
L. L. CHEN, Z. DOU
164
Second, for the validity, the transmission rate of the
two systems is compared. When the operating frequency
occupied the entire 7.5 GHz band, the single-band PSWF
pulse duration 1, multiband PSWF pulse dura-
tion 2. Therefore, if other conditions are the
same, the pulse repetition period 12 2
4
m
Tn
ns s
4
m
T
sshm
.
Suppose the transmission rate of single-band UWB is
1b, and the transmission rate of MB-IR-UWB is ,
we can see that
TT NNT
2b
RR
112 2
1/, (1/ )
bssb ss
RNTR NTN sub
Therefore, theoretically in equal time, compared with
single-band UWB, the multi-band scheme can increase
the transmission rate by N times. Thus, multi-band UWB
communications technology plays an important role in
satisfying the increasingly high data transmission rate.
4.2. The Impact of Pulse Duration on System
Performance
Due to the advantage of PSWF’s high energy concentra-
tion, it is of great significance to increase the transmis-
sion rate as much as possible. From the analysis above,
we can conclude that the pulse duration affects the data
transmission rate indirectly. The following part will fo-
cus on the analysis of the effect of different m on sys-
tem performance. In the simulation, the number of pulse
per bit , the cardinality of the TH code
T
5
s
N3
h
N
.
The corresponding relation between different values
and is shown as Table 1. m
T
b
It can be seen from Figure 5 that the BER curves are
very close when m equals to 8ns, 4ns, 2ns.Under this
circumstance, the system performance is the best. When
m is 1.5ns, the system performance deteriorates seri-
ously, and when m
T is 1ns, the system performance
becomes worst. It is because that the larger m is, the
higher energy concentration of pulse in particular fre-
quency band is. So the less energy loss is, the better the
system performance is. Thus, the validity and reliability
is a pair of mutually contradictory unity. To improve the
reliability of the system, it would inevitably lead to a
decline in the validity. In our simulation, in order to en-
sure the system performance, the pulse duration which
corresponds to = 66.7 Mbps is the best, i.e. = 2
ns.
R
T
b
T
T
TR m
5. Conclusions
This paper takes the MB-IR-UWB communication system
Table 1. Corresponding relation between different Tm val-
ues and Rb.
Pulse duration Tm/ns 8 4 2 1.5 1
Bit rate Rb/Mbps 16.7 33.3 66.7 88.9 133.3
02468 10
10
-4
10
-3
10
-2
10
-1
10
0
Eb/N0(dB)
BER
R b= 16.7 M bit /s
R b= 33.3 M bit /s
R b= 66.7 M bit /s
R b= 88.9 M bit /s
R b =1 33 .3 Mb it/s
Figure 5. The performance comparison in different data
rate.
based on PSWF pulse as the research object, proposes a
new way of multi-band spectrum arrangement and uses
coherent demodulation method to achieve the best recep-
tion. Through system model building and simulation
analysis, we draw the conclusion that MB-IR- UWB
system has the same bit error rate performance with sin-
gle-band UWB. But in the MB-IR-UWB, the data can b e
transmitted in parallel, which can improve the transmis-
sion rate of information. In addition, PSWF pulse dura-
tion affects the BER performan ce. The simulation results
show that the shorter PSWF pulse duration is, the larger
the transmission rate is, but the system performance be-
comes worse. Therefore, in actual communication, we
should make a tradeoff between the validity and reliabil-
ity to a best choice.
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