F. Askarian, Dr. S.m. Razavizadeh, Dr. F. Haddadi,
Volume 11, Issue 4 (12-2015)
Abstract
In this channel,we study rate region of a Gaussian two-way diamond channel which operates in half-duplex mode. In this channel, two transceiver (TR) nodes exchange their messages with the help of two relay nodes. We consider a special case of the Gaussian two-way diamond channels which is called Compute-and-Forward Multiple Access Channel (CF-MAC). In the CF-MAC, the TR nodes transmit their messages to the relay nodes which are followed by a simultaneous communication from the relay nodes to the TRs. Adopting rate splitting method in the terminal encoders and then using Compute-and-Forward (CF) relaying and decoding the sum of messages at the relay nodes, an achievable rate region for this channel is obtained. To this end, we use a superposition coding based on lattice codes. Using numerical results, we show that our proposed scheme has better performance than other similar methods and achieves a tighter gap to the outer bound.
H. Hamdoun, S. Nazir, J. A. Alzubi, P. Laskot, O. A. Alzubi,
Volume 17, Issue 3 (9-2021)
Abstract
High-Efficiency Video Coding (HEVC) is the latest video encoding standard that achieves much better compression efficiency compared to the earlier encoding standards. Satellite channels have a long round trip time (RTT) making it difficult to use packet acknowledgments. Real-time video streaming applications preclude such packet acknowledgments in satellite networks due to strict delay constraints. We propose a combined use of Turbo Coding (TC) and Network Coding (NC) techniques to achieve better video quality over the noisy satellite links using UDP at the transport layer. We evaluate the performance improvement of turbo network coding (TNC-UDP) over the traditional turbo-coded (TC-UDP) protocol for HEVC video streaming in satellite networks. The simulation results show that compared to TC-UDP, the proposed scheme achieves PSNR improvements ranging from 14-20 dB for poor channel conditions (1-2 dB) for the two selected video sequences.
Smita Jolania, Ravi Sindal,
Volume 20, Issue 1 (3-2024)
Abstract
Fifth Generation-New Radio (5G-NR) is an advanced air interface defined to fulfil diverse services with ubiquitous coverage in next generation Wireless networks. The waveform is the crucial part of air interface that must have good spectral confinement and low peak-to-average power ratio (PAPR). Orthogonal Frequency Division Multiplexing (OFDM) is a widely used air interface in Fourth Generation Long Term Evolution (4G-LTE) system. But OFDM suffers from high PAPR, Carrier Frequency offset (CFO), and loss of spectral efficiency due to insertion of cyclic prefix. So, the high dense networks with heterogeneous traffic in the 5G requires new multicarrier waveform. In the proposed work, waveforms based on sub-band filtering are considered due to more flexibility and shorter filter length as compared to the sub-carrier-based filtering waveforms. Two major 5G waveform candidates Filtered-Orthogonal Frequency Division Multiplexing (F-OFDM) and Universal Frequency Division Multiplexing (UFMC) are proposed in the system design. Channel coding is the inherent part of air interface for enhancing the error performance. New error correcting channel codes introduced in NR to support variable information block length and flexible codeword size. The capacity achieving Polar codes is the highlight of this paper adopted for control channels. 5G NR air interface using new modulation waveform along with the polar coding can be an effective way to enhance error performance. This paper presents comparative analysis of comprehensive systems Polar coded F-OFDM (PC-F-OFDM) and Polar coded UFMC (PC-UFMC) in massive MIMO scenario. Simulation results indicate that the proposed PC-F-OFDM systems significantly outperform the PC-UFMC systems in AWGN channel. But in massive MIMO setup BER performance of PC-UFMC is better than PC-F-OFDM system.
