January 2005
doc.: IEEE 802. 15-05-0022-01-004a
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) dikim@sfu.ca (2) kskwak@inha.ac.kr]
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.
Submission
Slide 1
D. I. Kim, S. Erküçük, K. S. Kwak
January 2005
doc.: IEEE 802. 15-05-0022-01-004a
Proposal for
IEEE 802.15.4 Alternate PHY
M-ary Code Shift Keying/Binary PPM
(MCSK/BPPM) Based Impulse Radio
SFU, Canada & UWB-ITRC, Inha University
Republic of Korea
Submission
Slide 2
D. I. Kim, S. Erküçük, K. S. Kwak
January 2005
doc.: IEEE 802. 15-05-0022-01-004a
Contents
•
•
•
•
•
•
•
•
TG4a Requirements
MCSK/BPPM
PHY TX Structure
TH Code Assignment
Transceiver Architecture
Information Rate
Location Accuracy
Conclusion
Submission
Slide 3
D. I. Kim, S. Erküçük, K. S. Kwak
January 2005
doc.: IEEE 802. 15-05-0022-01-004a
TG4a Requirements
802.15.4a PHY
MCSK/BPPM compared
to TH-BPPM
scalable information rates
Better BER performance at the
same/higher information rates and
lower transmit power
high precision ranging/
location
Improved ranging/location
precision capability
low power consumption
Lower transmit power at the
same/higher information rates and
better BER performance
low complexity and cost
No new circuit is needed / simple
transceiver structure
*MCSK/BPPM: M-ary Code Shift Keying/Binary Pulse Position Modulation
**TH-BPPM: Time Hopping Binary Pulse Position Modulation
Submission
Slide 4
D. I. Kim, S. Erküçük, K. S. Kwak
January 2005
doc.: IEEE 802. 15-05-0022-01-004a
MCSK/BPPM
MCSK: M-ary Code Shift Keying
BPPM: Binary Pulse Position Modulation
TX
TH PPM – user #1
d (1)  1 1 0 1 0 1 . . .
1
1
0
1
TH-BPPM
t
Tb
0
1 user specific TH code
2Tb
3Tb
only for
multiple access
MCSK/BPPM – user #1
d (1)  1 1 0 1 0 1 . . .
110
TH-BPPM
M=4
choose
a code
M user specific TH codes
Tb
…
2Tb
t
3Tb
1 TH code
c3
for multiple access and data modulation
Submission
0
101
Slide 5
Tb : Bit time
T f : Frame time
D. I. Kim, S. Erküçük, K. S. Kwak
January 2005
doc.: IEEE 802. 15-05-0022-01-004a
PHY TX Structure (1/2)
TX
- TH codes are periodic with Np
- each pulse should be repeated Ns times
- Np/Ns=k is an integer
M user specific TH codes
Example: M  4, N p  8, N s  4
 c 0  7
 c  3
TH   1   
c 2   5
  
