Doc.: IEEE 802.15-09-0480-00-004g Power and Spectrum Efficient PHY Proposal for 802.15.4g July 2009...

July 2009

Khanh Tuan Le (TI)Slide 1

doc.: IEEE 802.15-09-0480-00-004g

Power and Spectrum Efficient PHY Proposal for 802.15.4g

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: [Power and Spectrum Efficient PHY Proposal for 802.15.4g]Date Submitted: [ 07 July, 2009]Source: [Khanh Tuan Le] Company [Texas Instruments]

[Per Torstein Roine] Company [Texas Instruments]Address [Gaustadalleen 21, 0349 Oslo, Norway] Voice: [+47 22958535], E-Mail:[[email protected]]

Re: []

Abstract: [Power and spectrum efficient PHY proposal based on GFSK for 802.15.4g. Definition of multiple channels to support FHSS and Adaptive Frequency Agility.]

Purpose: [Technical proposal. Presented to the 802.15.4g SUN Task Group for consideration.]

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.

July 2009


doc.: IEEE 802.15-09-0480-00-004g


Power and Spectrum EfficientPHY Proposal for 802.15.4g

IEEE 802 Plenary Meeting14th July 2009, San Francisco

Khanh Tuan Le

July 2009


doc.: IEEE 802.15-09-0480-00-004g


Introduction

• Efficient working technology with focus on the user

requirements, available frequency spectrum and

applicable regulations for systems operating in the

license exempt frequency bands

• This is an update of the submitted final proposal

IEEE 802.15-09-0290-02-004g “Power and Spectrum

Efficient PHY Proposal for 802.15.4g”

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doc.: IEEE 802.15-09-0480-00-004g


Proposal Update Details

• Regional ISM Bands: US, Europe and China

• Channelization

• Modulation Format and Data Rates

• Forward Error Correction (FEC)

• Data Whitening

• Packet Format

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• Focus on low system power consumption– Low power reception and listening– High transmit power efficiency

• Battery operation possible- Low average and peak current• Spectral (and spectrum) efficiency increasingly more important • Larger and more advanced networks require higher (peak) and

scalable data rates• Proven technology

– Reliable networks using FSK and GFSK today

• Multi channel support• Semiconductor technology requirements

– Power optimized and cost efficient system solutions– Flexibility

Background

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doc.: IEEE 802.15-09-0480-00-004g


• Gaussian shaping improves spectral efficiency• Constant amplitude modulation

– Use of power efficient transmitter architectures and circuitry

• GFSK can be efficiently implemented on silicon radios• Proven and widely used technology

• 2-GFSK (1 bit/symbol) / 4-GFSK (2 bit/symbol)

Gaussian Frequency Shift Keying (GFSK)

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doc.: IEEE 802.15-09-0480-00-004g


863-870 MHz ISM Band in Europe (1)

ERC/REC 70-03 (Feb-2009)

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• Frequency Band: 863-870 MHz

• Frequency sub-bands and allowed max output power:– 868.00-868.60 MHz (600 kHz): 25 mW / +14 dBm (g1)

– 868.70-869.20 MHz (500 kHz): 25 mW / +14 dBm (g2)

– 869.40-869.65 MHz (250 kHz): 500 mW / +27 dBm (g3)

• Sub-band channel spacing: 250 kHz

• Number of channels: 5

• Channel center frequencies:– 868.175 MHz and 868.425 MHz

– 868.825 MHz and 869.075 MHz

– 869.525 MHz

• Adaptive Frequency Agility (AFA) with Listen-Before-Talk (LBT)


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doc.: IEEE 802.15-09-0480-00-004g


• The center frequency of these channels is defined

as follows:

