Does every bit need the same power? An investigation on unequal power allocation for irregular LDPC codes

Irregular LDPC codes can have capacity-approaching performance with an iterative BP decoder under AWGN channel with BPSK modulation. Generally in BPSK modulation, every bit within the block has the same power. In this paper, we investigate unequal power allocation (UPA) using BPSK modulation for irregular binary LDPC codes. We show that constant power modulation need not lead to the best performance. With UPA we see gains of up to 0.25dB, with larger gains possible if the receiver knows the details of the UPA scheme. Optimal power allocation is shown to depend strongly on the codes in use. Our work demonstrates the promise of the UPA scheme for some irregular LDPC codes.

[1]  Norbert Goertz,et al.  Source-adaptive power allocation for digital modulation , 2003, IEEE Communications Letters.

[2]  Yücel Altunbasak,et al.  An unequal error protection method for packet loss resilient 3D mesh transmission , 2002, Proceedings.Twenty-First Annual Joint Conference of the IEEE Computer and Communications Societies.

[3]  David Declercq,et al.  Enhancement of Unequal Error Protection Properties of LDPC Codes , 2007, EURASIP J. Wirel. Commun. Netw..

[4]  Ahmet M. Kondoz,et al.  Unequal power allocation for scalable video transmission over WiMAX , 2008, 2008 IEEE International Conference on Multimedia and Expo.

[5]  Mingyan Jiang,et al.  New research on unequal error protection (UEP) property of irregular LDPC codes , 2004, First IEEE Consumer Communications and Networking Conference, 2004. CCNC 2004..

[6]  Rüdiger L. Urbanke,et al.  Design of capacity-approaching irregular low-density parity-check codes , 2001, IEEE Trans. Inf. Theory.

[7]  P. Vary,et al.  Analysis of digital modulation with unequal power allocation , 2005, 2005 IEEE 61st Vehicular Technology Conference.

[8]  Dongfeng Yuan,et al.  Unequal Error Protected Image Transmission over Multilevel coded Wavelet Packet Multicarrier Modulation System , 2004, International Symposium onInformation Theory, 2004. ISIT 2004. Proceedings..

[9]  Daniel A. Spielman,et al.  Improved low-density parity-check codes using irregular graphs and belief propagation , 1998, Proceedings. 1998 IEEE International Symposium on Information Theory (Cat. No.98CH36252).

[10]  Robert W. Heath,et al.  Unequal Power Allocation for JPEG Transmission Over MIMO Systems , 2010, IEEE Transactions on Image Processing.

[11]  Sae-Young Chung,et al.  On the design of low-density parity-check codes within 0.0045 dB of the Shannon limit , 2001, IEEE Communications Letters.

[12]  Keang-Po Ho.  Unequal error protection based on OFDM and its application in digital audio transmission , 1998, IEEE GLOBECOM 1998 (Cat. NO. 98CH36250).

[13]  David J. C. MacKay,et al.  Comparison of constructions of irregular Gallager codes , 1999, IEEE Trans. Commun..

[14]  Amir K. Khandani,et al.  Unequal power allocation to the turbo-encoder output bits with application to CDMA systems , 1999, IEEE Trans. Commun..

[15]  Daniel A. Spielman,et al.  Efficient erasure correcting codes , 2001, IEEE Trans. Inf. Theory.

[16]  Balakrishnan Balamuralithara.  A New Unequal Power Allocation Scheme for Asymmetric Turbo Code System , 2009, Wirel. Pers. Commun..

[17]  Daniel J. Costello,et al.  LDPC block and convolutional codes based on circulant matrices , 2004, IEEE Transactions on Information Theory.

[18]  Peter Vary,et al.  BPSK modulation with unequal power allocation considering a priori knowledge , 2005, 2005 IEEE 16th International Symposium on Personal, Indoor and Mobile Radio Communications.