Doc.: IEEE 802.15-01/138r0 Submission March 2001 Mauri Honkanen, NokiaSlide 1 Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)

March 2001

Mauri Honkanen, NokiaSlide 1

doc.: IEEE 802.15-01/138r0

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: [Nokia PHY submission to Task Group 4]Date Submitted: [09 March, 2001]Source: [Mauri Honkanen] Company [Nokia]Address [Visiokatu 1, P.O.Box 100, FIN-33721 Tampere, Finland]Voice:[+358 7180 35356], FAX: [+358 7180 35935], E-Mail:[[email protected]]

Re: [Original document]

Abstract: [Submission to Task Group 4 for consideration as the Low Rate PHY for 802.15.4]

Purpose: [Overview of PHY proposal for evaluation]

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.

March 2001


doc.: IEEE 802.15-01/138r0

Submission

Nokia PHYsical layer submission to IEEE 802.15 Task Group 4

Presented byMauri Honkanen

Nokia

March 2001


doc.: IEEE 802.15-01/138r0

Submission

Contents

• Requirements• Operation frequency band and channel

structure• Bit rate, modulation and performance• Link budget• Interference• Implementation examples• Conclusions

March 2001


doc.: IEEE 802.15-01/138r0

Submission

General PHY requirements

• Minimized RF and BB complexity• Very low cost• Strongly minimized power consumption• Relaxed performance requirements• Unlicensed operation frequency band• FCC and ETSI compliant• Mature, low risk approach

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doc.: IEEE 802.15-01/138r0

Submission

Key points

• Proposed PHY optimized for lowest complexity and lowest power consumption

• Device classes introduced for different applications– Communication between different classes is

possible

• Any available, wide enough frequency band can be used (default 2.45 GHz ISM band)

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doc.: IEEE 802.15-01/138r0

Submission

Power consumption and operation time

• Assumed duty cycle 1%• Idle time power consumption assumed to be 1/1000 of power consumption in active mode.

Battery type Voltage [V]

Capacity [mAh] Radio power consumption

(1% duty cycle) [mW]

1 239 days10 24 days

100 2 days1 2.6 years10 97 days

100 10 days1 18.3 years10 1.8 years

100 67 days1 42.1 years10 4.2 years

100 153.5 days

Approximate operation time

Button cell(L = 2.7 mm,dia. = 9.5 mm)

1.5 42

Button cell(L = 5.4 mm,dia. = 11.6 mm)

1.5 170

AAA 1.5 1175

AA 1.5 2700

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doc.: IEEE 802.15-01/138r0

Submission

Implications of power consumption requirements

• Transceiver should consume about 10-25 times less power than current Bluetooth approaches to be feasible for button batteries– It is possible with very low duty cycles (<< 1%)– In active mode the whole transceiver including

digital processing should consume only ~4 mW with small button cell and ~12 mW with large button cell

– Idle time dominates power consumption due to low duty cycles

– Synthesizer is also critical

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doc.: IEEE 802.15-01/138r0

Submission

Operation frequency band• Default is 2.45 GHz ISM band

– Unlicensed and global– Congested resulting in interference– Quite high frequency from minimum implementation

and propagation point of view

• Optional bands: 902-928 MHz in US and 433.050 - 434.790 MHz in Europe– Smaller propagation loss, potentially less interference– Only regionally available

• Any wide enough band available for short-range devices can be used

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Submission

Channel structure #1in 2400-2483.5 MHz

• 83 channels, center frequencies at 2400.5 + k x 1 MHz, where k = 0...82

• Located between Bluetooth channels to suppress interference from and to Bluetooth

2400 2401 2402 2403 2481 2482 24832480

Bluetooth channelsChannels of theproposed system

IEEE 802.11b channelin North America and Europe IEEE 802.11b channel

in Europe

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doc.: IEEE 802.15-01/138r0

Submission

Channel structure #2in 2400-2483.5 MHz

• 83 channels, center frequencies at 2401 + k x 1 MHz, where k = 0...82

• Better compatibility with Bluetooth• Outermost channels benefitially located

2400 2401 2402 2403 2481 2482 24832480

Bluetooth channelsChannels of theproposed system

IEEE 802.11b channelin North America and Europe IEEE 802.11b channel

in Europe

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doc.: IEEE 802.15-01/138r0

Submission

Device classes

• Device classes dependent on applications• Smaller TX power => smaller operating space and

power consumption• Fixed frequency => simpler implementation• Generally, sensitivity is not a crucial item from power

consumption point of view

Device class TX power[dBm]

Sensitivity[dBm]

TX/RX frequency Range[m]

Mini -20...-10 -87 Variable (all channels) 3...10Pico -20...-10 -87 Fixed (only 1 channel) 3...10Beacon -30...-20 -87 Fixed (only 1 channel) 1...3

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Submission

Bit rate and modulation• Maximum physical layer bit rate 200 kbps

• Data rate scalability achieved with lower activity, shorter packets and possible repetition coding

