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Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: M -ary Code Shift Keying/Binary PPM (MCSK/BPPM) Based Impulse Radio Date Submitted: January 2005 Source: [Dong In Kim (1), Serhat Erküçük (1), Kyung Sup Kwak (2) ]

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

Submission Title:M-ary Code Shift Keying/Binary PPM (MCSK/BPPM) Based Impulse Radio

Date Submitted: January 2005

Source: [Dong In Kim (1), Serhat Erküçük (1), Kyung Sup Kwak (2)]

Company: [(1) Simon Fraser University, (2)UWB-ITRC, Inha University]

Address: [(1) School of Engineering Science, 8888 University Drive, Burnaby, BC

V5A 1S6, Canada (2) 253 Yonghyun-Dong, Nam-Gu, #401, Venture Bldg.

Incheon, 402-751 Korea]

Voice: [+1 (604) 291-3248], Fax: [(1) +1 (604) 291-4951 (2) +82-32-876-7349]

E-Mail: [(1) [email protected] (2) [email protected]]

Abstract: [Proposed modulation format increases the ranging and location capability of time hopping impulse radios]

Purpose: [Proposal for the IEEE802.15.4a standard]

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.


Proposal for Area Networks (WPANs)IEEE 802.15.4 Alternate PHY

M-ary Code Shift Keying/Binary PPM

(MCSK/BPPM) Based Impulse Radio

SFU, Canada & UWB-ITRC, Inha UniversityRepublic of Korea


Motivation Area Networks (WPANs)

  • MCSK/BPPM increases the location/ranging capability of existing Time Hopping (TH) Impulse Radios (IRs)

  • H/W complexity is not increased

  • Same signal space with respect to TH-BPPM

  • “MCSK” can be applied to other TH-IRs; eg. MCSK/BPSK


Contents Area Networks (WPANs)

  • TG4a Requirements

  • MCSK/BPPM

  • PHY TX Structure

  • TH Code Assignment

  • Transceiver Architecture

  • Information Rate

  • Location Accuracy

  • Conclusion


TG4a Requirements Area Networks (WPANs)

*MCSK/BPPM: M-ary Code Shift Keying/Binary Pulse Position Modulation

**TH-BPPM: Time Hopping Binary Pulse Position Modulation


t Area Networks (WPANs)

t

0

0

only for

multiple access

c3

for multiple access and data modulation

MCSK/BPPM

MCSK: M-ary Code Shift Keying

BPPM: Binary Pulse Position Modulation

TX

TH PPM – user #1

1

1

0

1

TH-BPPM

1 user specific TH code

MCSK/BPPM – user #1

110

101

TH-BPPM

choose

a code

M=4

M user specific TH codes

1 TH code

Bit time

Frame time


MCSK Area Networks (WPANs)

BPPM

PHY TX Structure (1/2)

TX

  • TH codes are periodic with Np

  • each pulse should be repeated Nstimes

  • - Np/Ns=k is an integer

M user specific TH codes

Example:

C2 5 8 7 3 1 4 2 6

t

0

Bit time

Frame time


PHY TX Structure (2/2) Area Networks (WPANs)

TX

  • TH codes are periodic with Np

  • each pulse should be repeated Nstimes

  • - Np/Ns=k is an integer

M user specific TH codes

Information rate vs. BER performance for fixed Ns and varying Np and M

Scenario

Time domain illustration

Info.

rate

BER

performance

2 bits (MCSK)

1 bit (BPPM)

Np/Ns same

M increasing

3 bits (MCSK)

1 bit (BPPM)

M same

3 bits (MCSK)

1 bit (BPPM)

1 bit (BPPM)

Np/Ns increasing

Frame time

Bit time


46 20 55 Area Networks (WPANs)

c3

c3

c2

c2

c0

c0

c1

c1

user #2

user #1

TH Code Assignment (1/2)

TX

?

Each user has

M user specific TH codes

sample-long sequence

NO!

Generation of TH codes – “Case 1: random assignment”

For Tf = 100ns, Tc = 1ns:

100 slots for multiple access

0

m-sequence:


user #2 Area Networks (WPANs)

user #1

n: number of overlaps

TH Code Assignment (2/2)

TX

Generation of TH codes – “Case 2: no overlapping”

. . .

user #2

user #k

user #1

no collisions allowed

within user codes


General Modulation Format

TX

  • Extra information

  • Random selection of

    TH codesImproved spectrum


Receiver Structure - MLSE Area Networks (WPANs)

RX

M

M

template signals

2M

Np/Ns

hardware structure

computation complexity

correlator


can be adjusted to achieve higher information rate at lower transmit

power and still maintain better BER performance at the same time

Information Rate (1/3)

A

TH-BPPM

Ns = 2, M=1

Info. rate Rs

R

2

0

A’

MCSK/BPPM

“Constant Energy/Bit” Constraint

Ns = 2, Np=2, M=2

2R

2

0

A

MCSK/BPPM

“Constant Power” Constraint

Ns = 2, Np=2, M=2

2R

2

0

A’

R

MCSK/BPPM (same info. rate)

“Constant Power” Constraint

Ns = 2, Np=2, M=2

2

0


Information Rate (2/3) transmit

MCSK/BPPM “Constant Power” Constraint for Ns = 1, M=8

A

BER performance

(wrt TH-BPPM)

Scalable info. rates

0

A’=2A

4R  R

- increased SNR

- reduced collusions

- no processing gain

- not much improvement

0

A

0

- increased SNR

- reduced collusions

- processing gain

- improved BER

- TX power can be lowered

- info rate can be increased

2.5R  R

A’=1.58A

0

A

0

2R  R

A’=1.41A

0


Information Rate (3/3) transmit

  • “Constant Power” Constraint

  • Improved performance at the same information rate for M=8


Location Accuracy transmit

MCSK/BPPM

“Constant Power” Constraint

Procedure

Result

Comment

R0 (information rate);

BER0(performance)

TX0 (power)

Initial conditions

for TH-BPPM

Step 0

Step 1

Increase M

Step 2

BER2may or may not be

less than BER0

Increase Np/Ns

BER3may or may not be

less than BER0

Step 3

Increase T’f

Increased frame time with

longer observation period,

higher information rate,

better BER performance

and lower transmit power

Step 4

Increase A’

Accurate Ranging/Location


Simultaneously! transmit

IEEE 802.15.4a PHY

Conclusion

  • MCSK/BPPM provides:

     increased information rate

     lower transmit power

     better BER performance

     improved spectral characteristics

  • MCSK/BPPM is capable of:

     information rate scalability

     location/ranging accuracy


Back-up Slides transmit


MCSK/BPPM transmit

“Constant Power” Constraint


MCSK/BPPM transmit

“Constant Energy/Bit” Constraint


Effects of TH Code Design on the Performance transmit

MCSK/BPPM “Constant Power” Constraint


Fig. a. TH-BPPM

Fig. b. ideal MCSK/BPPM

Fig. c. realistic MCSK/BPPM


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