c 3  2
d  1 0 1 1...
MCSK
C2
5
8
8 2 3 6 4 1 5
6 5 2 8 7 4 1
8 7 3 1 4 2 6

4 8 6 3 7 5 1
7
3
0
Tb
1
4
2
6
2Tb
t
0
Tf
2T f
3T f
4T f
d  1 0 1 1...
6T f
7T f
8T f
Tb : Bit time
T f : Frame time
BPPM
Submission
5T f
Slide 6
D. I. Kim, S. Erküçük, K. S. Kwak
January 2005
doc.: IEEE 802. 15-05-0022-01-004a
PHY TX Structure (2/2)
TX
- TH codes are periodic with Np
- each pulse should be repeated Ns times
- 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
N p / Ns  1
M 4
2 bits (MCSK)
1 bit (BPPM)
0
N p / Ns  1
M 8
Info.
BER
rate performance
Tb
Np/Ns same
M increasing
3 bits (MCSK)
1 bit (BPPM)
0
Tb
M same
N p / Ns  2
3 bits (MCSK)
1 bit (BPPM)
M 8
0
1 bit (BPPM)
Np/Ns increasing
2Tb
Tb
Tb : Bit time T f :
Submission
Slide 7
Frame time
D. I. Kim, S. Erküçük, K. S. Kwak
January 2005
doc.: IEEE 802. 15-05-0022-01-004a
TH Code Assignment (1/2)
Nu N p M
Each user has M user specific TH codes
TX
sample-long sequence
Generation of TH codes – “Case 1: random assignment”
1 0 1 1 1 0 0 1 0 1 0 0 1 1 0 1 1 1 0 1 0 0 0 1 0 1 0 1 0 0 ...
m-sequence:
46
Np  4
M 4
46 20
2l  N h ; l  6, N h  64
For Tf = 100ns, Tc = 1ns:
100 slots for multiple access
Tf
0
NO!
20
55
c3
c2
c2
c3
55 17 20 13 12 31 61 14 56 5 7 24 26 53 45 35 2 ...
c0
c0
c1
c1
user #2
user #1
N u N p  N u N p  M  1
Submission
?
Slide 8
D. I. Kim, S. Erküçük, K. S. Kwak
January 2005
doc.: IEEE 802. 15-05-0022-01-004a
TH Code Assignment (2/2)
Generation of TH codes – “Case 2: no overlapping”
user #1
46
user #2
20 55 17 20 13 12 31 61 14 56 5 7 24 26 53 45 35 2 ...
user #2
user #1
Np  4
M 4
46 20 55 17
20 55 17 20
55 17 20 13
17 20 13 12
17 13 12 31
no collisions allowed
within user codes
Submission
TX
61 14
...
user #k
56 5
N u N p  N u N p  M  1  n
n: number of overlaps
Slide 9
D. I. Kim, S. Erküçük, K. S. Kwak
January 2005
doc.: IEEE 802. 15-05-0022-01-004a
General Modulation Format
•
•
•
•
Fixed signal space
Increased information rate

log 2 M
Rs  1 

N p / Ns

Extra information
Random selection of
TH codesImproved spectrum
Submission
TX
Slide 10

 R


D. I. Kim, S. Erküçük, K. S. Kwak
January 2005
doc.: IEEE 802. 15-05-0022-01-004a
Receiver Structure - MLSE
M
RX
M
template signals
2M
Np/Ns
hardware structure
1
Submission
computation complexity
2
correlator
Slide 11
N p / N s 
M
D. I. Kim, S. Erküçük, K. S. Kwak
January 2005
doc.: IEEE 802. 15-05-0022-01-004a
Information Rate (1/3)
 log 2 M 
 R
Rs  1 
 N /N 
p
s 

A
TH-BPPM
Ns = 2, M=1
Info. rate Rs
0
MCSK/BPPM
“Constant Energy/Bit” Constraint
Ns = 2, Np=2, M=2
MCSK/BPPM
“Constant Power” Constraint
Ns = 2, Np=2, M=2
Tf
R
2T f
A’
2R
0
Tf
2T f
A
2R
0
Tf
2T f
A’
MCSK/BPPM (same info. rate)
“Constant Power” Constraint
Ns = 2, Np=2, M=2
R
0
T f
2T f
A  1 
log 2 M
A
N p / Ns
can be adjusted to achieve higher information rate at lower transmit T   1  log 2 M T
f
 N /N  f
power and still maintain better BER performance at the same time
p
s 

Submission
Slide 12
D. I. Kim, S. Erküçük, K. S. Kwak
January 2005
doc.: IEEE 802. 15-05-0022-01-004a
Information Rate (2/3)
MCSK/BPPM “Constant Power”
Constraint for Ns = 1, M=8
A
Np
Ns
0
1
Scalable info. rates
Tf
A’=2A
0
4R  R
Tf
2T f
3T f
T f  4T f
 log 2 M 
 R
Rs  1 
 N /N 
p
s 

