Ultra Wide Bandwidth (UWB) MAC and Networking

1. Ultra Wide Bandwidth (UWB) MAC and Networking Future Networking Research Topic Ke Liu Dec. 18, 2006

2. Outlines • The Background • The Architecture • Introduction to the UWB MAC protocol • Brief introduction to UWB WiNet

3. Why UWB? • Wireless Connectivity for Digital Home

4. WiMedia Participants 180+ companies (PC, CE, Cellular Players) Convergence layer for multiple protocols WiMedia Endorses MBOA PHY May 04 UWB PHY and MAC standardization

5. WiMedia UWB MAC protocol • TDMA based • Contention based (IEEE 802.11) • QoS Supported (IEEE 802.11e based) • Although IEEE 802.15.3 was being standardized, it ceased this.

6. Basic Communication Model • Superframe: the basic timing structure for fame exchange • One Superframe is composed of 256 media access slots (MASs) • Each Superframe starts with a Beacon Period (BP), decided by the number of devices involved • The start of BP (or Superframe) is called BPST (BP start time), all devices need to synchronize BPST with each other

7. Superframe Structure • In BP, each MAS consists of 3 Beacon Slots • 1 Superframe = 65,536 µs = 256 MASs • 1 MAS = 256 µs = 3 Beacon Slots • 1 Beacon slots = 85 µs

8. Communication Negotiation • The maximum size of BP consists of 96 Beacon slots • Up to 94 Devices are allowed in “Some” Range • Each involved device occupies one Beacon slot to negotiate with other devices • Except the first 2 beacon slots can be occupied by some device

9. Communication Negotiation (cont’) • A device starts up with scanning all channels (128 candidates) • On receiving a beacon in some channel, the device would select it; • After scanning several (typically 3) superframes, it would synchronize its BPST to the hearing ones. • If no beacon received on any channel, it would start a BP with a BPST decided by itself

10. Communication Negotiation (cont’) • If a beacon slot is unoccupied, the device would occupy it to send its own beacon; • If no beacon slot is available, it would send its beacon in one of the first 2 beacon slots (signal slots), and the one after the last occupied beacon slot • Other devices hear this signal slot beacon, would extend their BP length by a pre-set value (typically 3-6).

11. Communication Negotiation (cont’) • For a given device, an unoccupied beacon slot means • Beacon received through the beacon slot; • Or, beacon received by some neighbor • All the information of devices need to be exchange through Information Elements (IEs) along with beacon exchanging

12. Important IEs Examples • BPOIE: Beacon Period Occupancy IE • BP Switch IE: synchronizing BPSTs of neighbors • Identification IE: addressing devices • DRP IE: distributed reservation protocol IE • DRP Availability IE: the DRP communication MAP • PCA IE: prioritized contention access IE

13. Data Communication: DRP and PCA • Distributed Reservation Protocol (DRP): • Device reserves several MASs for sending data through DRP IE • If no conflict, other devices would reply through DRP availability IE with reserved MASs updated, • Device sends data at least one superframe later after it sends request • Prioritized Contention Access (PCA): • For any MASs un-reserved, any device can obtain the sending token through a mechanism as IEEE 802.11e

14. Data Communication Acknowledges • 3 Acknowledge methods • No-Ack: no acknowledge required • Imm-Ack: acknowledge is required for each packet received • B-Ack: block acknowledge, one acknowledge is required for each block (block size varies) • The acknowledge requirement is set through packet header

15. DRP Throughput: simulation demo

16. DRP Throughput: simulation demo (cont’)

17. Primary References Web Links • WiMedia Alliance: http://www.wimedia.org