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

July 2003

A. Batra, Texas Instruments et al.Slide 1

doc.: IEEE 802.15-03/267r1

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: [Multi-band OFDM Physical Layer Proposal]Date Submitted: [14 July, 2003]Source: [Presenter: Anuj Batra] Company [Texas Instruments] [see page 2,3 for the complete list of company names and authors]

Address [12500 TI Blvd, MS 8649, Dallas, TX 75243]Voice:[214-480-4220], FAX: [972-761-6966], E-Mail:[[email protected]]

Re: [This submission is in response to the IEEE P802.15 Alternate PHY Call for Proposal (doc. 02/372r8) that was issued on January 17, 2003.]

Abstract: [This document describes the Multi-band OFDM proposal for IEEE 802.15 TG3a.]

Purpose: [For discussion by IEEE 802.15 TG3a.]

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.

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Submission

This contribution is a technical merger between*:

Texas Instrument [03/141]: Batra\

andfemto Devices [03/101]: CheahFOCUS Enhancements [03/103]: BoehlkeGeneral Atomics [03/103]: EllisInstitute for Infocomm Research [03/107]: ChinIntel [03/109]: BrabenacMitsubishi Electric [03/111]: MolischPanasonic [03/121]: MoPhilips [03/125]: KerrySamsung Advanced Institute of Technology [03/135]: KwonSamsung Electronics [03/133]: ParkSONY [03/137]: FujitaStaccato Communications [03/099]: AielloTime Domain [03/143]: KellyWisair [03/151]: Shor

* For a complete list of authors, please see page 3.

July 2003


doc.: IEEE 802.15-03/267r1

Submission

Authorsfemto Devices: J. CheahFOCUS Enhancements: K. Boehlke General Atomics: J. Ellis, N. Askar, S. Lin, D. Furuno, D. Peters, G. Rogerson, M. WalkerInstitute for Infocomm Research: F. Chin, Madhukumar, X. Peng, SivanandIntel: J. Foerster, V. Somayazulu, S. Roy, E. Green, K. Tinsley, C. Brabenac, D. Leeper, M. HoMitsubishi Electric: A. F. Molisch, Y.-P. Nakache, P. Orlik, J. ZhangPanasonic: S. MoPhilips: C. Razzell, D. Birru, B. Redman-White, S. KerrySamsung Advanced Institute of Technology: D. H. Kwon, Y. S. KimSamsung Electronics: M. ParkSONY: E. Fujita, K. Watanabe, K. Tanaka, M. Suzuki, S. Saito, J. Iwasaki, B. HuangStaccato Communications: R. Aiello, T. Larsson, D. Meacham, L. MuckeTexas Instruments: A. Batra, J. Balakrishnan, A. Dabak, R. Gharpurey, J. Lin, P. Fontaine,

J.-M. Ho, S. Lee, M. Frechette, S. March, H. YamaguchiTime Domain: J. Kelly, M. PendergrassWisair: G. Shor, Y. Knobel, D. Yaish, S. Goldenberg, A. Krause, E. Wineberger, R. Zack, B.

Blumer, Z. Rubin, D. Meshulam, A. Freund

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doc.: IEEE 802.15-03/267r1

Submission

Overview of OFDM

OFDM was invented more than 40 years ago.

OFDM has been adopted for several technologies: Asymmetric Digital Subscriber Line (ADSL) services. IEEE 802.11a/g. IEEE 802.16a. Digital Audio Broadcast (DAB). Digital Terrestrial Television Broadcast: DVD in Europe, ISDB in Japan

OFDM is also being considered for 4G, IEEE 802.11n, IEEE 802.16, and IEEE 802.20.

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Submission

Strengths of OFDM

OFDM is spectrally efficient. IFFT/FFT operation ensures that sub-carriers do not interfere with each

other.

OFDM has an inherent robustness against narrowband interference. Narrowband interference will affect at most a couple of tones. Information from the affected tones can be erased and recovered via the

forward error correction (FEC) codes.

OFDM has excellent robustness in multi-path environments. Cyclic prefix preserves orthogonality between sub-carriers. Cyclic prefix allows the receiver to capture multi-path energy more

efficiently.

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Submission

Worldwide Compliance

Bands and tones can be dynamically turned on and off in order to comply with changing world-wide regulations.

By using OFDM, small and narrow bandwidths can easily be protected by turning off tones near the frequencies of interest.

For example, consider the radio-astronomy bands allocated in Japan. Only need to zero out a few tones in order to protect these services.

