Bit Error Rate Analysis of Convolutionally Coded BICM with Specific Interleaver Structures
Được đăng lên bởi
leduonglongdt5bk
Số trang: 6 trang

Lượt xem: 158 lần

Lượt tải: 0 lần
Bit Error Rate Analysis of Convolutionally Coded BICM with Specific Interleaver Structures Yuta Hori and Hideki Ochiai Department of Electrical and Computer Engineering, Yokohama National University 795 Tokiwadai, Hodogaya, Yokohama, Kanagawa 2408501, Japan Email: horiyuutanf@ynu.jp, hideki@ynu.ac.jp Abstract— Bitinterleaved coded modulation (BICM) has found its application in various wireless communication systems due to its simplicity in the design of coding and modulation. In particular, the BICM combined with convolutional coding has been adopted by several recent standards due to its low complexity and low latency at the decoder side. The performance of the convolutionally coded BICM depends not only on the constraint length of the code but also significantly on the structure of the bit interleavers introduced mainly for the purpose of dispersing the correlated bits. To date, however, theoretical analysis of the performance that well captures its dependence on the interleaver structures has not been presented in conjunction with the convolutionally coded BICM due to its complexity in precise analysis. In this paper, we derive a tight approximate BER expression over AWGN channels to evaluate its performance for a given bit interleaver structure, and present a design guideline for an optimal interleaver structure with its performance over fading channels in mind. I. I NTRODUCTION Bitinterleaved coded modulation (BICM) [1], [2] has gained its popularity in wireless communications due to its simplicity in designing channel coding with highorder constellation modulation over fading channels. In fact, BICM is known to outperform the wellstudied trellis coded modulation (TCM) [3] in terms of cutoff rate and bit error rate (BER), and has been employed for several recent wireless standards such as a wireless LAN (e.g., IEEE 802.11ac). In general, the performance of the BICM with convolutional codes considerably depends on the structure of the bit interleavers, and those suitable for BICM system are investigated in [4], [5]. In the case of an additive white Gaussian noise (AWGN) channel, it has been revealed that the BICM even without any interleaver outperforms those with bit interleaving [6], and some theoretical insights have been obtained for this case [7]. However, the theoretical analysis that elucidates the difference in the interleaver structures in terms of its BER has not been well addressed over fading channels, especially in orthogonal fr...
Bit Error Rate Analysis of Convolutionally Coded
BICM with Speciﬁc Interleaver Structures
Yuta Hori and Hideki Ochiai
Department of Electrical and Computer Engineering, Yokohama National University
795 Tokiwadai, Hodogaya, Yokohama, Kanagawa 2408501, Japan
Email: horiyuutanf@ynu.jp, hideki@ynu.ac.jp
Abstract— Bitinterleaved coded modulation (BICM) has found
its application in various wireless communication systems due
to its simplicity in the design of coding and modulation. In
particular, the BICM combined with convolutional coding has
been adopted by several recent standards due to its low com
plexity and low latency at the decoder side. The performance
of the convolutionally coded BICM depends not only on the
constraint length of the code but also signiﬁcantly on the structure
of the bit interleavers introduced mainly for the purpose of
dispersing the correlated bits. To date, however, theoretical
analysis of the performance that well captures its dependence on
the interleaver structures has not been presented in conjunction
with the convolutionally coded BICM due to its complexity in
precise analysis. In this paper, we derive a tight approximate BER
expression over AWGN channels to evaluate its performance for
a given bit interleaver structure, and present a design guideline
for an optimal interleaver structure with its performance over
fading channels in mind.
I. INTRODUCTION
Bitinterleaved coded modulation (BICM) [1], [2] has
gained its popularity in wireless communications due to its
simplicity in designing channel coding with highorder con
stellation modulation over fading channels. In fact, BICM is
known to outperform the wellstudied trellis coded modulation
(TCM) [3] in terms of cutoff rate and bit error rate (BER),
and has been employed for several recent wireless standards
such as a wireless LAN (e.g., IEEE 802.11ac).
In general, the performance of the BICM with convolutional
codes considerably depends on the structure of the bit inter
leavers, and those suitable for BICM system are investigated
in [4], [5]. In the case of an additive white Gaussian noise
(AWGN) channel, it has been revealed that the BICM even
without any interleaver outperforms those with bit interleaving
[6], and some theoretical insights have been obtained for this
case [7]. However, the theoretical analysis that elucidates the
difference in the interleaver structures in terms of its BER
has not been well addressed over fading channels, especially in
orthogonal frequencydivision multiplexing (OFDM) scenario.
Therefore, our goal is to derive a BER expression that can
be used for evaluating the performance difference provided by
particular interleaver structures and to present a design guide
line for an optimal interleaver in the framework of BICM
OFDM system over a frequencyselective fading channel, and
this paper provides its ﬁrst step toward this goal; we will
address deriving a BER expression for speciﬁc interleavers
and present design guideline for an optimal interleaver over
ENC
DEC
MOD
DEM
+
n
Fig. 1. Block diagram and notations of the BICM system.
an AWGN channel. Finally, we will demonstrate through
computer simulations that our design guideline can be also
valid for frequencyselective fading channels.
II. SYSTEM MODEL
The BICM system model and the notations used throughout
this paper are shown in Fig. 1. At the transmitter, a binary
information sequence of length N/n
c
, denoted by u =
[u
1
, ··· , u
N/n
c
], is fed to the binary convolutional encoder
(ENC) of rate r
c
= 1/n
c
and constraint length K
c
with
optimum distance spectrum, and the resulting codeword of
length N is given by c = [c
1
, ··· , c
N
]. It is then permuted by a
bit interleaver Π and the interleaved sequence is denoted by c
.
The modulator (MOD) maps the interleaved sequence c
onto
pulseamplitude modulation (PAM) symbols with constellation
size of M labeled by Gray labeling. We denote the set of M
PAM symbols by X and m = log
2
M as the number of bits
constituting one PAM symbol. Thus, the transmitted symbol
sequence can be expressed as x = [x
1
, ··· , x
K
] ∈ X
K
, and
K = N/m is the number of symbols per codeword. Note that
we consider the lowlatency scenario, where one codeword is
mapped onto exactly K consecutive PAM symbols (that may
be further placed on one OFDM symbol in the case of the
BICMOFDM system).
Let N
c
= {1, 2, ··· , N}, N
b
= {1, 2 , ··· , m}, and N
s
=
{1, 2, ··· , K} denote the sets of the indices for the coded
bits, the possible bit positions of MPAM, and the transmitted
symbols, respectively. The bit interleaver can be considered as
a onetoone reordering mapping:
M : n → (k, i), (1)
Để xem tài liệu đầy đủ. Xin vui lòng
Đăng nhập
Nếu xem trực tuyến bị lỗi, bạn có thể tải về máy để xem.
Bit Error Rate Analysis of Convolutionally Coded BICM with Specific Interleaver Structures

Người đăng:
leduonglongdt5bk
5
Tài liệu rất hay!
Được đăng lên bởi
gmtbv

1 giờ trước
Đúng là cái mình đang tìm. Rất hay và bổ ích. Cảm ơn bạn!
6
Vietnamese
Bit Error Rate Analysis of Convolutionally Coded BICM with Specific Interleaver Structures
9
10
744