Orthogonal complementary codes for interference-free CDMA technologies

Over multipath channels, complete complementary code division multiple access (CC-CDMA) and convolutional spreading code division multiple access (CS-CDMA) provide inter-channel interference (ICI) free transmission with an enhanced spectral efficiency (SE). However, the convolutional spreading (CS) operation of the systems is computationally complex and involves a high peak-to-average power ratio (PAPR). To address such issues, we propose the concatenative complete complementary code (CCCC) division multiple access, named (CCC-CDMA). Since the CCCCs can be generated from the rows of the Walsh-Hadamard or discrete Fourier transform (DFT) matrices, the CS operation can be implemented using corresponding fast transforms (FTs) to reduce computational complexity. Simulation results show that the enlargement of the spreading factor (SF) strengthens the robustness against clipping noise. The binary CCCC generated by Walsh-Hadamard matrix exhibited excellent robustness against Doppler frequency shifts. Index Terms CDMA, complete complementary codes, zero correlation zone sequences, CC-CDMA, CS-CDMA I. INTRODUCTION To date, the generational changes of mobile communication technology have been primarily characterized by the adopted multiple access (MA) schemes. In the first generation, users have H. Mizuyoshi and C. Han was with the

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“…Appendix C, we proved that if we let E = E s m , then CS-CDMA provides the same relationship given in (16).…”

Section: B Review Of Cs-cdma [21]mentioning

confidence: 63%

“…The CC-and CS-CDMAs provide the same ICI-free input-output relationship and achieves higher SE than the DS-CDMAs employing Gold sequence, M-sequence, and Walsh sequence [16], [17], [35], [36]. When comparing the SEs of these two systems, CC-CDMA transmits KM symbols using packet of length…”

Section: The Comparison Of Cc-and Cs-cdmasmentioning

confidence: 99%

Concatenative Complete Complementary Code Division Multiple Access and Its Fast Transform

Mizuyoshi

Han

2023

IEEE Trans. Wireless Commun.

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“…where v [n] and r [n] denote the vectors containing the symbols transmitted by every user that spread its data on the nth chip and their corresponding effective received signature values, respectively. As can be seen from (16), based on the received chip y n and a priori input informationp n (v k ′ ,m ′ ), extrinsic values are calculated for all the constituent bits involved in (3). Substituting (17) and (18) into (16), the message update becomes…”

Section: Resultsmentioning

confidence: 99%

“…In the uplink transmission of CDMA, the number of users naturally exceeds that of available chips, which results in an overloaded condition. In that case, the orthogonality of spreading signatures cannot be maintained [2][3][4], thus the multiuser interference (MUI) becomes inevitable even if complicated multiuser detection (MUD) such as combination of minimum-mean-square error (MMSE) and parallel interference canceller (PIC) is adopted [5,6]. In order to deal with such problem, spreading codes under overload conditions have been designed [7][8][9], and low-density signature for un-coded CDMA (low-density signature code division multiple access -LDS-CDMA) has been proposed [10,11].…”

Section: Introductionmentioning

confidence: 99%

Joint sparse graph over GF( q ) for code division multiple access systems

Wen

2015

IET Communications

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“…This improves the processing gain but there is no effect on system capacity. The code scheme based on the complementary code was proposed in Chen et al (2006) to design a MAI-free CDMA system in a flat fading channel. These codes are derived from the sets of auto complementary codes, any two of which are cross complementary codes (Li and Huang, 2009).…”

Section: Introductionmentioning

confidence: 99%

Capacity enhancement of multicarrier code division multiple access (MCCDMA) using orthogonal complete complementary codes and adaptive constellations

Senthilkumar¹,

Amutha²

2014

Sci. Res. Essays

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The multicarrier code division multiple access (MCCDMA) is a strong candidate for the future wireless mobile communication systems put forth by service quality and system capacity. In order to exploit the maximum possible channel diversity and desirable correlation properties, the modification of MCCDMA system is addressed here to pave the way to remove the multiple access interference (MAI) effect and to increase the spectral efficiency (SE) due to the possible integration of space-time block coding (STBC) and multi input multi output (MIMO) techniques with two-dimensional orthogonal complete complementary (OCC) codes. The impact on modifications in the MCCDMA system is studied. Due to frequency selective fading and multipath effects, MCCDMA suffers from MAI due to loss of orthogonality among the users. In this paper, the constellation movement scheme is proposed to break the interference limitation in order to increase the SE and system capacity. In this scheme, the constellation of one of the users is moved adaptively relative to the other by an optimal angle based on quantized estimation to counteract MAI, caused by multipath effects without varying the transmit power in order to satisfy minimum distance threshold at the detectors. The simulation result shows that this modified MCCDMA system and proposed constellation movement scheme achieves significant performance improvement in terms of bit error rate (BER) and SE compared to conventional MCCDMA systems using unitary spreading codes. It also shows that the proposed scheme combats MAI against frequency selective fading and multipath effects and achieves a significant improvement in user capacity as the number of users increased.

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Orthogonal complementary codes for interference-free CDMA technologies

Cited by 56 publications

References 10 publications

Concatenative Complete Complementary Code Division Multiple Access and Its Fast Transform

Concatenative Complete Complementary Code Division Multiple Access and Its Fast Transform

Joint sparse graph over GF( q ) for code division multiple access systems

Capacity enhancement of multicarrier code division multiple access (MCCDMA) using orthogonal complete complementary codes and adaptive constellations

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