Channel #1 - Typical OFDM waveform f Channel #1 - Waveform with J apaneseradioastronomical bands protected.

f

3260 - 3267 MHz3332 - 3339 MHz3345.8 - 3352.5 MHz

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Submission

Details of the Multi-band OFDM System

*More details about the Multi-band OFDM system can be found in the latest version of 03/268.

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Submission

Overview of Multi-band OFDM

Basic idea: divide spectrum into several 528 MHz bands.

Information is transmitted using OFDM modulation on each band. OFDM carriers are efficiently generated using an 128-point IFFT/FFT. Internal precision is reduced by limiting the constellation size to QPSK.

Information bits are interleaved across all bands to exploit frequency diversity and provide robustness against multi-path and interference.

60.6 ns cyclic prefix provides robustness against multi-path even in the worst channel environments.

9.5 ns guard interval provides sufficient time for switching between bands.

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Submission

Multi-band OFDM: TX Architecture

Block diagram of an example TX architecture:

Architecture is similar to that of a conventional and proven OFDM system. Can leverage existing OFDM solutions for the development of the Multi-band OFDM physical layer.

For a given superframe, the time-frequency code is specified in the beacon by the PNC. The time-frequency code is changed from one superframe to another in order to randomize multi-piconet interference.

DACScramblerConvolutional

EncoderPuncturer

BitInterleaver

ConstellationMapping

IFFTInsert Pilots

Add CP & GI

Time-Frequency Code

exp(j2fct)

InputData

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doc.: IEEE 802.15-03/267r1

Submission

Multi-band OFDM System Parameters

System parameters for mandatory and optional data rates:

Info. Data Rate 55 Mbps* 80 Mbps** 110 Mbps* 160 Mbps** 200 Mbps* 320 Mbps** 480 Mbps**

Modulation/Constellation OFDM/QPSK OFDM/QPSK OFDM/QPSK OFDM/QPSK OFDM/QPSK OFDM/QPSK OFDM/QPSK

FFT Size 128 128 128 128 128 128 128

Coding Rate (K=7) R = 11/32 R = 1/2 R = 11/32 R = 1/2 R = 5/8 R = 1/2 R = 3/4

Spreading Rate 4 4 2 2 2 1 1

Information Tones 25 25 50 50 50 100 100

Data Tones 100 100 100 100 100 100 100

Info. Length 242.4 ns 242.4 ns 242.4 ns 242.4 ns 242.4 ns 242.4 ns 242.4 ns

Cyclic Prefix 60.6 ns 60.6 ns 60.6 ns 60.6 ns 60.6 ns 60.6 ns 60.6 ns

Guard Interval 9.5 ns 9.5 ns 9.5 ns 9.5 ns 9.5 ns 9.5 ns 9.5 ns

Symbol Length 312.5 ns 312.5 ns 312.5 ns 312.5 ns 312.5 ns 312.5 ns 312.5 ns

Channel Bit Rate 640 Mbps 640 Mbps 640 Mbps 640 Mbps 640 Mbps 640 Mbps 640 Mbps

Multi-path Tolerance 60.6 ns 60.6 ns 60.6 ns 60.6 ns 60.6 ns 60.6 ns 60.6 ns

* Mandatory information data rate, ** Optional information data rate

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doc.: IEEE 802.15-03/267r1

Submission

Simplified TX Analog Section

For rates up to 200 Mb/s, the input to the IFFT is forced to be conjugate symmetric (for spreading gains 2). Output of the IFFT is REAL.

The analog section of TX can be simplified when the input is real: Need to only implement the “I” portion of DAC and mixer. Only requires half the analog die size of a complete “I/Q” transmitter.

For rates > 200 Mb/s, need to implement full “I/Q” transmitter.

DACScramblerConvolutional

EncoderPuncturer

BitInterleaver

ConstellationMapping

IFFTInsert Pilots

Add CP & GI

Time Frequency Code

cos(2fct)

InputData

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Submission

More Details on the OFDM Parameters

By using a contiguous set of orthogonal carriers, the transmit spectrum will always occupy a bandwidth greater than 500 MHz.

Total of 128 tones: 100 data tones used to transmit information (constellation: QPSK). 12 pilot tones used for carrier and phase tracking. 10 user-defined pilot tones. Remaining 6 tones including DC are NULL tones.

User-defined pilot tones: Carry no useful information. Energy is placed on these tones to ensure that the spectrum has a bandwidth

greater than 500 MHz. Can trade the amount of energy placed on tones for relaxing analog filtering

specifications. Ultimately, the amount of energy placed on these tones is left to the implementer.

Provides a level of flexibility for the implementer.

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Submission

Band Plan (1)

Group the 528 MHz bands into 4 distinct groups.

