a new uwb dual pulse transmission and detection...
TRANSCRIPT
A New UWB Dual Pulse Transmission andDetection Technique
Xiaodai Dong
University of Victoria, Victoria, BC, Canada
Alfred Lee
Lei Xiao
University of Notre Dame, Notre Dame, IN, USA
A New UWB Dual Pulse Transmission and Detection Technique – p.1/31
Overview
• Introduction• The UWB Channel Model• The Transmitted Reference (TR) System• The Novel Dual Pulse (DP) System• The Improved DP (iDP) System• Conclusion
A New UWB Dual Pulse Transmission and Detection Technique – p.2/31
Introduction
• Ultra-wideband (UWB) has been proposed as aphysical layer candidate for low cost, short rangewireless personal area networks.
• Estimating the UWB multipath channel andcollecting multipath energy pose challenges toUWB receiver design.
• Transmitted reference (TR) systems employautocorrelation receiver and waive the need toestimate channel path gains and path delays[Hoctor and Tomlinson, UWBST’2002].
A New UWB Dual Pulse Transmission and Detection Technique – p.3/31
Introduction (Cont’d)
• The TR system is simple and robust. Its variantshave been proposed in various literature [Chaoand Scholtz, Franz and Mitra, Zhang and Goeckel,Nekoogar and Dowla].
• Differential detection [Ho et.al.] and pilot waveformassisted modulation [Yang and Giannakis]
• We propose a novel dual pulse (DP) system thatdoubles the data rate of the TR system.
A New UWB Dual Pulse Transmission and Detection Technique – p.4/31
Features of the DP System
• The data rate of the DP system doubles the TR system, while achieving similarperformance.
• The delay unit in the receiver is only half the dual-pulse width, Tw/2 and muchshorter than the frame delay Tf in the TR system. Implementing accurate shortdelays is easier than long delays.
• The DP system is less sensitive to time variation of the channel. Within a fixedchannel coherence time, there are more received reference sub-pulses to beaveraged over to reduce the noise effect.
• The DP system retains the merits of the TR system, such as robust performance,simple implementation and easy timing acquisition.
• Inter-pulse interference in the DP system is not severe.
• The improved dual pulse (iDP) system eliminates the inter-pulse interference inthe DP system.
A New UWB Dual Pulse Transmission and Detection Technique – p.5/31
The UWB Channel Model
• The UWB channel characterization is a subjectarea requiring extensive experiments and research
• The IEEE 802.15.3a task group gathered differentUWB characterisation attempts and proposed theIEEE UWB channel model
• The IEEE UWB channel model can berepresented by
h(t) = X
L∑l=0
K∑k=0
αk,lδ(t − Tl − τk,l) (1)
A New UWB Dual Pulse Transmission and Detection Technique – p.6/31
Sample of the IEEE channel model
0 50 100 150 200 250 300−0.2
−0.15
−0.1
−0.05
0
0.05
0.1
0.15
0.2
Time (ns)
Cha
nnel
Am
plitu
de
A New UWB Dual Pulse Transmission and Detection Technique – p.7/31
The Transmitted Reference (TR)System
• A coherent rake receiver must estimate thechannel tap gains and tap delays.
• The shape of a UWB pulse may be altered afterpassing through the channel.
• The TR system uses a doublet
Td=T
f
Td=T
f
2Tf
2Tf
Binary PAM b=1
Binary PAM b=−1
A New UWB Dual Pulse Transmission and Detection Technique – p.8/31
TR System (con’t)
The autocorrelation receiver uses the reference pulseto demodulate the data pulse.
Output of the autocorrelator is represented as
D =
Ns−1∑j=0
∫ (2j+1)Tf +Ttr
(2j+1)Tf
ri(t)ri(t − Tf )dt (2)
A New UWB Dual Pulse Transmission and Detection Technique – p.9/31
The Novel Dual Pulse (DP) System
• The DP system transmits a reference sub-pulsefollowed by a data sub-pulse as one pulse unit.
• The binary PAM modulated DP pulse isrepresented as
gdp(t) = p(t) + b · p(t −Tw
2), 0 ≤ t ≤ Tw (3)
• The DP system requires only one time frame totransmit a data pulse, effectively doubles thetranmission rate when compared with the TRsystem.