BER performance
(wrt TH-BPPM)
- increased SNR
- reduced collusions
- no processing gain
- not much improvement
A
Np
Ns
0
2
Tf
2T f
2.5R  R
A’=1.58A
0
Tf
2T f T f 3T f
Tf
2T f
4T f
2T f  5T f
A
Np
Ns
3
0
3T f
2R  R
A’=1.41A
0
Submission
Tf
T f  2T f
3T f
- increased SNR
- reduced collusions
- processing gain
- improved BER
- TX power can be lowered
- info rate can be increased
A  1 
log 2 M
A
N p / Ns
 log 2 M 
T
T f  1 
 N /N  f
p
s 

4T f
5T f
6T f
Slide 13
D. I. Kim, S. Erküçük, K. S. Kwak
January 2005
doc.: IEEE 802. 15-05-0022-01-004a
Information Rate (3/3)
“Constant Power” Constraint
 Improved performance at the same information rate for M=8
Submission
Slide 14
D. I. Kim, S. Erküçük, K. S. Kwak
January 2005
doc.: IEEE 802. 15-05-0022-01-004a
Location Accuracy
Step 0
Procedure
Result
Initial conditions
for TH-BPPM
R0 (information rate);
BER0 (performance)
TX0 (power)
MCSK/BPPM
“Constant Power” Constraint
Comment
R1  R0 ;
Step 1
Increase M
BER1  BER0 ;
TX 1  TX 0
Step 2
R1  R2  R0 ;
Increase Np/Ns
BER1  BER2 ;
TX 2  TX 0
Step 3
Increase T’f
R1  R2  R3  R0 ;
BER2  BER3 ;
BER2 may or may not be
less than BER0
BER3 may or may not be
less than BER0
TX 0  TX 3
R4  R3  R0 ;
Step 4
Increase A’
BER3  BER4 & BER0  BER4 ;
TX 0  TX 4  TX 3
Increased frame time with
longer observation period,
higher information rate,
better BER performance
and lower transmit power
Accurate Ranging/Location
Submission
Slide 15
D. I. Kim, S. Erküçük, K. S. Kwak
January 2005
doc.: IEEE 802. 15-05-0022-01-004a
Conclusion
• MCSK/BPPM provides:
 increased information rate Simultaneously!
 lower transmit power
 better BER performance
 improved spectral characteristics
• MCSK/BPPM is capable of:
IEEE 802.15.4a PHY
 information rate scalability
 location/ranging accuracy
Submission
Slide 16
D. I. Kim, S. Erküçük, K. S. Kwak
January 2005
doc.: IEEE 802. 15-05-0022-01-004a
Back-up Slides
Submission
Slide 17
D. I. Kim, S. Erküçük, K. S. Kwak
January 2005
doc.: IEEE 802. 15-05-0022-01-004a
MCSK/BPPM
“Constant Power” Constraint
Submission
Slide 18
D. I. Kim, S. Erküçük, K. S. Kwak
January 2005
doc.: IEEE 802. 15-05-0022-01-004a
MCSK/BPPM
“Constant Energy/Bit” Constraint
Submission
Slide 19
D. I. Kim, S. Erküçük, K. S. Kwak
January 2005
doc.: IEEE 802. 15-05-0022-01-004a
Effects of TH Code Design on the Performance
MCSK/BPPM “Constant Power” Constraint
Submission
Slide 20
D. I. Kim, S. Erküçük, K. S. Kwak
January 2005
doc.: IEEE 802. 15-05-0022-01-004a
TH Code Spectrum of:
a) TH-BPPM, Np=10
b) ideal MCSK/BPPM, Np 
c) realistic MCSK/BPPM
Fig. a. TH-BPPM
Fig. b. ideal MCSK/BPPM
Submission
Fig. c. realistic MCSK/BPPM
Slide 21
D. I. Kim, S. Erküçük, K. S. Kwak