Group A: Intended for 1st generation devices (3.1 – 4.9 GHz). Group B: Reserved for future use (4.9 – 6.0 GHz). Group C: Intended for devices with improved SOP performance (6.0 – 8.1 GHz). Group D: Reserved for future use (8.1 – 10.6 GHz).

f3432MHz

3960MHz

4488MHz

5016MHz

5808MHz

6336MHz

6864MHz

7392MHz

7920MHz

8448MHz

8976MHz

9504MHz

10032MHz

Band#1

Band#2

Band#3

Band#4

Band#5

Band#6

Band#7

Band#8

Band#9

Band#10

Band#11

Band#12

Band#13

GROUP A GROUP B GROUP C GROUP D

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Submission

Band Plan (2)

The relationship between the center frequency fc and the band number nb is:

BAND_ID (nb) LowerFrequency

(fl)

CenterFrequency

(fc)

HigherFrequency

(fh)

BAND_ID (nb) LowerFrequency

(fl)

Center

Frequency(fc)

HigherFrequency

(fh)

1 3168 MHz 3432 MHz 3696 MHz 8 7128 MHz 7392 MHz 7656 MHz






7 6600 MHz 6864 MHz 7128 MHz

13,,55283168

4,,15282904)(

bb

bbbc nn

nnnf

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Submission

Multi-mode Multi-band OFDM Devices (1)

Having multiple groups of bands enables multiple modes of operations for multi-band OFDM devices.

Different modes for multi-band OFDM devices are:

Future expansion into groups B and D will enable an increase in the number of modes.

Mode Frequency of Operation Number of Bands Mandatory / Optional

1 Bands 1–3 (A) 3 Mandatory

2 Bands 1–3, 6–9 (A,C) 7 Optional

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Submission

Multi-mode Multi-band OFDM Devices (2)

Frequency of operation for a Mode 1 device:

Frequency of operation for a Mode 2 device:

f3432MHz

3960MHz

4488MHz

Band#1

Band#2

Band#3

f3432MHz

3960MHz

4488MHz

6336MHz

6864MHz

7392MHz

7920MHz

Band#1

Band#2

Band#3

Band#6

Band#7

Band#8

Band#9

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Submission

Frequency Synthesis (1)

Example: frequency synthesis for Mode 1 (3-band) device:

A single PLL can also be used to generate the center frequencies for a Mode 2 (7-band) device.

528 MHz

PLL

/ 8 / 2

SSB

4224 MHz

264 MHz

SSB

Select

DesiredCenter

Frequency

SamplingClock

792 MHz

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Submission

Frequency Synthesis (2) Circuit-level simulation of frequency synthesis:

Nominal switching time = ~2 ns.

Need to use a slightly larger switching time to allow for process and temperature variations.

Switching Time = ~2 nsSwitching Time = ~2 ns

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Submission

Multi-band OFDM: PLCP Frame Format

PLCP frame format:

Rates supported: 55, 80, 110, 160, 200, 320, 480 Mb/s. Support for 55, 110, and 200 Mb/s is mandatory.

Mode 1 (3-band): Preamble + Header length = 11.56 s. Burst preamble + Header length = 4.69 s.

Mode 2 (7-band): Preamble + Header length = 14.06 s. Burst preamble + Header length = 7.19 s.

Header is sent at an information data rate of 55 Mb/s. Maximum frame payload supported is 4095 bytes.

PLCP PreamblePHY

HeaderMAC

HeaderHCS

Frame PayloadVariable Length: 0 4095 bytes

PadBits

TailBits

55 Mb/s 55, 80, 110, 160, 200, 320, 480 Mb/s

RATE3 bits

Reserved1 bit

LENGTH12 bits

Scrambler Init2 bits

TailBits

FCS

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doc.: IEEE 802.15-03/267r1

Submission

Multiple Access

Multiple piconet performance is governed by the bandwidth expansion factor.

Bandwidth expansion can be achieved using any of the following techniques or combination of techniques: Spreading, Time-frequency interleaving, Coding Ex: Multi-band OFDM obtains its BW expansion by using all 3 techniques.

Time Frequency Codes:

Channel Number

PreamblePattern

Mode 1 DEV: 3-band

Length 6 TFC

Mode 1 DEV: 7-band

Length 7 TFC

1 1 1 2 3 1 2 3 1 2 3 4 5 6 7

2 2 1 3 2 1 3 2 1 7 6 5 4 3 2

3 3 1 1 2 2 3 3 1 4 7 3 6 2 5

4 4 1 1 3 3 2 2 1 3 5 7 2 4 6

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Submission

PLCP Preamble (1)

Multi-band OFDM preamble is composed of 3 sections: Packet sync sequence: used for packet detection. Frame sync sequence: used for boundary detection. Channel estimation sequence: used for channel estimation.

