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In order to reduce the system computation complexity and delay, we propose a scheme to decrease the iterative time of the carrier synchronization for low-density parity-check (LDPC) codes. The system will stop iteration if the log-likelihood ratio (LLR) message at the output of decoder satisfies the limitary conditions. Simulation results show that the proposed scheme is efficient and there is little...
Received video quality is dependent on the available link rate and the packet loss rate, which are inter-related in a busy network link. Even low packet loss ratios (PLRs) can significantly reduce the video quality. In this paper, a packet level parity FEC is applied to the video stream in order to reduce the video PLR. A constant gross data rate is assumed, such that adding a FEC leads to a decrease...
This paper studies the effects of heterogeneity in DO networks and proposes measures for reducing or removing them. In particular, two types of imbalance, i.e., f-Imbalance and OH-Imbalance are identified and methods for compensating them, i.e., RL padding and AT overhead (OH) channel boost, are proposed. The effectiveness of the proposed methods is demonstrated through both, developing an analytic...
In this paper, we propose an iterative SIC receiver architecture with pilot- and data-based channel estimation for efficient decoding of non-orthogonal superimposed signals. The non-orthogonal superposition concept on top of OFDMA is a promising technique to improve cell spectral efficiency. In the cellular case, where users with significant path loss are superimposed by an intelligent scheduler,...
In this paper, we investigate the benefit of joint network-channel distributed coding for the multiple-access half-duplex relay channel. In contrast with previous work, the medium access is not orthogonal and the source-to-relay links are not error-free, which render the reality of wireless environments and notably complicate the problem. Indeed, due to the broadcast nature of wireless media, transmitted...
There has been a tremendous growth in the wireless communication networks and their applications around us. Different applications developed over wireless networks can have very different requirements. For some applications, protection from transmission errors might be of primary, whereas for other application the security and privacy of the information in transit might be the primary requirement...
Space-time block coded spatial modulation (STBC-SM), which employs space-time block coding (STBC) for spatial modulation (SM), is proposed as a new multiple-input multiple-output (MIMO) transmission scheme. In the STBC-SM scheme, the transmitted information symbols are expanded not only to the space and time domains but also to the spatial (antenna) domain, therefore both core STBC and antenna indices...
In this paper, we undertake a comparison of LDPC (768,384) and convolutional (171,133) codes for 60-GHz OFDM-based wireless communication systems. The comparison is based on two parameters: Frame Error Rate (FER) for 60-GHz channels and decoding hardware complexity for a required throughput of more than 1 Gbps. Additionally, we provide performance parameters of a fully parallel LDPC decoder chip,...
In this paper, we propose a parallel hybrid merge-select sorting approach for the implementation of K-best list sphere detection (LSD) multi-input multi-output (MIMO) decoder based on a recently developed novel Reconfigurable Instruction Cell Array (RICA). Several popular sorting algorithms adopted in MIMO decoding are analyzed and mapped onto our proposed platform. We discuss the targeted K-best...
In downlink relay systems, the conventional straightforward relaying scheme named decode-and-forward (DF) protocol is used at relay station (RS) to decode the data received from base station (BS) and forward the decoded data to the mobile station (MS) to improve the spatial diversity gain. However, conventional DF mode is spectral inefficient and not capacity optimal since the wireless channels in...
During the last few years, several authors have studied the performance of many different types of channel codes for cooperative communication systems. Some of these codes include Low Density Parity Check (LDPC), Turbo and convolutional codes. Published results show that these codes effectively improve both the data rate and system performance in cooperative schemes such as the decode and forward...
In the paper, a modified Log-MAP algorithm based on a novel approximation of the max* operator derived from the Jensen inequality is proposed. In this approach, the max* operation is performed on n≥2 arguments, thus the recursive calculations are avoided and significant reduction in the number of operations performed per decoding step, as compared with the conventional Log-MAP, is achieved. Simulation...
In this paper, a class of quasi-orthogonal space-time block codes (Q-STBC) is proposed for systems with 2 antennas and 3 time slots, where the orthogonal Alamouti code can not be applied due to the “odd symbol” problem inherited in the 3GPP frame structure. The proposed codes can achieve rate one and full diversity with lower complexity maximum likelihood detection. The design takes into consideration...
In this paper, the generation of 16-QAM and 64-QAM space-time trellis codes (STTCs) for several transmit antennas is considered. The main problem with an exhaustive search is the important time to find the best 22n-QAM STTCs, especially for great values of n and for great numbers of transmit antennas. In order to reduce this search time, an efficient method must be used to generate optimal 22n-QAM...
Cooperative communication offers a way to obtain spatial diversity in a wireless network without increasing hardware demands. The different cooperation protocols proposed in the literature are often studied under the assumption that all channel state information is available at the destination. In a practical scenario, channel estimates need to be derived from the broadcasted signals. In this paper,...
In this paper, a cooperative multicast scheme that uses Randomized Distributed Space Time Codes (R-DSTC), along with packet level Forward Error Correction (FEC), is studied. For the source packets, two-hop transmission is considered, where a packet is transmitted first by the access point (AP), and then forwarded using R-DSTC by the nodes that receive the packet. On the other hand, parity packets...
In this paper, an efficient Multiple-input multiple-output (MIMO) detection scheme with low complexity is proposed. The proposed scheme has a feature of combined a QRD-M, which is the M-algorithm combined with QR decomposition, with a complex lattice reduction (LR)-aided detection scheme. For the first T stages, the QRD-M detection is executed. And then, the complex LR-aided detection is executed...
In GERAN networks, Multiple Users Reusing One Single timeslot (MUROS) promises to enhance the cell capacity through pairing of two or more users onto a single timeslot. So far no work has been done on the basis on which the different users would be paired. The criteria used for the pairing decision to pair two or more users is critical for MUROS as this will eventually decide the actual gains due...
In this paper we present a novel Hybrid Automatic Repeat reQuest (HARQ) scheme for cooperative communication systems, called Coded Partial Retransmission (CPR). The method is based on the retransmission of only a fraction of the original codeword by the cooperating nodes, applying an appropriate power allocation. Numerical results using LDPC codes and Type-I HARQ with Chase Combining show that CPR...
In this paper we consider the uplink of a cellular network partitioned into localized jointly decoded cells. These jointly decoded cells are implemented as fixed size clusters. Such networks have a potential for real world deployments with improved spectral efficiency and user experience. Similar to conventional cellular networks, frequency planning can be considered as an efficient method to control...
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