A High-Rate Low-PAPR Multicarrier Spread Spectrum System Using Cyclic Shift Orthogonal Keying

Liao

Lin

2011

Int J Communication

SUMMARYIn this paper, a low-complexity spread spectrum system with M-ary cyclic-shift keying (MCSK) symbol spreading is proposed. In addition, by using the minimum-shift-keying (MSK) as the chip-level modulation, we obtain a high-rate QPSK-MCSK transceiver scheme which not only provides a constant-envelop and continuous-phase transmitted signal, but can also achieve a better performance than the conventional direct sequence spread spectrum (DSSS) system. At the transmitter, the data stream is first mapped into QPSK-MCSK symbols in terms of orthogonal Gold code sequences, then followed by the cyclic prefix (CP) insertion for combating the interblock interference, and finally applying the MSK scheme to maintain the constant-envelope property. The receiver first performs MSK demodulation, then CP removal, and finally the channel-included MCSK despreading and symbol demapping. Furthermore, the single input single output (SISO) QPSK-MCSK transceiver can be easily extended to the multiple input single output (MISO) case by incorporating the space-time block coding for high-link quality. Simulation results show that the proposed SISO and MISO QPSK-MCSK systems significantly outperform the conventional DSSS counterparts under the AWGN channel, and attain a more robust performance under the multipath fading channel.

Section: Mcsk Despreading and Qpsk-mcsk Decisionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 98%

A low‐complexity MSK‐based M‐ary cyclic‐shift keying transceiver for direct sequence spread spectrum system over multipath fading channels

Liao

Lin

2011

Int J Communication

“…Similarly, another differential decoding scheme can be obtained by applying the zero-forcing (ZF) technique to (8), resulting in…”

Section: Differential Mpsk-fsok Mc-ss Receivermentioning

confidence: 99%

A Low-PAPR Differential Frequency Shift Orthogonal Keying Transceiver for Multi-Carrier Spread Spectrum System over High Mobility Multipath Channels

Hwang

Liao

2010

Wireless Pers Commun

A new differential transceiver with a frequency-shift orthogonal keying (FSOK) technique is proposed for the multi-carrier spread spectrum (MC-SS) system over high mobility multipath fading channels. The design of the transceiver involves the following stages. First, the data stream is mapped into MPSK-FSOK symbols and spreaded by the frequencyshift orthogonal sequences. Second, the differential block encoder is exploited to combat the mobile channels. The Chu sequence is adapted for initial differential encoding, making the post-IFFT transmit signals with a low peak-to-average power ratio. Next, for the receiver, the maximum ratio combining technique is used for the block-based differential frequency-domain equalizer, which can overcome the multipath fading channel effect without requiring channel estimation. Finally, an efficient maximum likelihood despreading and demapping scheme is used to detect the modulation symbols. Furthermore, the differential MC-SS transceiver can be easily re-configured for a MISO differential MC-SS system with high link quality. Simulation results show that, under high mobility multipath channels, the proposed SISO differential MC-SS system can outperform the conventional MC-SS system. The proposed MISO differential MC-SS system with space-time diversity gain and M-ary modulation gain also exhibits excellent performance.Keywords Multi-carrier spread spectrum · Frequency-shift orthogonal keying · Peak-to-average power ratio

“…Next, the ith QPSK-FSOK symbol with (R + 2) bits of the pth substream of the kth user can be detected by the ML algorithm in [11]. Therefore, for the first R bits, the maximizing index of the despread data x k m,p (i) can be found bŷ…”

Section: Development Of Parallel Fsok Mc-cdma Receivermentioning

confidence: 99%

“…To eliminate MAI interference, Adachi and Nakagawa [9] have recently proposed a new MC-CDMA system using a conventional spreading code with user-specific phase rotated spreading codes, which can achieve multiple access communications. To overcome the MPI and MAI problems, we continue the work started in [10,11] and propose a novel extension called the parallel FSOK MC-CDMA system to support robust multiuser uplink communications over multipath channels while preserving the low-PAPR property. The development of the transceiver involves the following steps.…”

Section: Introductionmentioning

confidence: 99%

Novel low-PAPR parallel FSOK transceiver design for MC-CDMA system over multipath fading channels

Hwang

2011

J Wireless Com Network

A low peak-to-average power ratio (PAPR) transceiver using a new parallel frequency-shift orthogonal keying (FSOK) technique is proposed for the multiuser uplink multi-carrier CDMA (MC-CDMA) system over multipath fading channels. By employing the frequency modulated and multiplexed FSOK techniques to combat the multiuser and parallel substream interferences, respectively, the system retains a low-PAPR transmitted signal and a low-complexity equalizer without any matrix inversion. At the basestation, a multiuser receiver is derived, which involves parallel FSOK despreading, demapping, and maximum likelihood decision rule to acquire M-ary modulation gain and frequency diversity gain. For higher link quality, a multiple input single output FSOK uplink system can flexibly be configured. Simulation results are included to demonstrate that the proposed system achieves the low-PAPR property, space-frequency diversity, and M-ary modulation gain. Compared to the existing MC-CDMA and SC-FDMA systems, the proposed system exhibits significant performance superiority.Keywords: multi-carrier CDMA (MC-CDMA), frequency-shift orthogonal keying (FSOK), peak-to-average power ratio (PAPR), multiple input multiple output (MIMO), SC-FDMA