Packet and frame sync sequences are constructed from the same hierarchical sequence.

Correlators for hierarchical sequences can be implemented efficiently: Low gate count. Extremely low power consumption.

Sequences are designed to be the most robust portion of the packet.

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Submission

PLCP Preamble (2) Preamble needs to be designed to allow both Mode 1 (3-band) and Mode 2

(7-band) devices to operate in the same piconet. All devices in the same piconet must be able to detect the preamble and demodulate

PHY/MAC header.

Preamble structure for Mode 1 (3-band) device:

End of synchronization pattern [p1,p2,p3] is used to indicate that the interleaving sequence remains constant throughout the packet.

Time

Band #1

Synchronizaton(24 symbols)

11.5625 usec (Preamble + Header)

End of SynchIndicator

Band #2

Band #3

Band #6

Band #7

Band #8

Band #9

ChannelEstimation

Header PayloadSynchronization

Channel Estimation

Header

Payload

p

p

p

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Submission

PLCP Preamble (3) Preamble structure for Mode 2 (7-band) device:

Preamble/header are transmitted on bands 1–3 using length 6 interleaving sequences, so Mode 1 (3-band) devices can correctly decode the header.

End of synchronization pattern [p4,p5,p6] is used to indicate the transition to length 7 interleaving sequence.

p

p

p

Time

Band #1

Synchronizaton(24 symbols)

14.0625 usec (Preamble + Header)

End of SynchIndicator

Band #2

Band #3

Band #6

Band #7

Band #8

Band #9

Channel EstimationLower 3 Bands

Synchronization

Channel Estimation

Header

Payload

Channel Estimation Upper 4 Bands+

Header on Lower 3 Bands Payload

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doc.: IEEE 802.15-03/267r1

Submission

PLCP Preamble (4)

In the multiple overlapping piconet case, it is desirable to use different hierarchical preambles for each of the piconets.

Basic idea: define 4 hierarchical preambles, with low cross-correlation values.

Preambles are generated by spreading a length 16 sequence by a length 8 sequence.

Sequence A(length 16)

Sequence B(length 8)

SpreaderSequence C(length 128)

Preamble Pattern Sequence A

1 1 1 1 1 -1 -1 -1 1 -1 1 -1 1 1 -1 1 1

2 -1 1 1 -1 1 -1 -1 -1 -1 1 1 1 -1 1 1 1

3 -1 1 1 1 1 1 -1 -1 1 1 -1 1 -1 1 1 -1

4 1 -1 -1 1 1 -1 1 -1 1 -1 -1 -1 -1 -1 -1 1

Preamble Pattern Sequence B

1 1 1 -1 1 1 -1 -1 -1

2 -1 1 -1 -1 1 1 1 -1

3 -1 1 -1 -1 1 1 1 -1

4 1 1 -1 1 1 -1 -1 -1

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Submission

Link Budget and Receiver Sensitivity

Assumption: Mode 1 DEV (3-band), AWGN, and 0 dBi gain at TX/RX antennas.

Parameter Value Value Value

Information Data Rate 110 Mb/s 200 Mb/s 480 Mb/s

Average TX Power -10.3 dBm -10.3 dBm -10.3 dBm

Total Path Loss 64.2 dB

(@ 10 meters)

56.2 dB

(@ 4 meters)

50.2 dB

(@ 2 meters)

Average RX Power -74.5 dBm -66.5 dBm -60.5 dBm

Noise Power Per Bit -93.6 dBm -91.0 dBm -87.2 dBm

CMOS RX Noise Figure 6.6 dB 6.6 dB 6.6 dB

Total Noise Power -87.0 dBm -84.4 dBm -80.6 dBm

Required Eb/N0 4.0 dB 4.7 dB 4.9 dB

Implementation Loss 2.5 dB 2.5 dB 3.0 dB

Link Margin 6.0 dB 10.7 dB 12.2 dB

RX Sensitivity Level -80.5 dBm -77.2 dBm -72.7 dB

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Submission

Link Budget and Receiver Sensitivity

Assumption: Mode 2 DEV (7-band), AWGN, and 0 dBi gain at TX/RX antennas.

