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The backpressure algorithm for dynamic network resource allocation achieves throughput optimality by making use of one-hop queue length differences. This elegant algorithm, on the other hand, does not yield good delay performance in general. We introduce a new class of enhanced dynamic backpressure algorithms which make use of a general queue-dependent bias function to exploit queue state information...
Check node update processing for non-binary LDPC (NB-LDPC) architectures requires a large number of clock cycles, which limits the achievable throughput to tens of Mbps for high rate codes. In this work, we propose a new NB-LDPC architecture based on the Trellis-EMS (T-EMS) algorithm that reduces the number of clock cycles by a factor of dc, by adding an extra column to the trellis. This feature makes...
A prior layer-2 routing algorithm-D2ENDIST demonstrates advantages in throughput improvement, reroute period and failure recovery. Moreover, with the invention of software-defined networking (SDN), a revolutionary networking concept, dynamic routing protocols can embrace more flexible policy on per-flow basis. However, due to runtime complexity of dynamic routing, many issues on the practicality emerge...
Long Term Evolution (LTE) is considered the most promising cellular system able to support the growing demand of multicast services (e.g., IPTV, video streaming) over mobile terminals. The design of effective strategies for the management of these applications is still an open issue, especially in scenarios where several multicast streams are simultaneously transmitted in a cell. In this paper we...
In this paper, we propose an optimal resource allocation algorithm that maximizes the energy efficiency (EE) of a downlink (DL) multi-user orthogonal frequency division multiplexing (OFDM) system subject to a constraint on the total transmit power of the base station (BS). We show that the optimal EE is obtained by first allocating each subcarrier to the user equipment (UE) with the best channel power...
Coordinated multipoint (CoMP) is an interference mitigation technique in LTE release 10, which exploits base station (BS) cooperation to improve throughput for cell-edge users. An important new feature present in CoMP is that variable numbers of BSs can service a given user. This poses a new problem for beamforming that is not present in single-cell operation: the quantization codebook must support...
In recent years, much research has been devoted to the construction of public-private key pairs; on the other hand, few have synthesized the visualization of the producer-consumer problem. Given the current status of efficient archetypes, leading analysts famously desires the emulation of congestion control, which embodies the key principles of hardware and architecture. In our research, we concentrate...
Resource management in heterogeneous wireless networks has been approached from various angles by the research community. The complexity of the network and the heterogeneity of clients make the conclusive comparison of the various resource allocations challenging. This work introduces superBS, an approach defining a theoretical optimal resource allocation that adheres to the required resource management...
Cognitive Radio Network (CRN) technology allows secondary users (SUs) to transmit data exploiting the wireless resources not utilized by licensed primary users (PUs). Channel exploration by SUs for finding transmission opportunities incurs non-negligible costs and is a key challenge in successful operation of CRN. In this paper, we investigate the joint effect of channel exploration order and stopping...
Cognitive Radio Networks (CRNs) aim to maximize the utilization of existing wireless channels by allowing secondary users (SUs) to transmit when licensed primary users (PUs) are not using the same channels. An SU monitors the CRN channels, sensing PU presence to avoid interference and estimating the link quality before transmitting. It stops when one or more available channels with satisfactory link...
In this paper, a new energy efficient resource allocation is designed to maximize the system throughput per unit-energy over frequency selective channels in OFDMA downlink transmissions. Based on a fixed optimization model, the base station allocates transmit power to subcarriers using Water-Filling method and each user has its own water level. The optimal solution of power allocation with a given...
In this work a sphere decoder with low complexity is proposed and implemented. We propose a simplified norm algorithm, which is called admissible set elimination (ASE), to dramatically decrease the number of searching nodes. In addition, the decoder uses table-look-up to acquire the enumeration order of different constellations. As a result, the critical path is shortened and the throughput is enhanced...
This paper presents a high-throughput, hardware-efficient iterative soft-input soft-output signal detector for spatial-multiplexing system. The detector provides near-optimal performance with much reduced complexity by adopting imbalanced tree-travel strategy, LLR correction techniques, and iteration-adaptive node-selection method. A multi-stage highly-parallel VLSI architecture is employed to implement...
The high processing complexity of data detection in the large-scale multiple-input multiple-output (MIMO) uplink necessitates high-throughput VLSI implementations. In this paper, we propose — to the best of our knowledge — first matrix inversion implementation suitable for data detection in systems having hundreds of antennas at the base station (BS). The underlying idea is to carry out an approximate...
The problem of finding the shortest route between a source and a destination in a large-scale network is investigated. A simple and efficient technique to reduce the network search space size based on nodes position information is developed. Following the proposed technique, it is shown that the route found within the reduced search space has the same number of hops as that obtained when solving the...
A new method for detecting Spectrally Efficient Frequency Division Multiplexing (SEFDM) is proposed and verified through modelling and practical FPGA implementation. The method is derived through studies of two sphere decoding techniques, namely Fixed SD (FSD) with Sort-Free (SF) and Non-Sort-Free (NSF) algorithms. We report a co-simulation verification framework to verify the performance of these...
In this paper, we investigate the energy consumption issue of Cognitive Radio (CR) systems. We aim to maximize the energy efficiency of the considered CR system with practical constraints, such as the power budget of the CR system, the interference thresholds of the primary users, the minimal throughput requirements and the proportional fairness of the CR users. Since the formulated mixed integer...
Interference management is an important problem in wireless networks. In this paper, we focus on the successive interference cancellation (SIC) technique, and aim to design an efficient cross-layer solution to increase throughput for multi-hop wireless networks with SIC. We realize that the challenge of this problem is its mixed integer linear programming formulation, which has bunches of integer...
Due to the power consumption issue of user equipment (UE), Single-Carrier FDMA (SC-FDMA) has been selected as the uplink multiple access scheme of 3GPP Long Term Evolution (LTE). Similar to OFDMA downlink, SC-FDMA enables multiple UEs to be served simultaneously in uplink as well. However, the single carrier characteristic requires that all the allocated subcarriers to a UE must be contiguous in frequency...
In Cognitive Radio Networks (CRNs) secondary users (SUs) are allowed to transmit data exploiting the wireless resources (i.e., channels) not utilized by licensed primary users (PUs). Efficient resource discovery for finding available channels is a key aspect for successful SUs' operation. In this paper we investigate and propose different algorithms to discover the best CRN channels that, exploited...
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