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The Fano sequential decoding algorithm can provide lower hardware complexity when compared with the Viterbi algorithm, but it has variable computational delay similar to the other sequential decoding algorithms and the delay is significantly high at low SNR values. Bidirectional decoding technique can be applied to reduce the delay, but hardware resources consumed must be considered. In this paper,...
In this paper, we study different schemes to parallelize trellis algorithms for efficient implementation on a GPU. We consider parallelization schemes at the packet-level, subblock-level and trellis-level to increase the number of threads in a GPU implementation. At the trellis-level, we consider state-level, forward-backward traversal and branch-metric parallelism. To evaluate the performance of...
In this paper1, we propose a novel cooperative scheme to enhance the performance of multiple-access (MA) differential-chaos-shift-keying (DCSK) systems. We provide the bit-error-rate (BER) performance and throughput analyses for the new system with a decode-and-forward (DF) protocol over Nakagami-m fading channels. Our simulated results not only show that this system significantly improves the BER...
Next generation wireless networks are expected to be Heterogeneous consisting of several wireless technologies such as 3G, WLAN, WiMAX, LTE etc. Users of future mobile networks will be able to choose from different radio access technologies. These networks vary widely in service capabilities such as coverage area, bandwidth and error characteristics. Network selection is a challenging task in heterogeneous...
WiMAX is based on the standard IEEE 802.16e-2009 for wireless access in Metropolitan Area Networks. It is one of the solutions for 4G IP based wireless technology. WiMAX utilizes Orthogonal Frequency Division Multiple Access which also supports Multicast and Broadcast Service with appropriate Modulation and Coding Scheme. Presently, Scheduling and Resource allocation algorithm in Opportunistic Layered...
Spectrum opportunities in time, space and power domain are exploited by secondary users in traditional cognitive radio studies. While spectrum opportunities in polarization domain, namely simultaneous utilization of spectrum between primary and secondary system with polarization signal characteristics, is exploited inadequately. With the merits of polarization mismatch, primary system lies in the...
In wireless networks, physical-layer network coding (PNC) is a practical technique to utilize the addition of two simultaneous arriving electromagnetic (EM) waves and realize exchanging messages in two time slots. When several nodes (more than two) need to exchange messages through one relay node, traditional PNC scheme can't deal with the addition of more than two EM waves. The paper proposes an...
This paper presents a turbo-decoder ASIC for 3GPP LTE-Advanced supporting all specified code rates and block sizes. The highly parallelized architecture employs 16 SISO decoders with an optimized state-metric initialization scheme that reduces SISO-decoder latency, which is key for achieving very-high throughput. A novel CRC implementation for parallel turbo decoding prevents the decoder from performing...
This study investigates a variety of high-throughput decoder architectures designed for high-rate low-density parity-check (LDPC) codes. To implement a high-throughput decoder, a fully-parallel architecture can be adopted, but with complex interconnections. In order to reduce the routing complexity, a Split-Row Threshold decoder can be adopted. However, the high check-node degree of a high-rate LDPC...
We present the design of a cross-layer protocol to maintain connectivity in an earthquake monitoring and early warning sensor network in the absence of communications infrastructure. Such systems, by design, warn of events that severely damage or destroy communications infrastructure. However, the data they provide is of critical importance to emergency and rescue decision making in the immediate...
Turbo decoders for modern wireless communication systems are required to support a wide range of code rates. The maximum supported code rate has strong impact on the choice of turbo decoder algorithm and architecture. This paper explores the problem of achieving high performance with turbo decoders at high code rates, and provides solutions on algorithmic and architectural level. A standard-compliant...
Multiple-input multiple-output (MIMO) technique can significantly increase data throughput without sacrificing additional bandwidth. This paper proposes a soft-output K-Best detector for 4×4 64-QAM MIMO system to achieve Gbps throughput. The key contribution of this work is proposing the relaxed 2-parallelism sorting scheme which can produce two survivor paths simultaneously, thus significantly improve...
In this paper, a trade-off analysis between concatenated codes consisting of a convolutional (CC) followed by a Reed-Solomon (RS) code versus low-density parity-check (LDPC) codes is presented. The analysis is based on a twofold criterion: coding gain for a target bit error rate (BER) of 10−6 and required decoder hardware complexity for a target data throughput of 10 Gbps. Furthermore, we have investigated...
This paper describes the exploitation of physical layer confidence in bits (SoftPHY) in order to improve the rate selection in a bit-interleaved coded orthogonal frequency division multiplexing (BIC-OFDM) system. Instead of relying on a measured instantaneous bit error rate (I-BER) from received packets, we built a closed-form I-BER expression that gives accurate and simple functional mapping between...
In this paper, we propose a novel cooperative transmission strategy with broadcasting and cellular communication in a hybrid network system. With the help of cellular base station (CBS), two cooperative schemes are analyzed to improve broadcast performance. We define two thresholds in this paper. For users whose channel quality information (CQI) is less than the low threshold, e.g., the users near...
This paper discusses the IVC (Inter Vehicle Communication) system for ITS. DS-SS (Direct Sequence Spread Spectrum) is used for the IVC because it has CDMA (Code Division Multiple Access) capability. However, efficient PN code allocation scheme is a problem to solve because the vehicles communication directly without base stations. In this paper, the location oriented PN code allocation scheme is adopted...
This paper addresses the issue of packet scheduling with spatial division multiplexing (SDM) techniques of multiple input multiple output (MIMO) antenna in the 3GPP Long Term Evolution (LTE) downlink. Considering the restricted condition of selecting SDM techniques, a novel packet scheduling algorithm with quality of service (QoS) support in LTE downlink MIMO system, named QoS-DMO, is proposed. QoS-DMO...
This paper studies the throughput performance of wireless ad hoc networks when nodes are equipped with the Vertical Bell Labs Layered Space-Time (V-BLAST) system. To accomplish this task, we present an implementation of V-BLAST in the ns-3 network simulator that is based on the original work of Loyka and Gagnon, who have developed analytical expressions for the average bit error rate of V-BLAST. Such...
Interference resources such as noise, adjacent channel interference, co-channel interference and free space loss can decrease the signal to noise ratio (SNR) in a radio network. Different types of antennas such as directional antennas can improve the SNR in a radio network by increasing the signal strength per bit. In this paper, we design a radio network with mobile jammer node and two stationary...
Limited feedback of channel state information (CSI), which is made up of rank indicator (RI), precoding matrix indicator (PMI) and channel quality indicator (CQI), is an important part in closed-loop transmission for 3GPP Long Time Evolution (LTE)/LTE-Advanced standard. In this paper, an efficient way, where PMI granularity selection method is used in PMI feedback mechanism, is presented to adaptively...
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