Effect Of Code Rate Research Articles

Effect of Coding and Diversity on the Performance of Wavelet Packets Multicarrier Multicode CDMA System

Coding and diversity are two techniques that can be used to improve communication system performance. The aim of this paper is to compare the effect of coding and diversity on the bit error rate performance of wavelet packets-multicarrier\multicode coded division multiple access system. Two different code rates have been considered, namely, R = 1/2 and R = 1/3. In addition, three types of diversity have been discussed, which are selection diversity, equal gain combining and maximum ratio combining. This study includes the effect of code rate, the number of substreams, the diversity order, the multipath intensity profile, the Nakagami parameter, and the number of uses. The study reveals that the code rate R=1/3 outperforms the code rate R=1/2. In addition, it has been noticed that the system with coding outperform the system with diversity when the channel interference is minimal, which includes less number of path, small Nakagami parameter, and a small number of users. The system with maximum ratio combining diversity in most conditions has the best performance.

Energy-efficient cooperative communication in wireless sensor networks using turbo codes

Energy efficiency is the main issue in the wireless sensor network. In this paper, we have developed the energy model for Virtual-Multiple Input Single Output cooperative communication using turbo codes. We have compared the energy consumption of uncoded cooperative communication with coded cooperative communication. The effect of code rate, number of participating nodes, channel conditions, target bit error rate on the energy consumption is also investigated. The simulation results show that significant energy saving can be obtained through the proposed turbo coded cooperative communication.

Performance Analysis of LDPC Coded SFH/BPSK in LFM Jamming

In this paper, we investigated the low density parity check (LDPC) coded performances of slow-frequency-hopped binary phase shift-keying (SFH/BPSK) systems in the presence linear frequency modulated (LFM) jamming. We investigated the effects of code rate, code length, the number of symbols per hop (SPH) and interleaver on the performance of the SFH/BPSK system with LFM jamming by numerical simulation. And the results suggest that there is good performance through designing the system reasonably.

Performance Analysis of LDPC Coded SFH/BPSK in Partial-Band Interference

In this paper, we investigated the low density parity check (LDPC) coded performances of slow-frequency-hopped binary phase shift-keying (SFH/BPSK) systems in the presence partial-band interference (PBI). The contributions of this paper are two folds. First, we give the bits error probability (BER) of the SFH/BPSK system with PBI by analysis, and further verify it by numerical results. Second, we investigated the effects of code rate, code length, the number of symbols per hop (SPH) and interleaver on the performance of the SFH/BPSK system with PBI by numerical simulation.

Performance Bounds of Optical Receivers With Electronic Detection and Decoding

In this paper, we investigate lower bounds of optical-signal-to-noise ratio (OSNR) for three types of electronic digital-signal-processing (DSP) receivers, which are used for an intensity-modulated and direct-photo-detected optical transmission link. Target is to determine the performance bound of this transmission link if equalization and/or forward error correction (FEC) are used. The investigated DSP methods are hard-input FEC decoding, soft-input FEC decoding, and sequence detection. The impact of chromatic and polarization mode dispersion, as well as the effect of code rate on the bounds, is shown. Signal statistics are computed analytically. Several implementations of coding and detection schemes, such as Reed-Solomon (RS) and low-density parity-check (LDPC) decoding as well as Turbo equalization, are investigated, and we show the distance of their performances to the derived bounds in quite some detail.

Adaptive Iterative Multiuser Decision Feedback Detection

Adaptive iterative receivers which combine multiuser decision-feedback detection with maximum a posteriori (MAP) decoding and soft feedback are presented for synchronous coded direct sequence-code-division multiple access. Both successive and parallel demodulation of users are considered. Optimal filters are derived using both minimum mean squared error and least squares (LS) criteria. The latter assumes short (repeated) spreading codes and that the users to be demodulated simultaneously transmit training sequences. The LS criterion does not require prior knowledge or estimates of spreading codes and channels. Simulation results show that the adaptive receiver can perform significantly better than the standard (soft) interference canceller, since the adaptive algorithm attempts to measure and exploit the second-order statistics between the input and output of the MAP decoder. With limited training, successive feedback and decoding performs significantly better than parallel feedback. The effect of code rate on performance is examined, and reduced-rank versions of the adaptive LS algorithms, which can reduce training overhead, are also presented.

Forward-link performance of satellite CDMA with linear interference suppression and one-step power control

Wideband direct-sequence (DS)-code-division multiple-access (CDMA) is a strong candidate for both terrestrial and satellite components of UMTS. The forward-link capacity of a satellite DS-CDMA system with a conventional matched filter (MF) receiver is limited by interference from adjacent beams and possibly overlapping beams from multiple satellites. In this paper, we study the performance of the linear minimum mean squared error (MMSE) receiver for the satellite forward link. System constraints are long propagation delay, which prevents accurate closed-loop power control, and low on-board power consumption, which implies a low received bit energy to noise density ratio at the mobile receiver. We consider a one-step power adjustment algorithm which attempts to compensate for random shadowing and path loss, and compare the associated performance of the MMSE and MF receivers. Dual-satellite diversity is also considered. The effect of code rate on performance is studied through the use of punctured convolutional codes and the evaluation of random coding bounds. Our results indicate that linear MMSE interference suppression can improve the quality of service and increase system capacity significantly.

Delay and throughput for three transmission schemes in packet radio networks

The results of a simulation of a fully connect packet communication network are presented. The network employs the slotted ALOHA channel access protocol, and Reed-Solomon coding is used to correct errors and erasures in the received packets. The network has a fixed number of channels available for packet transmissions. In two of the transmission schemes considered, a given packet transmission occurs on a single channel only. One of these employs fixed assignment of terminals to the channels, and the other employs random assignment. A third method permits each transmitter to hop randomly over the set of channels during the transmission of a packet. The terminal transmits on one channel at a time, and it transmits a fixed number of symbols during each dwell interval. Delay and throughput are evaluated for all three transmission methods. The effects of code rate on the performance of the channel-hopping scheme are explored, and the improvement that can be obtained for the channel-hopping scheme by use of incremental-redundancy transmission is examined.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>