January, 2006 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. 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. Chun-Ting Chou, Philips

Medium Access Control (MAC) in Wireless PAN using Directional Antennas January, 2006 Medium Access Control (MAC) in Wireless PAN using Directional Antennas Opportunities and challenges Chun-Ting Chou, Philips

doc.: IEEE 802.15-<doc#> <month year> doc.: IEEE 802.15-<doc#> January, 2006 Outline Background Benefits of Directional Antennas Challenges at MAC layer Issues of existing IEEE 802.15.3 MAC Conclusions Chun-Ting Chou, Philips <author>, <company>

January, 2006 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? Chun-Ting Chou, Philips

Benefits of Directional Antennas January, 2006 Benefits of Directional Antennas Chun-Ting Chou, Philips

Omni. vs. Directional Antennas January, 2006 Omni. vs. Directional Antennas Abstract model Advantages of directional antennas Higher gains, longer transmission range Directional transmission/reception: spatial reuse Tx Rx Rx Tx Chun-Ting Chou, Philips

Challenges at MAC Layer January, 2006 Challenges at MAC Layer Chun-Ting Chou, Philips

Challenge #1: Neighbor Discovery January, 2006 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 Chun-Ting Chou, Philips

Challenge #1: Neighbors Discovery (conti.) January, 2006 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 Chun-Ting Chou, Philips

Challenge #2: New Hidden-node Problems January, 2006 Challenge #2: New Hidden-node Problems The Cause: Deafness Asymmetry in Tx/Rx antenna gains Directional Transmission/Reception B A RTS CTS Rx B RTS B does not know the transmission between A and Rx Rx DATA A B Rx2 Many other Cases !! A does not know the transmission of B and vice versa Rx1 Chun-Ting Chou, Philips

Challenge #3: Spatial Reuse January, 2006 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) B A Rx2 Chun-Ting Chou, Philips

Challenge #3: Spatial Reuse (conti.) January, 2006 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 B RX2 A RX1 B Rx2 A Rx1 (a) Interference-free concurrent transmissions (b) Interfering concurrent transmissions Chun-Ting Chou, Philips

Challenge #3: Spatial Reuse (conti.) January, 2006 Challenge #3: Spatial Reuse (conti.) Use space-time scheduling in centralized networks Antenna gain/power control without control with control Receive interference from B Rx2 B A Rx1 directional-directional neighbors Concurrent directional transmission Rx2 B A Rx1 No interference Chun-Ting Chou, Philips

Issues of existing IEEE 802.15.3 MAC January, 2006 Issues of existing IEEE 802.15.3 MAC Chun-Ting Chou, Philips

Contention access period Channel time allocation period January, 2006 Existing IEEE 15.3 MAC Omni-omni neighbor is assumed Contention- and polling-based channel mechanism are both used Superframe # m-1 Superframe # m Superframe # m+1 Beacon # m Contention access period Channel time allocation period … MCTA 1 MCTA 2 CTA 1 CTA 2 CTA n Piconet controller/devices association via broadcasting beacons (neighbor discovery) CSMA/CA medium access control to send control messages) Scheduled transmission in channel time allocated by piconet controller Challenge # 1 Challenge # 2 Challenges # 2 and 3 Chun-Ting Chou, Philips

Conclusions Directional antennas bring in new opportunities January, 2006 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? Chun-Ting Chou, Philips

January, 2006 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 Chun-Ting Chou, Philips