Parameter Value Value Value

Information Data Rate 110 Mb/s 200 Mb/s 480 Mb/s

Average TX Power -6.6 dBm -6.6 dBm -6.6 dBm

Total Path Loss 66.6 dB

(@ 10 meters)

58.6 dB

(@ 4 meters)

52.6 dB

(@ 2 meters)

Average RX Power -73.2 dBm -65.2 dBm -59.2 dBm

Noise Power Per Bit -93.6 dBm -91.0 dBm -87.2 dBm

CMOS RX Noise Figure 8.6 dB 8.6 dB 8.6 dB

Total Noise Power -85.0 dBm -82.4 dBm -78.6 dBm

Required Eb/N0 4.0 dB 4.7 dB 4.9 dB

Implementation Loss 2.5 dB 2.5 dB 3.0 dB

Link Margin 5.3 dB 10.0 dB 11.5 dB

RX Sensitivity Level -78.5 dBm -75.2 dBm -70.7 dB

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Submission

System Performance (Mode 1: 3-band)

The distance at which the Multi-band OFDM system can achieve a PER of 8% for a 90% link success probability is tabulated below:

* Includes losses due to front-end filtering, clipping at the DAC, ADC degradation, multi-path degradation, channel estimation, carrier tracking, packet acquisition, etc.

Range* AWGN CM1 CM2 CM3 CM4

110 Mbps 20.5 m 11.5 m 10.9 m 11.6 m 11.0 m

200 Mbps 14.1m 6.9 m 6.3 m 6.8 m 5.0 m

480 Mbps 7.8 m 2.9 m 2.6 m N/A N/A

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Submission

Simultaneously Operating Piconets (1)

Assumptions: Mode 1 DEV (3-band) operating at a data rate of 110 Mbps.

Simultaneously operating piconet performance as a function of the multipath channel environments:

Results incorporate SIR estimation at the receiver.

Channel Environment 1 piconet 2 piconet 3 piconet

CM1 (dint/dref) 0.91 1.18 1.45

CM2 (dint/dref) 0.83 1.24 1.47

CM3 (dint/dref) 0.94 1.21 1.46

CM4 (dint/dref) 1.15 1.53 1.85

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Submission

Simultaneously Operating Piconets (2)

Assumptions: Mode 2 DEV (7-band) operating at a data rate of 110 Mbps.

Simultaneously operating piconet performance as a function of the multipath channel environments:

Results incorporate SIR estimation at the receiver.

Channel Environment 1 piconet 2 piconet 3 piconet

CM1 (dint/dref) 0.47 0.65 0.86

CM2 (dint/dref) 0.43 0.64 0.80

CM3 (dint/dref) 0.49 0.66 0.81

CM4 (dint/dref) 0.61 0.84 1.01

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Submission

Signal Robustness/Coexistence

Assumption: Received signal is 6 dB above sensitivity.

Value listed below are the required distance or power level needed to obtain a PER 8% for a 1024 byte packet and a Mode 1 DEV (3-band).

Coexistence with 802.11a/b and Bluetooth is relatively straightforward because these bands are completely avoided.

Interferer Value

IEEE 802.11b @ 2.4 GHz dint 0.2 meter

IEEE 802.11a @ 5.3 GHz dint 0.2 meter

Modulated interferer* SIR -3.6 dB

Tone interferer* SIR -5.6 dB* Results can be further improved by erasing all the information from the affected band.

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Submission

PHY-SAP Throughput

Assumptions: MPDU (MAC frame body + FCS) length is 1024 bytes. SIFS = 10 s. MIFS = 2 s.

Assumptions: MPDU (MAC frame body + FCS) length is 4024 bytes.

Number of frames Throughput @ 110 Mb/s Throughput @ 200 Mb/s Throughput @ 480 Mb/s

1 Mode 1: 84.8 Mb/sMode 2: 82.7 Mb/s

Mode 1: 130.4 Mb/sMode 2: 125.4 Mb/s

Mode 1: 211.4 Mb/sMode 2: 198.6 Mb/s

5 Mode 1: 94.8 Mb/sMode 2: 92.1 Mb/s

Mode 1: 155.6 Mb/s

Mode 2: 148.5 Mb/s

Mode 1: 286.4 Mb/s

Mode 2: 263.4 Mb/s

Number of frames Throughput @ 110 Mb/s Throughput @ 200 Mb/s Throughput @ 480 Mb/s

1 Mode 1: 102.3 Mb/s Mode 2: 101.5 Mb/s

Mode 1: 175.9 Mb/sMode 2: 173.5 Mb/s

Mode 1: 362.4 Mb/sMode 2: 352.4 Mb/s

5 Mode 1: 105.7 Mb/sMode 2: 104.8 Mb/s

Mode 1: 186.3 Mb/sMode 2: 183.6 Mb/s

Mode 1: 409.2 Mb/sMode 2: 396.5 Mb/s

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Submission

Complexity (1)

Unit manufacturing cost (selected information): Process: CMOS 90 nm technology node in 2005. CMOS 90 nm production will be available from all major SC foundries by early

2004.

