Bound Of Bit Error Probability Research Articles

Orthogonal Binary Modulation Division for Two-User Uplink Massive MIMO Systems With Noncoherent ML Detection

This letter considers a noncoherent two-user uplink system, where each user has a single antenna and a base station is equipped with a large number of antennas. It is assumed that small scale channel fading is Rayleigh fading and quasi-static in two consecutive time slots and changes to other values independently in the next block. For such massive MIMO uplink system, we propose an orthogonal binary modulation scheme and utilize a noncoherent maximum likelihood receiver rather than a commonly adopted channel orthogonality approximation to analyze its error performance. A fast decoding algorithm is obtained and an exact bit error probability (BEP) formula is derived. When the large scale fading coefficients are available at the transmitters, a closed-form optimal power loading is attained that minimizes a tight upper bound of BEP. Computer simulations demonstrate that in a mild signal-to-noise ratio region, the optimized upper bound is almost equal to the truly optimized BEP. Hence, our derived BEP formula can be used to quantify how many antennas we need for the given BEP. In addition, the extension of all these results to the system with coherence time longer than two is also briefly discussed.

Evaluation of Bit Error Probability for CPM MIMO Systems in Rayleigh Channel

Space time codes (STC) design employing continuous phase modulation (CPM) is well suitable for a multi-antenna system with low power and compact spectrum. Although STC design criteria for CPM MIMO system have been developed to date, the evaluation of performances with CPM MIMO system requires more general results like linear modulations such as PSK, QAM and so on. In this paper, Laurent decomposition is first applied and the conclusions of PAM signals in MIMO systems are extended to CPM MIMO systems. Thereby the average exact bound of bit error probability is derived. Further, space time block codes with CPM MIMO are introduced and its decoding is simplified for Monte-Carlo simulation. Finally, analytical and simulated results have confirmed the performances of CPM MIMO system.

Effect of filtering on the synchronization and performance of chaos-based secure communication over Rayleigh fading channel

Chaos synchronization is one of the main challenging issues involved in the development of wireless chaos-based secure communication (CBSC) due its crucial influence on the error performance and system reliability. This paper is concerned with the effect of filtering chaotic signals on the synchronization and error performance of CBSC schemes due to the finite bandwidth of realistic fading channel and/or signal detection necessities. The double scroll chaotic attractor is employed at the transmit and receive terminals as in a drive-response configuration with identical synchronization and a low pass filter model is utilized in this investigation. The upper bound of bit error probability considering Rayleigh fading channel and synchronization mean squared error is derived and evaluated for different values of filter parameter. Theoretical analysis and simulation results show that as the filter cut-off frequency decreased lower than the chaotic signal bandwidth, the synchronization error is considerably increased due to high distortion in the normal geometrical configuration of the attractor. As a result, the average bit-error-rate performance is degraded significantly with high possibility of link failure. Therefore, careful system design should be made to mitigate the filtering effects and achieve the essential synchronization of promising CBSC systems.

Enhanced Secure Error Correction Code Schemes in Time Reversal UWB Systems

In this paper, secure channel coding schemes based on turbo codes are suggested for time reversal ultra wideband (TR-UWB) systems. Turbo code has the capability of error correction near Shannon's limit. Adding security to turbo code is an attractive idea since it could reduce the overall processing cost of providing secure coded data and enjoys the advantages of high-speed encryption and decryption with high security, smaller encoder and decoder size and greater efficiency. The proposed turbo code schemes are labeled as follows: secure puncturing rate, secure frame length, and secure interleaving. Using these scenarios, secure turbo code is defined in a way that the redundant information used for error correction is not pre-determined by the nature of the error correction part of the algorithm but it can be chosen arbitrarily out of the whole set of possible strings. The lower bound of bit error probability for secure turbo code schemes in AWGN and TR-UWB systems are evaluated. Analytical and simulation results show secure turbo code performance is very satisfying. Various crypto-analytical attacks are investigated against these schemes. Based on this analysis, secure turbo code structures changed during the encryption procedure to increase the complexity of linear and differential cryptanalysis. It is seen that the performance of conventional turbo code and random frame length with Poisson distribution are the same. Comparing these schemes shows, secure interleaving approach has the best performance and secure puncturing rate the worst, but the latter provides the most security. The enhanced security of UWB, due to rich multipath nature of UWB channel, could be exploited. Due to space-time focusing property of time reversal UWB, there is an environmental confidentiality (or spatial security), which is additional security for secure turbo code in this system. Using secure turbo code, it is possible to increase the transmission range of UWB systems.