Noise-Like Communication System Simulation Based on Simplex Codes Ensembles


Аuthors

Kuznetsov V. S.*, Volkov A. S.**, Solodkov A. V.***, Soroka V. G.****

National Research University of Electronic Technology, 1, sq. Shokina, Moscow, Zelenograd, 124498, Russia

*e-mail: vitaliy_kuznetsov@hotmail.com
**e-mail: leshvol@mail.ru
***e-mail: solodkov_aw@mail.ru
****e-mail: altair08111994@yandex.ru

Abstract

This article describes a mathematical model of a communication system based on selected signals and architectural solutions. This allows for statistical numerical modeling of both the reference channel with additive white Gaussian noise and real channels selected under conditions. An overview of methods for improving the reception characteristics of noise-like signals and the use of noise-resistant coding methods is given. The issues of creating a system prototype, software development methodology for heterogeneous systems, and debugging and testing of the end device were touched upon. Characteristic of a broadband signal system is being described as stealth, methods for its determining, and an example of calculation for the created communication system.

Communication systems with broadband (or noise-like) signals attract attention of specialists due to the combination of their characteristics such as their ability to operate in conditions of multipath propagation of radio signals, multiple access organizing, etc.

There is a problem herewith of power adjustment (a near-far problem), which is solved by centralized synchronous transmission in the downlink channel from the base station and adjusting the power of the subscriber station transmitters in the upstream channel to equalize the power at the receiving point. In the decentralized mode of operation without base stations, this problem has not been solved, especially at the possibility of subscribers’ mobility. In addition, a system with direct sequence spectrum expansion experiences significant degradation of performance when operating in asynchronous mode, i.e. at random time of transmission of pseudo-random sequences (PRS) in the ether. Communication system organizing possibilities in this case are determined by the cross-correlation properties of the used PRSs, which complicates significantly their search, and often generation and detection.

However, operation of multiple subscribers in the same band and in the same radio visibility zone can be organized by introducing an additional time division by introduction of the expanding PRS. With this, to increase the transmission rate, it is necessary to ensure signals transmission of from one subscriber to several at once, which can be guaranteed only due to the good correlation properties of the expanding ensemble. In this case, a timeslot is allocated to each subscriber in the personnel structure, which is set by a dedicated subscriber station, called a binding station, and a group of PRSs. Radiating to the air several PRSs simultaneously, the subscriber can transmit data to the address of several subscribers. With this, the PRSs discriminability at the reception is ensured by good characteristics of the employed expanding sequences, and the near-far problem does not arise due to the equal signal capacities for different subscribers with their principal equality at the transmission point.

Keywords:

communication systems, antinoise coding, communication systems prototyping, broadband signals

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