Die size for Mode 1 (3-band) device:

Die size for Mode 2 (7-band) device:

Complete Analog* Complete Digital

90 nm 2.7 mm2 1.9 mm2

130 nm 3.0 mm2 3.8 mm2

* Component area.

Complete Analog* Complete Digital

90 nm 2.9 mm2 1.9 mm2

130 nm 3.2 mm2 3.8 mm2

* Component area.

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Submission

Complexity (2)

Active CMOS power consumption for Mode 1 (3-band) and Mode 2 (7-band) devices:

Block Mode1: 90 nm Mode 2: 90 nm Mode 1: 130 nm Mode 2: 130 nm

TX AFE (110, 200 Mb/s) 76 mW 133 mW 91 mW 160 mW

TX Digital (110, 200 Mb/s)

17 mW 17 mW 26 mW 26 mW

TX Total (110 Mb/s) 93 mW 150 mW 117 mW 186 mW

RX AFE (110, 200 Mb/s) 101 mW 155 mW 121 mW 187 mW

RX Digital (110 Mb/s) 54 mW 54 mW 84 mW 84 mW

RX Digital (200 Mb/s) 68 mW 68 mW 106 mW 106 mW

RX Total (110 Mb/s) 155 mW 209 mW 205 mW 271 mW

RX Total (200 Mb/s) 169 mW 223 mW 227 mW 293 mW

Deep Sleep 15 W 15 W 18 W 18 W

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Submission

Complexity (3)

Manufacturability: Leveraging standard CMOS technology results in a straightforward

development effort. OFDM solutions are mature and have been demonstrated in ADSL and

802.11a/g solutions.

Scalability with process: Digital section complexity/power scales with improvements in technology

nodes (Moore’s Law). Analog section complexity/power scales slowly with technology node.

Time to market: the earliest complete CMOS PHY solutions would be ready for integration is 2005.

Size: Solutions for PC card, compact flash, memory stick, SD memory in 2005.

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Submission

Scalability of Multi-band OFDM Data rate scaling: from 55 Mb/s to 480 Mb/s.

Frequency scaling: Mode 1 (3-bands) and optional Mode 2 (7-band) devices. Guaranteed interoperability between different mode devices.

Complexity scaling: Mandatory data rates ( 200 Mbps) only required a single DAC and mixer for the TX

chain reduced complexity. Digital section will scale with future CMOS process improvements. Implementers could always trade-off complexity for performance.

Power scaling: A half-rate Pulse Repetition Frequency (PRF) approach can increase the off time to

enable power saving modes of operation (see back-up slide). Implementers could always trade-off power consumption for range and information

data rate.

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Submission

Comparison of OFDM Technologies Qualitative comparison between Multi-band OFDM and IEEE 802.11a OFDM:

CriteriaMulti-band OFDMStrong Advantage

Multi-band OFDMSlight Advantage

Neutral802.11a

Slight Advantage802.11a

Strong Advantage

PA Power Consumption

ADC Power Consumption

FFT Complexity

Viterbi Decoder Complexity

Band Select FilterPower Consumption

Band Select Filter Area

ADC Precision

Digital Precision

Phase Noise Requirements

Sensitivity to Frequency/Timing Errors

Design of Radio

Power / Mbps1. Assumes a 256-point FFT for IEEE 802.11a device.2. Assumes a 128-point FFT for IEEE 802.11a device.3. Even though the Multi-band OFDM ADC runs faster than the IEEE 802.11a ADC, the bit precision requirements are significantly smaller,

therefore the Multi-OFDM ADC will consume much less power.

1 23

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Submission

Multi-band OFDMAdvantages (1)

Suitable for CMOS implementation (all components).

Only one transmit and one receive chain at all times, even in the presence of multi-path.

Antenna and pre-select filter are easier to design (can possibly use off-the-shelf components).

Early time to market!

Low cost, low power, and CMOS integrated solution leads to:

Early market adoption!

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Submission

Multi-band OFDMAdvantages (2)

Inherent robustness in all the expected multipath environments.

Excellent robustness to ISM, U-NII, and other generic narrowband interference.

Ability to comply with world-wide regulations: Bands and tones can be dynamically turned on/off to comply with

changing regulations.

Coexistence with current and future systems: Bands and tones can be dynamically turned on/off for enhanced

coexistence with the other devices.

