Ultra Wide Bandwidth (UWB) MAC and Networking

Future Networking Research Topic

Ke Liu

Dec. 18, 2006

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

Why UWB? Wireless Connectivity for Digital Home

WiMedia Participants

UWB PHY and MAC standardization

180+ companies180+ companies(PC, CE, Cellular(PC, CE, Cellular

Players)Players)

WiMediaWiMediaEndorsesEndorses

MBOA PHYMBOA PHYMay 04May 04

Convergence layerfor multiple protocols

WiMedia UWB MAC protocol TDMA based Contention based (IEEE 802.11) QoS Supported (IEEE 802.11e based) Although IEEE 802.15.3 was being standar

dized, it ceased this.

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

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

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

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

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).

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

Important IEs Examples

BPOIE: Beacon Period Occupancy IE BP Switch IE: synchronizing BPSTs of neig

hbors Identification IE: addressing devices DRP IE: distributed reservation protocol IE DRP Availability IE: the DRP communicati

on MAP PCA IE: prioritized contention access IE

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 s

ending token through a mechanism as IEEE 802.11e

Data Communication Acknowledges

3 Acknowledge methods No-Ack: no acknowledge required Imm-Ack: acknowledge is required for each pa

cket received B-Ack: block acknowledge, one acknowledge i

s required for each block (block size varies) The acknowledge requirement is set throug

h packet header

DRP Throughput: simulation demo

UWB MAC Throughput

0

50

100

150

200

250

300

350

53.3 80 106.7 160 200 320 400 480Bandwidth (Mbps)

Thro

ughp

ut (

Mbps

)

No Ack (pkt 1K)Imm Ack (pkt 1K)No Ack (pkt 2K)Imm Ack (pkt 2K)No Ack (pkt 4K)Imm Ack (pkt 4K)

DRP Throughput: simulation demo (cont’)

0

50

100

150

200

250

300

53.3 80 106.7 160 200 320 400 480

No Ack (pkt 1K)Imm Ack (pkt 1K)No Ack (pkt 2K)Imm Ack (pkt 2K)No Ack (pkt 4K)Imm Ack (pkt 4K)

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