M-ary Direct Sequence Spread Spectrum Research Articles

TCN-based M-ary mobile spread spectrum underwater acoustic communication

A deep learning-based direct sequence spread spectrum (DSSS) underwater acoustic (UWA) communication system was proposed in this study to improve the performance of the conventional system under Doppler effects and low signal-to-noise ratio (SNR). The Temporal Convolutional Network (TCN) model was used as the receiver of the system. Simulation results showed that the TCN-based M-ary DSSS UWA communication system outperformed the conventional system under Doppler effects and complex shallow water acoustic channel. A transfertraining algorithm was used for fine-tuning of the model based on sea real-time data to achieve optimal performance. Sea experimental results showed that the fine-tuned TCN model improved the communication effect under Doppler background in the complex dynamic environment of shallow water.

Double-differential coded M-ary direct sequence spread spectrum for mobile underwater acoustic communication system

This paper presents a double-differential coded M-ary direct sequence spread spectrum (DD-MSS) underwater acoustic communication system to overcome problems of both low signal-to-noise ratio and severe Doppler effect. The system is very efficient in the challenging band-limited underwater acoustic channel and has many applications, particularly in which the transmitter and the receiver are mobile. Given that the bit error rate (BER) performance is unaffected, this scheme results in a significant improvement in the data rate compared to direct sequence spread spectrum (DSSS) communication systems. The MSS system uses M pseudo-random codes to represent k bits of information and offers advantages of a higher spectral efficiency and a lower energy consumption than the DSSS system. Both simulations and experiments are performed, and the results are discussed in the paper for the performance evaluation of the proposed scheme. The results demonstrate a better BER performance using the DD-MSS in a mobile environment.

The Bank of Matched Filters for an Optical ZCZ Code Using a Sylvester Type Hadamard Matrix

The optical ZCZ code is a set of pairs of binary and bi-phase sequences with zero correlation zone. An optical M-ary direct sequence spread spectrum (M-ary/DS-SS) system using this code can detect a desired sequence without interference of undesired sequences. However, the bank of matched filters in a receiver circuit may fall into large scale. In this paper, we propose the compact construction of a bank of matched filters for an M-ary/DS-SS system using an optical ZCZ code. This filter bank can decrease the number of 2-input adders from O(N2) to O(N) and delay circuits from O(N2) to O(N log2 N), respectively, and is implemented on a field programmable gate array (FPGA) corresponding to 400,000 logic gates.

An FPGA receiver for CPSK spread spectrum signaling

In this paper, we present the design, implementation and testing of an M-ary direct sequence spread spectrum receiver suitable for wireless home networking applications. The receiver employs a novel code-phase-shift keying (CPSK) signaling scheme, in which each of the M signaling waveforms is derived from a different phase shift of a single pseudonoise code sequence. The receiver consists of an IF demodulator and a CPSK baseband decoder, implemented using discrete components and an FPGA (field programmable gate array) chip, respectively. A modified double-dwell serial search scheme is used for code acquisition and tracking, and the carrier-phase synchronization is solved by a Costas loop in the IF demodulator and a double threshold detection scheme in the CPSK decoder. Measurements of receiver performance are presented and compared with theoretical calculations.

Design, Analysis, and DSP-Based Implementation of a Code-Phase-Shift Keying Receiver for Wireless Local Area Network Applications

This paper introduces code-phase-shift keying(CPSK), a novel M-ary direct-sequence spread-spectrum(DS-SS) signaling technique that is particularlysuitable for wireless local area network applications. In CPSK, each of the M signaling waveforms isobtained by a different code phase shift of a singlepseudonoise (PN) sequence. It increases the data ratewithout sacrificing spreading gain, and is more power efficient over additive white Gaussian noise(AWGN) than conventional DS-SS signaling methods. Thedesign, analysis, and implementation of a DSP-basedreceiver is presented to demonstrate the practicality of the signaling method. In our design, thereceived IF signal is downconverted into two quadraturebaseband components that are filtered and A/D convertedat 1 MHz into 8-bit samples for processing by three TMS320C40 processors. The tracking andacquisition schemes are adapted from conventional DS-SSreceivers, while the carrier-wave synchronizationproblem is solved by a novel technique calledphase-invariant reception. The design is tested in AWGN andsingle-tone interference environments. Implementationlosses and acquisition performances arequantified.

Comments on "Optimization of the Processing Gain of an M-ary Direct Sequence Spread Spectrum Communication System"

Comments on "Optimization of the Processing Gain of an M-ary Direct Sequence Spread Spectrum Communication System"

Correction to "Optimization of the processing gain of an M-ary direct sequence spread spectrum communication system"

Summary form only given, as follows. On page 1398 of the above paper (ibid., vol. COM-28,Part II,pp. 1389-1398, Aig. 1980), the Acknowledgment was published incorrectly. The correct Acknowledgment is as follows: "ACKNOWLEDGMENT The authors would like to thank Prof. C. Ziegler for generating the numerical results, and J. Bartow and S. Hall for their helpful suggestions."

Optimization of the Processing Gain of and M-ary Direct Sequence Spread Spectrum Communication System

In most realistic communication systems, be they spread spectrum or conventional systems, some overall bandwidth constraint is usually placed upon the system. In the case of spread spectrum communications, this constraint limits the amount of processing gain that the system can employ. In addition to processing gain, factors such as alphabet size affect the total bandwidth. It is the purpose of this paper to combine these two effects to determine how one should trade off the amount of processing gain one uses relative to the underlying modulation bandwidth when one is operating under the constraint of fixed total system bandwidth.