Scalability with process: Digital section complexity/power scales with improvements in technology

nodes (Moore’s Law). Analog section complexity/power scales slowly with technology node.

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Submission

Summary

The proposed system is specifically designed to be a low power, low complexity all CMOS solution.

Expected range for 110 Mb/s: 20.5 meters in AWGN, and greater than 11 meters in multipath environments.

Expected power consumption for 110 Mb/s: Mode 1 DEV: 117 mW (TX), 205 mW (RX), 18 W (deep sleep) for 130 nm. Mode 2 DEV: 186 mW (TX), 271 mW (RX), 18 W (deep sleep) for 130 nm.

Multi-band OFDM is coexistence friendly and complies with world-wide regulations.

Multi-band OFDM offers multi-mode devices (scalability).

Multi-band OFDM offers the best trade-off between the various system parameters.

July 2003


doc.: IEEE 802.15-03/267r1

Submission

Backup slides

July 2003


doc.: IEEE 802.15-03/267r1

Submission

Self-evaluation Matrix (1) REF.

IMPORTANCE LEVEL

PROPOSER RESPONSE

Unit Manufacturing Complexity (UMC)

3.1 B +

Signal Robustness Interference And Susceptibility 3.2.2

A +

Coexistence 3.2.3 A +

Technical Feasibility

Manufacturability 3.3.1 A +

Time To Market 3.3.2 A +

Regulatory Impact 3.3.3 A +

Scalability (i.e. Payload Bit Rate/Data Throughput, Channelization – physical or coded, Complexity, Range, Frequencies of Operation, Bandwidth of Operation, Power Consumption)

3.4 A

+

Location Awareness 3.5 C 0

CRITERIA REF.

IMPORTANCE LEVEL

PROPOSER RESPONSE

MAC Enhancements And Modifications

4.1. C +

July 2003


doc.: IEEE 802.15-03/267r1

Submission

Self-evaluation Matrix (2)CRITERIA REF.

IMPORTANCE LEVEL

PROPOSER RESPONSE

Size And Form Factor 5.1 B

+

PHY-SAP Payload Bit Rate & Data Throughput Payload Bit Rate 5.2.1

A +

Packet Overhead 5.2.2 A +

PHY-SAP Throughput 5.2.3 A +

Simultaneously Operating Piconets

5.3 A +

Signal Acquisition 5.4 A +

System Performance 5.5 A +

Link Budget 5.6 A +

Sensitivity 5.7 A +

Power Management Modes 5.8 B +

Power Consumption 5.9 A +

Antenna Practicality 5.10 B +

July 2003


doc.: IEEE 802.15-03/267r1

Submission

Convolutional Encoder

Assume a mother convolutional code of R = 1/3, K = 7. Having a single mother code simplifies the implementation.

Generator polynomial: g0 = [1338], g1 = [1458], g2 = [1758].

Higher rate codes are achieved by puncturing the mother code. Puncturing patterns are specified in latest revision of 03/268.

D D D D D DI nputData

Output Data A

Output Data B

Output Data C

July 2003


doc.: IEEE 802.15-03/267r1

Submission

Bit Interleaver: Mode 1 (3-band)

Bit interleaving is performed across the bits within an OFDM symbol and across at most three OFDM symbols. Exploits frequency diversity. Randomizes any interference interference looks nearly white. Latency is less than 1 s.

Bit interleaving is performed in three stages: First, 3NCBPS coded bits are grouped together. Second, the coded bits are interleaved using a NCBPS3 block symbol

interleaver. Third, the output bits from 2nd stage are interleaved using a (NCBPS/10)10

block tone interleaver. The end results is that the 3NCBPS coded bits are interleaved across 3

symbols and within each symbol.

If there are less than 3NCBPS coded bits, which can happen at the end of the header or near the end of a packet, then the second stage of the interleaving process is skipped.

July 2003


doc.: IEEE 802.15-03/267r1

Submission

Bit Interleaver: Mode 1 (3-band) Ex: Second stage (symbol interleaver) for a data rate of 110 Mbps

Ex: Third stage (tone interleaver) for a data rate of 110 Mbps

NCBPS 3

Read I n

Read Out

x1 x2 ... x300 x1 x4 ... x298 x2 x5 ... x299 x3 x6 ... x300

300 Coded bits = 3 OFDM symbols 300 Coded bits = 3 OFDM symbols

NCBPS/10 10

Read I n

Read Out

y1 y2 ... y300

y1 y11 ... y91 y2 y12 ... y92 ... y10 y20 ... y100y101 y111 ... y191 y102 y112 ... y192 y110 y120 ... y200y201 y211 ... y291 y202 y212 ... y292 y210 y220 ... y300

