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The Device-to-Device (D2D) communication principle is a key enabler of direct localized communication between mobile nodes and is expected to propel a plethora of novel multimedia services. However, even though it offers a wide set of capabilities mainly due to the proximity and resource reuse gains, interference must be carefully controlled to maximize the achievable rate for coexisting cellular...
Node cooperation approaches improve physical layer security in wireless networks without applying data encryption. Selecting the appropriate nodes to cooperate as relays or friendly jammers, to degrade eavesdropper's link, is a challenging problem which has attracted a lot of attention in recent years. Various approaches, based on conventional exhaustive search, have been suggested for optimal relay-jammer...
This paper considers the resource allocation for an orthogonal-frequency-division-multiplexing (OFDM)-based cognitive decode-and-forward (DF) relay network. Our objective is to maximize the sum rate (over subcarriers) of the cognitive-radio user with the interference introduced to the primary users (PUs) being managed. The optimization is over subcarrier pairing and power allocation, which leads to...
IEEE 802.16j supports WiMAX in extending the service area of Base Stations (BSs) through Relay Stations (RSs) for serving more Subscriber Stations (SSs). Effective allocation of resources is key to maximize the number of served SSs for the downlink broadcast service in IEEE 802.16j WiMAX relay network. Most existing studies concentrate on the single-level relay network where the BS sends data to the...
In this paper, we consider a dual-hop wireless multirelay system with decode-and-forward (DF) cooperative protocol. Assuming the knowledge of channel gain magnitudes, we explore adaptive power allocation based on genetic algorithm with a simple opportunistic relay selection strategy to minimize the system outage probability under an aggregate power constraint. Simulation results show that the presented...
Resource allocation of the multiuser cooperative OFDM communication in the LTE-Advance system is mainly investigated in this paper. The object is to maximize the system's throughput under the condition that total power is a fixed constant. With the anti-fading characteristic of OFDM and the space diversity in the cooperative communication, it is proposed in this paper that using genetic algorithm...
Historically, the distribution network has been planned in order to operate in radial configuration. Protective relays are adopted to detect system abnormalities and to execute appropriate commands to isolate swiftly only the faulty component from the healthy system. Nowadays, the regulation schemes implemented by Regulators require that Distribution Companies reduce number and duration of supply...
Future cellular systems demand higher throughput as an important requirement, along with smaller cell sizes to characterize the performance of network services. This paper purposes a way to optimize the multihop cellular network (MCN) deployment in LTE-A/Mobile WiMAX broadband wireless access systems. A simple way to optimize the MCN is to associate direct and multihop users based on maximum channel...
MIMO-relay technology is accepted as a promising solution to improve cell edge performance for the future 4G wireless system. In this paper, an inter-cell interference mitigation scheme based on MIMO-relay technique is proposed to improve the average capacity for cell edge users. In the paper, a new network structure with shared relay station (SRS) is first studied, and a two-tier channel decomposition...
In this paper, the downlink of a cell is considered in an OFDMA-based relay network. In the cell, a base station (BS) and fixed relay stations (RSs) are deployed. Multiple subscriber stations (SS) are located in the cell. A SS is served either by a direct or a two hop connection. In a direct connection, a link between BS and SS exists. In a two hop connection, a link exists between BS and RS and between...
Cooperative relay transmission is an effective way to combat multi-path fading. With proper coding scheme, the diversity and coding gains can be obtained. A two-hop decode- and-forward relay protocol using distributed linear dispersion code (LDC) is introduced and analyzed in terms of capacity gains over the system with the traditional uniform power allocation. To optimize the capacity of the system...
This paper addresses the problem of joint routing and radio resource management in multihop cellular networks with fixed relays. The objective is to maximize the total network utility. This paper focuses on quality of service (QoS-) sensitive applications that are captured by sigmoidal-like utility functions. The non-concavity of the user utility functions, the complex relation between routing decisions...
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