– Fc = 868.175 + 0.25 k in megahertz, for k = 0,1

– Fc = 868.325 + 0.25 k in megahertz, for k = 2,3

– Fc = 869.525 in megahertz, for k = 4

where k is the channel number


July 2009


doc.: IEEE 802.15-09-0480-00-004g


25 mW / +14 dBmMax 1% or LBT

25 mW / +14 dBmMax 0.1% or LBT

500 mW / +27 dBmMax 10% or LBT

Channel Plan Illustration

Center Freq Max Output Power

868.175 MHz 25 mW (+14 dBm)

868.425 MHz 25 mW (+14 dBm)

868.825 MHz 25 mW (+14 dBm)

869.075 MHz 25 mW (+14 dBm)

869.525 MHz 500 mW (+27 dBm)


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• Modulation format:– 2-GFSK and 4-GFSK, BT=0.5

• Data rates:– (R1) 50 kbps : 2-GFSK, modulation index 0.9

– (R2) 100 kbps: 2-GFSK, modulation index 0.9



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doc.: IEEE 802.15-09-0480-00-004g


RX Parameter Value Conditions

Receiver Category 2 ETSI EN 300 220-1 V2.3.1 (2009-04 Draft)

Receiver sensitivity

(R1) 50 kbps

(R2) 100 kbps

(R3) 200 kbps

-95 dBm

-92 dBm

-85 dBm

PER=1%, 20 bytes packet length

Selectivity

Adjacent Channel Rejetion

Alternate Channel Rejetion

30 dB

40 dB

Desired channel 3dB above the sensitivity limit

Blocking Performance

±1 MHz offset 50 dB


863-870 MHz ISM Band in Europe (6)Proposed Receiver Specifications

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doc.: IEEE 802.15-09-0480-00-004g


• Absolute minimum requirements regulated by the ETSI EN 300 220* standard– Maximum output power– Transient power– Adjacent Channel Power (ACP) – Spurious Emissions

• Application requirements– Minimum output power at maximum setting

• IEEE 802.15.4-2006: ”... capable of transmitting at least –3 dBm”

Transmitter Requirements

* Draft ETSI EN 300 220-1 V2.3.1 (2009-04)


July 2009


doc.: IEEE 802.15-09-0480-00-004g


• FCC Part 15.247 • Frequency band: 902-928 MHz (26 MHz)• Frequency Hopping Spread Spectrum (FHSS) • Max output power:

1 W (+30 dBm) or 250 mW (+24 dBm)• Dynamic power control

902-928 MHz ISM Band in The USA (1)

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• Well known and proven technique

• Required by some regional regulations (e.g. in the USA) for high transmit power levels

– Widely used in the USA

– Limited use in Europe because frequency hopping does not enable higher transmit power. Duty cycle or LBT also apply for FH systems.

• Can be used for co-existence of multiple networks

• Can enable high aggregate throughput

• Inherent frequency diversity mechanism

• Required performance to facilitate frequency hopping is efficiently supported by semiconductor radio devices today

Frequency Hopping Spread Spectrum (FHSS)


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• Regulations allow high degree of flexibility• Smallest channel spacing determined by the lowest

maximum data rate envisioned– Receiver noise bandwidth set according to the data rate

• Widest channel spacing determined by the target number of channels to support a specific frequency hopping scheme– N ≥ 50 for +30 dBm– N ≥ 25 for +24 dBm

• Data rates set by the M-GFSK modulated signals within the channel

Channelization and Data Rates


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doc.: IEEE 802.15-09-0480-00-004g


# Channels Channel Spacing

[kHz]

Modulation Data Rate

[kbps]

Max Output Power [dBm]

100 (2 x 50) 250 2-GFSK 50 +30

100 (2 x 50) 250 2-GFSK 100 +30

100 (2 x 50) 250 4-GFSK 200 +30

• Can facilitate max +30 dBm output power if needed.