300 Coded bits = 3 OFDM symbols 300 Coded bits = 3 OFDM symbols

July 2003


doc.: IEEE 802.15-03/267r1

Submission

Frequency Synthesis

Example: frequency synthesis for a Mode 2 (7-band) device:

PLL / 3 / 2 / 2

528MHz

SSB

Select

DesiredCenter

Frequency

SamplingClock

1056MHz

2112MHz

/ 2264MHz

SSB

SSB

6336MHz

SSB

Select

SSB

6336MHz

1584 MHz

792 MHz

4224 MHz

264 MHz

Select

July 2003


doc.: IEEE 802.15-03/267r1

Submission

Multi-band OFDM: RX Architecture

Block diagram of an example RX architecture:

Architecture is similar to that of a conventional and proven OFDM system. Can leverage existing OFDM solutions for the development of the Multi-band OFDM physical layer.

Pre-SelectFilter

LNA

sin(2fct)

cos(2fct)

Syn

chro

niza

tion

Rem

ove

CP

FFT

FEQ

Rem

ove

Pilo

ts

Vit

erbi

Dec

oder

De-

scra

mble

r

AGC

CarrierPhaseand

TimeTracking

De-

Inte

rlea

ver

I

Q

LPF

LPF

VGA

VGA

ADC

ADC

OutputData

July 2003


doc.: IEEE 802.15-03/267r1

Submission

Simulation Parameters

Assumptions: System as defined in 03/268. Clipping at the DAC (PAR = 9 dB). Finite precision ADC (4 bits @ 110/200 Mbps).

Degradations incorporated: Front-end filtering. Multi-path degradation. Clipping at the DAC. Finite precision ADC. Crystal frequency mismatch (20 ppm @ TX, 20 ppm @ RX). Channel estimation. Carrier/timing offset recovery. Carrier tracking. Packet acquisition.

July 2003


doc.: IEEE 802.15-03/267r1

Submission

FFT/IFFT Complexity Number of complex multipliers and complex adders needed per clock cycle for a

128 point FFT.

OFDM efficiently captures multi-path energy with lower complexity!

128-point FFT is realizable in current CMOS technology. A technical contribution (03/213) by Roger Bertschmann (SiWorks, Inc.) shows that they

have a 128-point IFFT/FFT core which can be used in a Multi-band OFDM system. The synthesized core has a gate count of approximately 70K gates in a 130 nm TSMC

process.

Clock Complex Multipliers / clock cycle Complex Adders / clock cycle

102.4 MHz 10 28

128 MHz 8 22.4

ADC528MHz

FFT in terms of

complex multiplies

ADC1024MHz

1 Finger Rake

July 2003


doc.: IEEE 802.15-03/267r1

Submission

System Performance (1)

PER as a function of distance and data rate in an AWGN and CM2 environment for a Mode 1 DEV: 3-band (90% link success probability).

July 2003


doc.: IEEE 802.15-03/267r1

Submission

System Performance (2)

PER as a function of distance and data rate in an CM3 and CM4 environment for a Mode 1 DEV: 3-band (90% link success probability).

July 2003


doc.: IEEE 802.15-03/267r1

Submission

Signal Acquisition

Preamble is transmitted on bands 1–3 and is designed to work at 3 dB below sensitivity for 55 Mbps.

Prob. of false detect (Pf) = 6.2 x 10-4.

The results for prob. of miss detect (Pm) vs. distance @ 110 Mb/s was averaged over 500 noise realization for 100 channels in each channel environment:

The start of a valid OFDM transmission at a receiver sensitivity level -83.5 dBm shall cause CCA to indicate busy with a probability > 90% in 4.69 s.

July 2003


doc.: IEEE 802.15-03/267r1

Submission

Half-Rate Pulse Repetition Factor

It is possible to reduce receiver power consumption by using a half-rate pulse repetition factor scheme (see figure for two possible options).

Digital power consumption can be reduced by 40–50%.

Analog power consumption can also be reduced by turning off some of the analog/RF circuits. Note that circuits with long time constants cannot be turned off. Estimated analog power savings is between 20–40%.

Fa FcFb Fa FcFb

Time

Option #1: ½ Rate Symbol Rate Control (Piconet 1)

Fa FcFb Fa FcFb

Option #2: ½ Rate Hop Frame Rate Control (Piconet 1)

Time

Fa FcFb Fa FcFb Fa FcFb Fa FcFb

Time

Full Rate (Piconet 1)

Fa Fc Fb Fa Fc Fb Fa Fc Fb Fa Fc Fb

Time

Full Rate (Piconet 2)

Documents

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