A New UWB Dual Pulse Transmission and Detection Technique – p.10/31
Illustration of the DP pulse
OOK
Tf
Tf
b="1" "1"
b="1"
"−1"
"−1"
Binary PAM
A New UWB Dual Pulse Transmission and Detection Technique – p.11/31
DP System Receiver
• The receiver design for DP system can beillustrated as follows
• Where T (Dl) is the test function defined by thedifferent combining schemes• Generalized Selection Combining (GSC)
• Absolute Threshold GSC (AT-GSC)
• Normalised Threshold GSC (NT-GSC)
A New UWB Dual Pulse Transmission and Detection Technique – p.12/31
General Selection Combining (GSC)
• This method selects L largest |Dl|’s to form D
• The test function T (Dl),
T (Dl) =
8
<
:
Dl, if |Dl| ≥ |D(L)|0, if |Dl| < |D(L)|
(4)
• The conditional probability of error given by
P (e|α, τ) = P (D < 0|b = +1, α, τ) =1
2πj
Z c+j∞
c−j∞
ΦGSC(s)
sds (5)
A New UWB Dual Pulse Transmission and Detection Technique – p.13/31
GSC (con’t)
• Moment generating function (MGF) of GSC
ΦGSC(s) =
Lt−1X
i=0
Z ∞
−∞
fi(Di)esDi
X
all Ii
Y
l∈Ii
Ψl(s, Di)Y
l′ /∈Ii
l′ 6=i
[Fl′(|Di|)−Fl′(−|Di|)]dDi
(6)
where
Ψl(s, x) =1
2esµl+
σ2
l2
s2
"
erfc
|x| + (µl + σ2l s)√
2σl
!
+ erfc
|x| − (µl + σ2l s)√
2σl
!#
(7)
Ii ⊂ {0, 1, · · · , Lt − 1} − {i}
A New UWB Dual Pulse Transmission and Detection Technique – p.14/31
Effect of L on GSC
0 2 4 6 8 10 12 14 16 18
10−4
10−3
10−2
10−1
100
Average Eb/N
0 (dB)
Bit
Err
or P
roba
bilit
y
GSC (CM3) (Lt = 110, L = 10, N
p = 50)
GSC (CM3) (Lt = 110, L = 20, N
p = 50)
GSC (CM3) (Lt = 110, L = 30, N
p = 50)
GSC (CM3) (Lt = 110, L = 40, N
p = 50)
GSC (CM3) (Lt = 110, L = 60, N
p = 50)
GSC (CM3) (Lt = 110, L = 110, N
p = 50)
A New UWB Dual Pulse Transmission and Detection Technique – p.15/31
Absolute Threshold GSC (AT-GSC)
• This method combines Dl that has absolute valuegreater than Dth to form the decision variable
yl = T (Dl) =
8
<
:
Dl, if |Dl| ≥ Dth
0, if |Dl| < Dth
(8)
• The MGF of AT-GSC is presented by
ΦAT−GSC(s) =
Lt−1Y
l=0
Φyl(s) =
Lt−1Y
l=0
[Fl(Dth) − Fl(−Dth) + Ψl(s, Dth)]. (9)
A New UWB Dual Pulse Transmission and Detection Technique – p.16/31
Effect of Dth on AT-GSC
0 2 4 6 8 10 12 14 16 18
10−4
10−3
10−2
10−1
100
Average Eb/N
0 (dB)
Bit
Err
or P
roba
bilit
y
DP, AT−GSC (CM3) (Dth
= 5, Np = 50)
DP, AT−GSC (CM3) (Dth
= 3, Np = 50)
DP, AT−GSC (CM3) (Dth
= 1.5, Np = 50)
DP, AT−GSC (CM3) (Dth
= 1, Np = 50)
DP, AT−GSC (CM3) (Dth
= 0.6, Np = 50)
DP, AT−GSC (CM3) (Dth
= 0.1, Np = 50)
A New UWB Dual Pulse Transmission and Detection Technique – p.17/31
Normalised Threshold GSC (NT-GSC)
• Like the AT-GSC, NT-GSC selects Dl that has absolutevalue higher than threshold Dth = ηthDmax whereDmax = max|Dl|
T (Dl) =
8
<
:
Dl, if |Dl| ≥ ηthDmax
