In this letter, we propose an uplink sparse code-aided on-off division multiple access (SC-ODMA) system that enhances energy efficiency and error correction capabilities. In this SC-ODMA system, each user is assigned ...
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In this letter, we propose an uplink sparse code-aided on-off division multiple access (SC-ODMA) system that enhances energy efficiency and error correction capabilities. In this SC-ODMA system, each user is assigned a predetermined codebook containing M sparse codewords, integrating bit-to-sparse-code mapping and spreading. Specifically, the message of each user undergoes polar encoding and sparse code mapping, then is transmitted in a time-hopping manner based on user-specific on-off patterns. A key contribution of this letter is the integration of sparse code mapping with ODMA, significantly improving performance while maintaining energy efficiency. Simulation results indicate that the proposed SC-ODMA system notably improves energy efficiency and significantly reduces the block error rate (BLER) compared to traditional ODMA systems. Furthermore, the proposed scheme maintains competitive energy efficiency across various conditions, including coderates, user loads, and BLER targets, illustrating its robustness and adaptability in dynamic communication environments.
ra code, using BP iterative decoding algorithm for decoding in AWGN channel, is linear time encoding and decoding algorithm and its performance is closer to the Shannon limit. In order to improve decoding speed and re...
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ISBN:
(纸本)9783642252549
ra code, using BP iterative decoding algorithm for decoding in AWGN channel, is linear time encoding and decoding algorithm and its performance is closer to the Shannon limit. In order to improve decoding speed and reduce decoding complexity, this paper studies the simplified decoding algorithm of ra code, puts forward the minimal sum algorithm of ra code, and proposes the poly-line decoding algorithm based on BP algorithm. The simulation results show that error coderate of the system reduces and its performance closes to channel capacity with increasing message length. When the number of iterations increases, the error coderate drops with better system performance.
Aiming at reducing the system complexity, raising communication rate and supporting CDMA based applications, a direct sequence spread spectrum based underwater acoustic communication system is proposed. BPSK/QPSK modu...
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ISBN:
(纸本)9781424436927
Aiming at reducing the system complexity, raising communication rate and supporting CDMA based applications, a direct sequence spread spectrum based underwater acoustic communication system is proposed. BPSK/QPSK modulation is used. A ra coding scheme is adopted to reduce the BER. To reduce the phase-acquisition complexity of receiver, a carrier modulation method which lets spread-spectrum code and carrier have the same phase is adopted in transmitter. To raise the communication rate, an architecture of de-spreading, before demodulation is used in receiver. To support CDMA based applications, a band-pass signal acquisition strategy is used in receiver, and the acquisition method is delay correlation acquisition algorithm. Matlab-based simulations and practical system based experiments are carried out. The results show that the system has a good performance at supporting multi-user communication and rejecting multi-path effects. Under a water tank environment, the BER of the system without interference of other users is at 10(-4) order of magnitude, and the BER of the system with interference of two users is at 10(-3) order of magnitude.
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