• Multiple sets of (offset) channels could be defined to support at least two networks in the same area

– The main coexistence mechanism would still be the use of different hopping sequences

– Although networks share the same frequency range, coexistence is improved by good far-away selectivity, as the networks have a high probability of large frequency spacing at any given moment in time

– Multipath fading mitigation and coexistence with other networks are maximized utilizing the entire frequency band

902-928 MHz ISM Band in The USA (4)Example of Channelization and Data Rates

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doc.: IEEE 802.15-09-0480-00-004g


Example of Channel Plan for 902-928 MHz

• Guard band (500 kHz) on each side

• Multiple co-existing networks possible


F1,1 F1,2 F1,3

F2,1 F2,2 F2,3

T2 T1T3

T1 T2T3

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doc.: IEEE 802.15-09-0480-00-004g


• The Chinese Short Range Device Regulations• Frequency band: 470-510 MHz• Frequency Hopping Spread Spectrum across the

whole 40 MHz band• Max output power: 50 mW (+17 dBm)• Dynamic power control

470-510 MHz ISM Band in China (1)

This proposal is presented as a possible technicalsolution. The suitability of this frequency band for SUNapplications needs to be confirmed and aligned with theappropriate Chinese standardization bodies.

July 2009


doc.: IEEE 802.15-09-0480-00-004g


# Channels Channel Spacing

[kHz]

Modulation Data Rate

[kbps]

Max Output Power [dBm]

150 (3 x 50) 250 2-GFSK 50 +17

150 (3 x 50) 250 2-GFSK 100 +17

150 (3 x 50) 250 4-GFSK 200 +17

• Multiple sets of (offset) channels could be defined to support several co-existing networks in the same area

– The main coexistence mechanism would still be the use of different hopping sequences

– Although networks share the same frequency range, coexistence is improved by good far-away selectivity, as the networks have a high probability of large frequency spacing at any given moment in time

– Multipath fading mitigation and coexistence with other networks are maximized utilizing the entire frequency band


July 2009


doc.: IEEE 802.15-09-0480-00-004g


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Channel Plan for 470-510 MHz• Guard band (1.25 MHz) on each side• Multiple co-existing networks possible


July 2009


doc.: IEEE 802.15-09-0480-00-004g


• Modulation format:– 2-GFSK and 4-GFSK, BT=0.5

• Data rates:– (R1) 50 kbps : 2-GFSK, modulation index 0.9




July 2009


doc.: IEEE 802.15-09-0480-00-004g


RX Parameter Value Conditions

Receiver sensitivity

(R1) 50 kbps

(R2) 100 kbps

(R3) 200 kbps

-95 dBm

-92 dBm

-85 dBm

PER=1%, 20 bytes packet length

Selectivity

Adjacent Channel Rejetion

Alternate Channel Rejetion

30 dB

40 dB


Blocking Performance

±1 MHz offset 50 dB


Proposed Receiver Specifications


July 2009


doc.: IEEE 802.15-09-0480-00-004g


• As support for very long packets is mandatory, a simple low-overhead FEC should be defined for optional use to improve the packet error rate

• Proposal: (128,120,4) extended Hamming code• SECDED: Corrects single bit, detect double bit errors

– Double bit error detection does not improve PER, but is useful for early receive termination when packet is corrupted

• Can also be viewed and implemented as (127,120,3) BCH, extended by an extra parity bit– Generator polynomials: x7+x3+1 (BCH) and x+1 (extra parity)

• After 15 octets of PHY data, one octet containing parity check bits (PCB) is inserted

Simple Low Overhead FEC

July 2009


doc.: IEEE 802.15-09-0480-00-004g


PHY PAYLOAD

CT

RL

15 PHY octets

PC

B 15 PHY octets

PC

B 1-15 PHY octets

PC

BPREAMBLE

SF

D

CR

C(1

6/32

)

LEN

GT

H

Packet Format

July 2009


doc.: IEEE 802.15-09-0480-00-004g


• Whitening is done after FEC octet insertion

• Same LFSR polynomial is used for whitening all the time

• The whitening LFSR is initialized to an unique value based on the channel number used for the packet– This would enable retransmissions on the following channels

to use different whitening for protection from packet data with poor whitening performance

• Data whitening should be optional

Data Whitening

July 2009


doc.: IEEE 802.15-09-0480-00-004g


Proposal Summary

July 2009


doc.: IEEE 802.15-09-0480-00-004g


Thank you!

Doc.: IEEE 802.15-09-0480-00-004g Power and Spectrum Efficient PHY Proposal for 802.15.4g July 2009...

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