Spread Spectrum Communication System
Performance Analysis based on the Complete
Complementary Sequence
Li Shufeng, Zhang Yuchi and Jin libiao
School of Information Engineering Communication University of China
Dingfuzhuang East street No.1, Chaoyang District, Beijing, China 10024
johninch@163.com
Abstract - The bit error rate (BER) performance of CDMA
system will rapidly deteriorate under the co-channel interferences. To
solve the problem, we give a polyphase complete complementary
sequence-based direct-sequence code-division multiple access (CC-
DS-CDMA) for additive white Gaussian noise (AWGN) channel in
this paper. Sets of sequences with complete complementary principle
are known because of their ability to achieve excellent correlation
properties. Different from the classical CDMA systems, we take the
quadri-phase complete complementary sequences (CC-S) for
example to do the performance simulation owing to polyphase CC-S
are superior to a single sequence in properties. We draw a conclusion
that using CC-S as spread spectrum code can suppress noise
interference more effectively and greatly reduce the interference
among different users in comparison to those conventional pseudo-
random(PN) sequence (such as m-sequence, gold-sequence) within
lots of simulation.
Keywords - complete complementary sequence, spread
spectrum communication, polyphase sequence, performance
simulation.
I. INTRODUCTION
The origin of complementary codes can be traced back to
half a century ago. The Golay first studied pairs of binary
complementary codes [1]. Then the properties of
complementary codes and their relation to other codes were
further investigated. One of quite remarkable contributions is
that Suehiro extended the concept to the generation of CC-S
families [2]. During the investigation of the latter applications,
researchers discovered the method of generalized
complementary sequence sets. A generalized complementary
set may contain more than two sequences. This notion
eliminates the constraint on the number of sequences in a set.
Those work paved the way for practical applications of CC-S
in modern CDMA systems. The CC-S are a collection of
sequence sets by extending the original complementary codes
with the ideal correlation property that the auto-correlation
function(ACF) must be zero for all possible shifts except the
zero shift and the cross-correlation function(CCF) sum
between each pair of distinct sequence sets is zero for all shifts
[3].the performance of DS-CDMA system relies on the
correlation properties of the employed spreading sequences,
and the full spectrum efficiency [4] is obtained only when
spread spectrum code achieved the ideal correlation
properties. However, there is no such a single sequence to
satisfy the ideal correlation, so the CC-S opens the new
direction for DS-CDMA system.
The CC-S has been applied in many fields. And there are
many attempts to apply it to the radar [5-7]. With the
continuous development of communication technology, there
are still many attempts to utilize CC-S in communication
technology [8-10].
As we all know , The properties of the transmitted signals
impact on the performance of systems directly .So the signals
needs to satisfy the ideal correlation function to suppress the
co-channel interference. Compared with binary sequences and
frequency coded sequences, the polyphase sequences have the
best ACF property. Therefore, we take the new quadri-phase
CC-S as spreading code to spread spectrum in the DS-CDMA
system in this paper.
The organization of this paper is as follows: Section 2
introduces the concept of the polyphase CC-S. And section
3 will provide the simulation flow chart, the simulation model
architecture based on CC-S and the performance analysis of
the specific algorithm. Section 4 displays the DS-CDMA
system simulation results based on the CC-S and other
conventional pseudo-random sequence. Then the superiority
of the CC-S in anti-interference performance is verified
through the simulation results. The last section makes a
summary of what we talked about and learned from the
simulation results.
II. THE CONCEPT OF THE POLYPHASE CC-S
First, supposing that
consisits of N pairs of
polyphase complete complementary sequence, the length of
them are L. And if
satisfy the following definition
equation that correlation function, then they can be called CC-
S [11]:
(i) For every i=1, 2..., N, it holds that
2 = 0
( ) ( )
0 0
i i i i
A A B B
L
RR
, (1)
(ii) For every 1≤ i, j≤ N , i≠j, it holds that
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