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A constant amplitude coding for orthogonal multi-code CDMA systems

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES 1997年第12期E80A卷 2477-2484页

作者： Wada, T Yamazato, T Katayama, M Ogawa, A Nagoya Univ Sch Engn Dept Informat Elect Nagoya Aichi 46401 Japan

In this paper, we present orthogonal multi-code CDMA systems with the constant amplitude transmission. In general, the dynamic range of the amplitude of the transmitting signal is very large in the case of orthogonal multi-code CDMA systems. In order to realize the constant amplitude transmission for orthogonal multi-code CDMA systems, we propose a constant amplitude coding. First, we show the basic concept of the constant amplitude coding. And then, we show that the constant amplitude transmission can be realized by the combination of the conventional orthogonal multi-code CDMA and the constant amplitude coding. Finally, the effectiveness of the proposed method is evaluated in terms of the bit error rate performance and it is shown that the proposed method is robust to the non-linear distortion caused by a high power amplifier (HPA).

关键词： orthogonal multi-code CDMA systems constant amplitude coding Hadamard code sequences non-linear amplifier

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Error correcting capability of constant amplitude coding for orthogonal multi-code CDMA systems

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IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES 1998年第10期E81A卷 2166-2169页

作者： Wada, T Yamazato, T Katayama, M Ogawa, A Nagoya Univ Sch Engn Dept Informat Elect Nagoya Aichi 4648603 Japan

In this paper, we discuss the error correcting capability of the constant amplitude coding. In orthogonal multicode CDMA systems, the transmitted signal has large amplitude fluctuation and the amplitude fluctuation causes large nonlinear distortion. In order to avoid the amplitude fluctuation, we have proposed "constant amplitude coding" in our previous study. The constant amplitude coding can achieve constant amplitude transmission by utilizing the redundancy of the coding, i.e., the coding can have an error correcting effect. In this paper, we examine the effectiveness of the error correcting capability of the constant amplitude coding and show that the constant amplitude coding is very effective against nonlinear distortion under the consideration of the error correcting capability.

关键词： orthogonal multi-code CDMA systems constant amplitude coding nonlinear distortion error correcting capability

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Design of a novel multi-dimensional HCOC multi-code spread spectrum system using pre-coding technique for high speed data transmission of DS-CDMA

Design of a novel multi-dimensional HCOC multi-code spread s...

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1st International Forum on Strategic Technology (IFOST 2006)

作者： Kong, Hyung Yun Lee, Dong Un Univ Ulsan Dept Elect Engn San 29Mugeo 2 Dong Ulsan 680749 South Korea

ISBN: (纸本)9781424404261

Recently, Me (Multi-code) modulation/demodulation (modem) technique has been explored for the high speed data transmission in wireless environment. The conventional Me modem can generate some side effects such as allocating Walsh codes, which motivates the researchers in [1] to propose a novel Me modem method with sub-code. But this proposed system should expand the size of sub-code to provide high-rate data transmission, which also affect adversely the performance of the system with high PAPR (Peak to Average Power Ratio). Thus, in this paper, we propose a novel pre-coded Multi-Dimensional HCOC (High Capacity Orthogonal Code) Me modem technique to reduce the high PAPR, which enables the performance improvement. This proposed system can be easily designed by concatenating HCOC Me modem with the generic Me modem. The pre-coding technique that is used in this paper is called CAC (constant amplitude coding) helps the system maintain the constant transmission power and reduce the maximum transmission power.

关键词： multidimensional HCOC multi-code constant amplitude coding DS-CDMA

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constant amplitude Encoders and Decoders with Error Correction (EC) for CDMA Systems

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IEICE TRANSACTIONS ON COMMUNICATIONS 2013年第8期E96B卷 2131-2138页

作者： Kim, Suil Bae, Sukneung Kim, Junghwan Univ Sci & Technol Hefei Peoples R China Univ Toledo Toledo OH 43606 USA

Multicode CDMA systems convert a high-rate serial data stream into low-rate parallel data streams prior to transmission, but reducing the peak-to-average-power-ratio (PAPR) is a prerequisite. In this paper, we propose constant amplitude coding schemes with forward error correction (EC) capability. The proposed schemes overcome the adverse nonlinear effects of the high power amplifier (HPA) by using the transmitted signal of constant amplitude and parity channel. In the first scheme, we add the EC capability to the previously reported constant-amplitude rate 4/4 (Suil's) scheme, which can transmit data without energy loss. Next, we propose a rate 12/16 decoder with EC capability, which is slightly different from the previous work through the addition of EC capability. Lastly, we propose a new high-rate EC capable 16/16 scheme without energy loss, which makes it superior to the conventional 12/16 scheme which experiences excessive energy loss due to redundancy. Computer simulation results confirm that new 4/4 decoder along with 12/16 decoder and 16/16 encoder/decoder can effectively reduce the inherent problem of high PAPR in the multicode CDMA signal transmission. Our methods also yield better BER performance than other constant amplitude coding-schemes.

关键词： constant amplitude coding multicode CDMA PAPR

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