Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)

14 November, 2001

James P. K. Gilb, Mobilian

doc.: IEEE 802.15-01/508r1

Submission

Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)

Submission Title: [Overview of Draft Standard 802.15.3]Date Submitted: [14 November 2001]Source: [James P. K. Gilb] Company: [Mobilian]Address: [12707 High Bluff Dr., Suite 335, San Diego, CA, 92130]Voice:[1-858-436-2201], FAX: [1-858-436-2301], E-Mail:[[email protected]]

Re: []

Abstract: [Liaison report to the 802.15 WG on the status of the 802.11g TG.]

Purpose: [To report the status of the 802.11g TG to the 802.15 WG..]

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.

14 November, 2001


doc.: IEEE 802.15-01/508r1

Submission

Environment and Applications

14 November, 2001


doc.: IEEE 802.15-01/508r1

Submission

Environment

• Relatively short range– Required coverage is > 10 m

• Dynamic environment– Mobile devices, enter and exit piconet often– Low speed (< 7 kph)

• Personal/home environment– User controls all devices in the WPAN– Low delay spread (< 25 ns)

14 November, 2001


doc.: IEEE 802.15-01/508r1

Submission

Sample Applications

• Multimedia– Streaming audio and video– Interactive audio and video

• Data– PDAs, PCs, printers– Projectors

• Digital imaging– Still image and video– Camera to kiosk

14 November, 2001


doc.: IEEE 802.15-01/508r1

Submission

Requirements

• Range > 10 m• Data rate > 20 Mb/s• QoS capable• Security for Ad Hoc Networks• Quick join/unjoin• Basic security/authentication• Low power, cost, size, complexity• Piconet, not network connectivity

14 November, 2001


doc.: IEEE 802.15-01/508r1

Submission

MAC Characteristics

14 November, 2001


doc.: IEEE 802.15-01/508r1

Submission

Qualities of the 802.15.3 MAC

• Coordinator (PNC) – Device (DEV) topology– PNC assigns time for connections– Commands go to and come from the PNC.

• Communication is peer-to-peer• Quality of Service

– TDMA architecture with guaranteed time slots (GTSs)

• Security and Authentication

14 November, 2001


doc.: IEEE 802.15-01/508r1

Submission

Basic structure is the superframe

3 parts to the superframe• Beacon• Contention Access Period (CAP)• Contention Free Period (CFP)

• CFP has GTSs and MTSs

14 November, 2001


doc.: IEEE 802.15-01/508r1

Submission

Access methods

• Beacon– TDMA, only sent by the PNC

• CAP– CSMA/CA, types of data and commands can be

restricted by PNC– PNC can replace the CAP with management time

slots (MTSs) using slotted-aloha access.

• CFP– TDMA, assigned by the PNC– GTSs are unidirectional

14 November, 2001


doc.: IEEE 802.15-01/508r1

Submission

PNC selection/handover

• Alternate coordinators (ACs) broadcast capabilities

• Based on criteria, “best” AC is chosen and becomes the PNC

• PNC begins to issue beacon• PNC hands over task if more “capable” AC

joins the piconet– Exception only if security policy is verified

14 November, 2001


doc.: IEEE 802.15-01/508r1

Submission

Joining/transferring data

• DEV joins with association command• PNC allows based on resources• DEV authenticates (if required)• DEV can either

– Send data in CAP (if allowed)– Request GTS for specific connection

• GTSs may be either – Stream data: connection has QoS requirements– Non-stream: connection has no QoS requirements

14 November, 2001


doc.: IEEE 802.15-01/508r1

Submission

Types of GTS

• GTS may have different persistence– Dynamic GTS: position in superframe may change

from superframe to superframe– Pseudo-static GTS: PNC may change position, but

needs to communicate and confirm with both DEVs

• MTS– Used for PNC/DEV communication– May be used to substitute for CAP

14 November, 2001


doc.: IEEE 802.15-01/508r1

Submission

4 ACK policies supported

1. No ACK– Useful for streaming content

2. Immediate ACK (Imm-ACK)– ACKs immediately follow the packet

3. Delayed ACK (Del-ACK)– ACK multiple packets in one ACK command

4. Implied ACK– ACK is implied by a data frame returned in

reverse direction with ACK policy = implied-ACK

14 November, 2001


doc.: IEEE 802.15-01/508r1

Submission

4 Frame types

• Beacon - PNC uses to synchronize piconet• Immediate ACK• Commands

– Multiple commands may be in one frame– Commands and information elements are TLV (a

TLA for Type, Length and Value)

• Data– May contain encryption information.

14 November, 2001


doc.: IEEE 802.15-01/508r1

Submission

Commands

Commands support:– PNC selection and handover– Association and disassociation– Information request commands– Repeater service– Power management commands– Device information– Retransmission– Request and modify GTS allocations

14 November, 2001


doc.: IEEE 802.15-01/508r1

Submission

MAC support

• Peer Discovery• Multirate support• Repeater service• Dynamic channel selection• Power management• Transmit power control

14 November, 2001


doc.: IEEE 802.15-01/508r1

Submission

PHY Characteristics

14 November, 2001


doc.: IEEE 802.15-01/508r1

Submission

General characteristics

• 2.4 GHz band– Unlicensed operation– 15 MHz RF bandwidth– 3 or 4 non-overlapping channels– Similar to 802.11 for coexistence

• 5 data rates– 11 Mbaud– 11-55 Mb/s with multi-bit symbols and coding– Use Trellis Coded Modulation (TCM) for coding

14 November, 2001


doc.: IEEE 802.15-01/508r1

Submission

Modulation, rates and sensitivity

Modulation Coding Data rate Sensitivity

QPSK 8 state TCM 11 Mb/s -82 dBm

DQPSk None 22 Mb/s -75 dBm

16-QAM 8 state TCM 33 Mb/s -74 dBm



TCM was originally used in phone modems, many publications > 20 years old.

14 November, 2001


doc.: IEEE 802.15-01/508r1

Submission

Receiver characteristics

Defined in draft• Minimum sensitivities and maximum signal• Adjacent and alternate channel blocking• RSSI, CCA and Link Quality Indication (LQI)

Implementation dependent• Intermodulation performance• Equalization

14 November, 2001


doc.: IEEE 802.15-01/508r1

Submission

Transmitter specifications

• TX power– Up to 100 mW in EC– Up to 125 mW with FCC NPRM– 10 mW in Japan

• Transmit power control– If over +4 dBm, will control to less than +4 dBm in

monotonic steps of 3 to 5 dB

• EVM & spectral mask define signal quality– Baseband TX filter undefined

14 November, 2001


doc.: IEEE 802.15-01/508r1

Submission

Miscellaneous PHY items

• Frequency & timing derived from same clock– Should simplify RX modem implementation

• CAZAC sequence for preamble– Optimum for equalization, timing and frequency

recovery [1]

• Equalization or diversity supported for delay spread mitigation

[1] A. Milewski, “Periodic Sequences with Optimal Properties for Channel Estimation and Fast Start-Up Equalization,” IBM Journal of Research and Development, vol. 27, no. 5, pp. 426-431, September 1983.

Documents

Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)