JAIST Repository: BICM-ID-based IDMA over Multipath Fading Channels

Japan Advanced Institute of Science and Technology

JAIST Repository

https://dspace.jaist.ac.jp/

Title

BICM-ID-based IDMA over Multipath Fading Channels

Author(s)

WU, Kun; Anwar, Khoirul; Matsumoto, Tad

Citation

電子情報通信学会総合大会講演論文集, 2014年_通信

(2): 294-294

Issue Date

2014-03

Type

Conference Paper

Text version

publisher

URL

http://hdl.handle.net/10119/12341

Rights

Copyright (C) 2014 The Institute of Electronics,

Information and Communication Engineers (IEICE).

Kun WU, Khoirul Anwar and Tad Matsumoto, 電子情報

通信学会総合大会講演論文集, 2014年_通信(2), 2014,

294-294.

BICM-ID-based IDMA over Multipath Fading Channels

Kun WU1_{, Khoirul Anwar}1 _{and Tad Matsumoto}1,2 1

Information Theory and Signal Processing Lab, School of Information Science,

Japan Advanced Institute of Science and Technology (JAIST) 1-1 Asahidai, Nomi-shi, Ishikawa, 923-1292 Japan E-mail:{kunwu, anwar-k, matumoto}@jaist.ac.jp

2_{Centre for Wireless Communications (CWC), University of Oulu, 90014 Finland}

E-mail: [email protected]

Abstract—We proposed a detection scheme for Bit Interleaved Coded

Modulation with Iterative Detection-based Interleave Division Multiple Access system in fading channels by combinning with turbo equalizer, in which the codes are also effective in achieving excellent performance, the achieved frame error rate is only 0.5 dB away from the outage probability. In order to deeply elaborate the proposed system, in this paper we use extrinsic information transfer chart analysis combined with Matlab simulation results.

I. INTRODUCTION

The Interleave Division Multiple Access (IDMA) concept well exploits the advantageous characteristic of using very low rate codes where the informantion sequence to be transmitted is encoded by an iteratively decodable low rate code. However, designing such low rate code has been a bottle neck in utilizing IDMA in practical systems. Furthermore, in multipath fading channels, a good frame error rate (FER) performance can be achieved using turbo equalizer. In this paper, we firstly focus on code design by using extrinsic in-formantion transfer (EXIT) constrained binary switching algorithm (EBSA) [1]. Then, we move on to the concept of combined turbo equalizer. After that we evaluate the performance by simulation results.

II. SYSTEMMODEL

The transmission structure for Bit Interleaved Coded Modulation with Iterative Detection (BICM-ID)-based IDMA, is shown in Fig. 1. Each user uses the same BICM-ID structure, where the encoder is Single Parity Check Code and Irregular Repetition Code (SPC-IrR) [2]. The encoded bit sequence is bit-interleaved by a random interleaver Πk, and then accumulated by doped accumulator (DACC) with a switching ratio p to generate a new bits sequence

um,j, where j is the timing index at the output of DACC. The DACC output binary sequence uk,j are serial-to-parallel converted, and mapped on to a 4-QAM signal point, and in part, according to the non-Gray labeling pattern to produce transmission symbols xm at the timing index m, with modulation mixing ratio D.

At the receiver part, as shown in Fig. 2. Each user is detected independently, and then through the turbo equalizer, the inter-symbol interference (ISI) from the other users is cancelled by the soft cancellation iteration by iteration until it is fully eliminated. After that, hard decision is made before output.

III. EXIT ANALYSIS ANDSIMULATIONRESULTS

EBSA makes it easier to design suitable low rate code, from Fig. 3(a), very good match between the EXIT charts of demapper and decoder can be observed. It is one of the important reasons why the codes are effective in achieving excellent performance.

The FER performance is shown in Fig. 3(b), it can be observed that single user’s performance is close to the theoretical outage prob-ability, only about 0.5 dB gap exists. Meanwhile, the peformance of 8-user is close to the single user’s case, also roughly 0.5 dB gap exists. SPC IrR ς1 SPC IrR ςM ܾଵǡ௜ ܾெǡ௜ EM EM ݆݉݋݀݌ ് Ͳ ݆݉݋݀݌ ് Ͳ ܦܣܥܥ ܦܣܥܥ ߤଵǡ௝ ߤெǡ௝ ݔଵ ݔெ

Fig. 1. Transmission Structure

Global loop െ SC -M M SE T ur bo Eq ua liz er SPC-1 IrR-1 ܾ෠ ଵǡ௜ Soft-Symbol Generator ܮଵǡ௔ǡௗ௘௖ǡ௝ ܮଵǡ௘ǡௗ௘௖ǡ௝ _{ܮ෠ ଵǡ௣} ς1-ͳ + - ACC-1 SPC-1 IrR-1 ܾ෠ ெǡ௜ ܮெǡ௔ǡௗ௘௖ǡ௝ ܮெǡ௘ǡௗ௘௖ǡ௝ _ܮ෠ ெǡ௣ ςM-ͳ - ACC-1 + m r M P 1 P ܮଵǡௗ௔௖௖ǡ௝ ܮெǡௗ௔௖௖ǡ௝

Fig. 2. Receiver Structure

IV. CONCLUSIONS

We have evaluated performance of BICM-ID-based IDMA com-bined with turbo equalizer in multipath fading channels. We found that the excellent performance can be obtained by using very low rate code.

REFERENCES

[1] K. Fukawa, S. Ormsub, A. Tolli, K. Anwar, and T. Matsumoto, “EXIT-constrained BICM-ID design using extended mapping,” EURASIP

Jour-nal on Wireless Comm. and Networking, vol. 2012, no. 1, Feb. 2012.

[2] K. Fukawa, D. Zhao, A. Tlli, and T. Matsumoto, “Irregular repetition and single parity check coded BICM-ID using extended mapping -optimal node degree allocation,” in 2010 5th International ICST Conference

on Communications and Networking in China (CHINACOM), Beijing,

August 2010, pp. 1–6. 0 0.2 0.4 0.6 0.8 1 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 IA(dem)/IE(dec) IE(dem)/IA(dec) 4−QAM l

map=4 p=20 D=0.01 Optimized with EBSA

d_c=3 d_v=[2 14 15 100] a=[0.04 0.23 0.68 0.005]

Optimized with EBSA

(a) −8 −7 −6 −5 −4 −3 −2 −1 10−4 10−3 10−2 10−1 100 Average SNR Average FER 8−user, 6−path Single−user, 6−path Single−user, 6−path Outage Probability

(b) Fig. 3. EXIT Chart and FER

2014 年　電子情報通信学会総合大会

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