• Long symbol duration results in small ISI in indoor channels• 200 kbps aggregate capacity considered adequate from

application point of view

• 2GFSK modulation with modulation index h = 2...3 and BT = 0.5

• Constant envelope for low power TX architecture• Spectrum efficiency sacrificed for minimum complexity and low

power RX implementation• Relaxed requirements for phase noise, I/Q imperfections and

frequency drift

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doc.: IEEE 802.15-01/138r0

Submission

Modulation spectrum

2GFSK modulation with modulation index h = 2.5, BT = 0.5

-6 -4 -2 0 2 4 6

x 105

-80

-70

-60

-50

-40

-30

-20

-10

0

10

20

Frequency [Hz]

PS

D [d

B]

unfiltered Gaussian filtered (BT = 0.5)

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doc.: IEEE 802.15-01/138r0

Submission

0 5 10 1510

-4

10-3

10-2

10-1

100

C/N [dB]

Bit

err

or

rate

With RX HP filter Without RX HP filter

Performance in AWGN channel

C/NBER = 1e-3 = 13 dB

C/NBER = 1e-3 = 13.5 dB

2GFSK, modulation index h = 2.5, BT = 0.5,f-3 dB, highpass = 50 kHz, f-3 dB, lowpass = 300 kHz

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doc.: IEEE 802.15-01/138r0

Submission

Performance in flat fading Rayleigh channel

0 10 20 30 40 5010

-5

10-4

10-3

10-2

10-1

100

C/N [dB]

Ra

w B

ER

All channels Worst 1% of channels discardedWorst 3% of channels discarded

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Submission

Channel coding

• By default no channel coding of any kind utilized

• Coding does not help much when the transmitted frame is overlapped by high power interference in both frequency and time

• Increases baseband complexity• No need to extend range by means of coding• Real-time services are not in focus

• Reliability ensured by upper layer retransmissions

• If needed, repetition coding can be used• Simple implementation

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Submission

Parameters Value Value Value UnitTransmission power -10 -20 -30 dBmAntenna gain 0 0 0 dBRange 10 3.2 1 mPath loss @ range 60.2 50.3 40.2 dBReceived power (no fading) -70.2 -70.3 -70.2 dBmNoise floor -174 -174 -174 dBm/HzNoise figure + receiver degradation 17 17 17 dBFilter noise bandwidth 600 600 600 kHzC/N @ BER = 1e-3 13 13 13 dBSensitivity -86.2 -86.2 -86.2 dBmFading margin 16.0 15.9 16.0 dB

Link budget at 2.45 GHz

Fading margin of 16 dB ensures that C/N = 13 dB or better in 97% ofthe channels at range of 1/3/10 m.

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Submission

Interference susceptibility

• 2.45 GHz ISM band will be congested• Low power system cannot compete with TX power• Relaxation in interference susceptibility accepted to

alleviate RX linearity requirements• RX linearity requirements similar to Bluetooth (IIP3 =

-15...-20 dBm) would not result in low-power RX, since RX linearity directly affects power consumption

• In case of co-channel interference, strong adjacent channel interference, blocking or intermodulation, packets are retransmitted

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doc.: IEEE 802.15-01/138r0

Submission

Interference susceptibility example:RX IIP3 -30 dBm

• How far away should a simultaneous transmission occur not to block the receiver?

RX (IIP3 -30 dBm)

Bluetooth TXtransmittingat 0 dBm

TX

IEEE 802.11bWLAN TXtransmittingat 20 dBm

Another TX of theproposed systemtransmittingat -10 dBm

0 m 0.3 m 1 m 10 m

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doc.: IEEE 802.15-01/138r0

Submission

Frame structure

• Preamble should be long enough to assist frequency and symbol synchronization– Preamble format and length to be defined later

• Header and payload left to be defined in the MAC layer

Preamble16...40 bits

Header + payload + CRC etc. (defined by MAC layer)

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Submission

TX implementation example

V C O

D ataG auss ian filte ring

XTA L

1/N

1/R

Loop filte rP hase

de tec to rC hargepum p

D/A

March 2001


doc.: IEEE 802.15-01/138r0

Submission

RX implementation example

90 degLO

DD ata

Q

CLK

D -typeflip -flop

I-b ranch

Q -b ranchB andpass filte rs fo rchanne l filte ring and

D C o ffse t rem ova l

L im itingam p lifie rs

LN A

March 2001


doc.: IEEE 802.15-01/138r0

Submission

Conclusions

• Nokia IEEE 802.15.4 physical layer proposal comprising– 200 kbps maximum data rate, scalability achieved

by means of packet sizing– Operation range from 1 to 10 meters– 2GFSK modulation with large modulation index– Two channel arrangements for 2.45 GHz ISM band,

though the system is not limited to that band

• Spectrum efficiency, link performance and interference tolerance sacrificed for minimum power, minimum complexity implementation

Documents

Doc.: IEEE 802.15-01/138r0 Submission March 2001 Mauri Honkanen, NokiaSlide 1 Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)