0, if |Dl| < ηthDmax
. (10)
A New UWB Dual Pulse Transmission and Detection Technique – p.18/31
NT-GSC (con’t)
• The MGF of NT-GSC is represented by
ΦNT−GSC(s) =
Lt−1X
i=0
Z ∞
−∞
fi(Di)esDi
×Lt−1Y
l=0l6=i
h
Ψ̃l(s, ηthDi, Di) + Fl(ηth|Di|) − Fl(−ηth|Di|)i
dDi
(11)
• whereΨ̃l(s, x, y) = Ψl(s, x) − Ψl(s, y) (12)
A New UWB Dual Pulse Transmission and Detection Technique – p.19/31
Effect of ηth on NT-GSC
0 2 4 6 8 10 12 14 16 18
10−4
10−3
10−2
10−1
100
Average Eb/N
0 (dB)
Bit
Err
or P
roba
bilit
y
DP, NT−GSC (CM3) (ηth
= 0.9, Np = 50)
DP, NT−GSC (CM3) (ηth
= 0.7, Np = 50)
DP, NT−GSC (CM3) (ηth
= 0.5, Np = 50)
DP, NT−GSC (CM3) (ηth
= 0.4, Np = 50)
DP, NT−GSC (CM3) (ηth
= 0.2, Np = 50)
DP, NT−GSC (CM3) (ηth
= 0.1, Np = 50)
A New UWB Dual Pulse Transmission and Detection Technique – p.20/31
Simple autocorrelation receiver forDP system
• Receiver of the DP system can also berepresented by a simple autocorrelator
• Decision variable given by
D =
Ns−1X
j=0
Z jTf + Tw2
+Tdp−int
jTf + Tw2
r(t)r(t − Tw
2)dt (13)
• The autocorrelation receiver design for the DPsystem is similar to the TR system receiver design,thus providing similar receiver complexity
A New UWB Dual Pulse Transmission and Detection Technique – p.21/31
Comparison between TR system andDP system, CM1
0 2 4 6 8 10 12 14 16 18 20 22
10−4
10−3
10−2
10−1
100
Average Eb/N
0 (dB)
Bit
Err
or P
roba
bilit
y
TR (Ttr=28ns, N
p=1)
DP, GSC (Lt=40, L=20, N
p=1)
DP, AT−GSC (Dth
=1.5, Np=1)
DP, NT−GSC (ηth
=0.1, Np=1)
DP, Int (Tdp−int
=28ns, Np=1)
TR (Ttr=28ns, N
p=50)
DP, GSC (Lt=40, L=20, N
p=50)
DP, AT−GSC (Dth
=0.1, Np=50)
DP, NT−GSC (ηth
=0.1, Np=50)
DP, Int (Tdp−int
=28ns, Np=50)
A New UWB Dual Pulse Transmission and Detection Technique – p.22/31
Comparison between TR system andDP system, CM4
0 2 4 6 8 10 12 14 16 18 20 22
10−4
10−3
10−2
10−1
100
Average Eb/N
0 (dB)
Bit
Err
or P
roba
bilit
y
TR (Ttr=126ns, N
p=1)
DP, GSC (Lt=180, L=100, N
p=1)
DP, AT−GSC (Dth
=1.5, Np=1)
DP, NT−GSC (ηth
=0.1, Np=1)
DP, Int (Tdp−int
=126ns, Np=1)
TR (Ttr=126ns, N
p=50)
DP, GSC (Lt=180, L=100, N
p=50)
DP, AT−GSC (Dth
=0.1, Np=50)
DP, NT−GSC (ηth
=0.1, Np=50)
DP, Int (Tdp−int
=126ns, Np=50)
A New UWB Dual Pulse Transmission and Detection Technique – p.23/31
The Improved DP (iDP)System
• The performance of DP system is worse than theTR system due to the interference between thereference pulse and the data pulse
• The iDP system is designed to eliminate theperformance degradation of the DP system
• The iDP system requires two pulse transmissionfor each data bit
• The iDP pulses are given by
g1(t) = p(t) + b1 · p(t − Tw
2), 0 ≤ t ≤ Tw
g2(t) = −p(t) + b1 · p(t − Tw
2), 0 ≤ t ≤ Tw. (14)
