with Beamforming Antennas”, ACM MobiHoc, 2001. [3] R. Choudhury and etc., “Using Directional Antennas for Medium Access Control in Ad Hoc Networks,” ACM MOBICOM, 2002. [4] L. Bao and etc., “Transmission Scheduling in Ad Hoc Networks with Directional Antennas,” ACM MOBICOM, 2002. [5] T. Korakis and etc., “A MAC Protocol for Full Exploitation of Directional Antennas in Ad Hoc Wireless Networks,” ACM MobiHoc, 2003