A New UWB Dual Pulse Transmission and Detection Technique – p.24/31
Illustration of the iDP signal
Binary PAM Ns=2 b=1
Binary PAM Ns=2 b=−1
Tf
Tf
g1(t) g
2(t)
g2(t) g
1(t)
A New UWB Dual Pulse Transmission and Detection Technique – p.25/31
iDP system receiver design
• The block diagram for iDP receiver design
• whereDl =
Z l Tw2
+Tw
l Tw2
+ Tw2
rref (t − Tw
2)rdat(t)dt. (15)
rref (t) = r1(t − Tf ) − r2(t)
rdat(t) = r1(t − Tf ) + r2(t)
A New UWB Dual Pulse Transmission and Detection Technique – p.26/31
Performance comparison betweenTR, DP and iDP systems, CM1
0 2 4 6 8 10 12 14 16 18
10−4
10−3
10−2
10−1
100
Average Eb/N
0 (dB)
Bit
Err
or P
roba
bilit
y
TR (Ttr=28ns, N
p=1)
DP, GSC (Lt=40, L=20, N
p=1)
DP, AT−GSC (Dth
=1.5, Np=1)
DP, NT−GSC (ηth
=0.1, Np=1)
DP, Int (Tdp−int
=28ns, Np=1)
TR (Ttr=28ns, N
p=50)
DP, GSC (Lt=40, L=20, N
p=50)
DP, AT−GSC (Dth
=0.1, Np=50)
DP, NT−GSC (ηth
=0.1, Np=50)
DP, Int (Tdp−int
=28ns, Np=50)
Ns=2
TR & improved DP
Ns=1
CM1
A New UWB Dual Pulse Transmission and Detection Technique – p.27/31
Performance comparison betweenTR, DP and iDP systems, CM4
0 2 4 6 8 10 12 14 16 18
10−4
10−3
10−2
10−1
100
Average Eb/N
0 (dB)
Bit
Err
or P
roba
bilit
y
TR (Ttr=126ns, N
p=1)
DP, GSC (Lt=180, L=100, N
p=1)
DP, AT−GSC (Dth
=1.5, Np=1)
DP, NT−GSC (ηth
=0.1, Np=1)
DP, Int (Tdp−int
=126ns, Np=1)
TR (Ttr=126ns, N
p=50)
DP, GSC (Lt=180, L=100, N
p=50)
DP, AT−GSC (Dth
=0.1, Np=50)
DP, NT−GSC (ηth
=0.1, Np=50)
DP, Int (Tdp−int
=126ns, Np=50)
CM4N
s=1
Ns=2
TR & improved DP
A New UWB Dual Pulse Transmission and Detection Technique – p.28/31
Effect of IPI, CM1
0 2 4 6 8 10 12 14 16 18
10−4
10−3
10−2
10−1
100
Average Eb/N
0 (dB)
Bit
Err
or P
roba
bilit
y
TR (Ttr=28ns, N
p=1)
DP, GSC (Lt=40, L=20, N
p=1)
DP, AT−GSC (Dth
=1.5, Np=1)
DP, NT−GSC (ηth
=0.1, Np=1)
DP, Int (Tdp−int
=28ns, Np=1)
TR (Ttr=28ns, N
p=50)
DP, GSC (Lt=40, L=20, N
p=50)
DP, AT−GSC (Dth
=0.1, Np=50)
DP, NT−GSC (ηth
=0.1, Np=50)
DP, Int (Tdp−int
=28ns, Np=50)
Grey Marker −> DP, Ns=2
Black Marker −> iDP, Ns=2
A New UWB Dual Pulse Transmission and Detection Technique – p.29/31
Effect of IPI, CM2
0 2 4 6 8 10 12 14 16 18
10−4
10−3
10−2
10−1
100
Average Eb/N
0 (dB)
Bit
Err
or P
roba
bilit
y
TR (Ttr=42ns, N
p=1)
DP, GSC (Lt=60, L=30, N
p=1)
DP, AT−GSC (Dth
=1.5, Np=1)
DP, NT−GSC (ηth
=0.1, Np=1)
DP, Int (Tdp−int
=42ns, Np=1)
TR (Ttr=42ns, N
p=50)
DP, GSC (Lt=60, L=30, N
p=50)
DP, AT−GSC (Dth
=0.1, Np=50)
DP, NT−GSC (ηth
=0.1, Np=50)
DP, Int (Tdp−int
=42ns, Np=50)
Grey Marker −> DP, Ns=2
Black Marker −> iDP, Ns=2
A New UWB Dual Pulse Transmission and Detection Technique – p.30/31
Thank you!
A New UWB Dual Pulse Transmission and Detection Technique – p.31/31