Serwis Infona wykorzystuje pliki cookies (ciasteczka). Są to wartości tekstowe, zapamiętywane przez przeglądarkę na urządzeniu użytkownika. Nasz serwis ma dostęp do tych wartości oraz wykorzystuje je do zapamiętania danych dotyczących użytkownika, takich jak np. ustawienia (typu widok ekranu, wybór języka interfejsu), zapamiętanie zalogowania. Korzystanie z serwisu Infona oznacza zgodę na zapis informacji i ich wykorzystanie dla celów korzytania z serwisu. Więcej informacji można znaleźć w Polityce prywatności oraz Regulaminie serwisu. Zamknięcie tego okienka potwierdza zapoznanie się z informacją o plikach cookies, akceptację polityki prywatności i regulaminu oraz sposobu wykorzystywania plików cookies w serwisie. Możesz zmienić ustawienia obsługi cookies w swojej przeglądarce.
In recent decades, due to limitation of radio spectrum and increasing users in wireless networks, spectral efficiency has been a considerable issue in literatures. In addition, energy consumption is rapidly increasing in wireless communications due to growing demand for wireless technologies especially cellular networks. Therefore, energy efficiency has become an important issue in such networks....
In cooperative wireless communications, beamforming at relays can be employed to increase the signal-to-noise ratio (SNR). Since beamforming at relays requires that channel state information (CSI) be exchanged, an efficient CSI feedback scheme is proposed to reduce the feedback overhead incorporating an optimization of the combining and beamforming weights. With 802.16e OFDMA time-division duplexing...
Zero-Padding Orthogonal Frequency Division Multiplexing (ZP-OFDM) has recently been introduced to avoid coded-OFDM's high decoding complexity. Various sub-optimal ZP-OFDM receivers have been developed in the literature to tradeoff performance with implementation complexity. In this paper, we propose a new iterative detection scheme for ZP-OFDM transmissions tailored to broadband cooperative networks...
Cooperative diversity methods are used to increase network throughput while considering fairness. By using these methods in OFDMA relay-enhanced systems, the best transmission link between direct transmission link and decode-and-forward relaying link is selected dynamically. In this paper, we improved the resource allocation algorithms introduced by Wang et. al. by proposing two new decision criteria...
We consider a wireless relay network where two pairs of nodes exchange information with their partners through a single amplify-and-forward two-way relay with each node equipped with multiple antennas. We propose a new relaying scheme employing OFDMA for the multiple access transmission in the first time slot and OFDM/SDMA for the broadcast transmission in the second time slot to improve the sum rate...
IEEE 802.16j is to enable the operation of multi-hop Relay Stations (RS). It aims to enhance the coverage, per user throughput and system capacity of IEEE 802.16e. However, the Mobile Stations (MSs) which connect to the RS are suffering from exponentially throughput degradation and end-to-end delay increase in congested network. As the number of RS hops increases, so does the degradation and the delay...
Orthogonal frequency division multiple access (OFDMA)-based multi-hop cellular networks, benefited from the relay and OFDM technologies, have a lot of advantages over traditional wireless cellular networks including better network coverage via relay station (RS), the flexibility and adaptation in radio resource allocation. In this paper, the radio resource allocation for wireless relay links in OFDMA-based...
For the orthogonal frequency division multiple access (OFDMA) networks that adopt relaying technology, this paper suggests a novel two hop scheduling scheme that adjusts the transmission time of each hop. Since relays cannot forward data until they receive data from base station, the data transmission consists of two hops for base station to relay and relay to mobile station. In this case, wireless...
We consider a relay-assisted wireless communication system where relays are given the capability of scheduling function. We evaluate and compare the performances of voice over internet protocol (VoIP) in orthogonal frequency division multiple access (OFDMA) systems where two different scheduling capabilities of relays are employed in each system. In the system with relays that have the scheduling...
In this paper, an effective joint allocation of power and subcarriers is proposed under the total power constraint, aiming to maximize the capacity of OFDMA relaying network. In DF (decode and forward) scheme, an equivalent transmit rate formulation is developed, optimal power allocation is obtained by linear optimization and Lagrange multiplier method. By using this optimal power allocation, an efficient...
For supporting the high quality of service (QoS) in relay network, this paper proposes a new scheduling scheme that can be adopted in the orthogonal frequency division multiple access (OFDMA) cellular systems. In relay-aided network, a relay station should receive data from base station for forwarding data to its serving mobile stations. In addition, since the channel quality of each hop cannot be...
An adaptive resource allocation scheme is proposed for regenerative relay-based orthogonal frequency division multiplexing access systems. This scheme allocates subchannels to guarantee fairness between users, and also saves energy by minimising the transmission power. The subchannel allocation for data rate fairness is considered between direct link users and relay stations in the first time subslot...
This work centers on the downlink scheduling algorithm for such cellular wireless networks with relays as IEEE802.16j. We propose an efficient algorithm to discover concurrent transmission scenarios under a multihop relay environment, while applying the back-pressure flow control mechanism to reflect the dynamic queue status of each relay station. Then, we develop a linear programming algorithm for...
The wireless relay mesh network (WRMN) is designed to provide robust and fault tolerant communications between relay and user nodes in broadband wireless networks. In this paper, we study interference aware resource allocation in OFDMA based WRMNs and the effects of spatial reuse on throughput. We propose an interference aware subcarrier assignment (IASA) algorithm to allocate subcarriers to links...
This paper considers subcarrier allocation for the multihop orthogonal frequency division multiple-access (OFDMA) broadcast networks consisting of one source, multiple destinations, and one amplify-and-forward (AF) relay. In this paper, proportional fair (PF) based subcarrier allocation is discussed to get a tradeoff between the system transmission rate and fairness. First, the problem is formulated...
We address the coverage range extension of wireless mesh networks (WMNs) by motivating traffic relaying by in-range network subscribers. Two different game models for non-cooperative users are discussed: a primary market model in which all in-range and out-of-range customers subscribe to one provider, and a primary-secondary market model in which some in-range customers are secondary providers and...
In this paper we analyze the end-to-end capacity of subcarrier pairing strageties of OFDMA-base DF relay link over Rayleigh fading channels. We compare fixed pairing strategy to optimal pairing strategy in the circumstance that the relay is fixed or mobile.The main contribution of this paper is deriving the closed-form expressions for average end-to-end SNR and capacity in these circumstances. The...
This paper studies the optimal resource allocation problem for the relay-assisted orthogonal frequency-division multiple-access (OFDMA) -based multiuser system. A new transmission protocol, named hierarchical OFDMA, is proposed to support two-way transmissions between the base station (BS) and each mobile user (MU) with or without an assisting relay station (RS) in "relay" or "direct"...
We propose an adaptive relay selection scheme for a regenerative orthogonal frequency division multiplexing access (OFDMA) relay network with fairness constraints. The proposed scheme selects the best M relays out of a set of K potential relays to maximize the system capacity. Among these selected relays, subcarriers are reallocated to satisfy fairness constraints as well as to minimize the decrease...
This paper proposes a novel approach to interference avoidance via inter-cell relaying in cellular OFDMA-TDD (orthogonal frequency division multiple access - time division duplex) systems. The proposed scheme, termed asymmetry balancing, is targeted towards next-generation cellular wireless systems which are envisaged to have ad hoc and multi-hop capabilities. Asymmetry balancing resolves the detrimental...
Podaj zakres dat dla filtrowania wyświetlonych wyników. Możesz podać datę początkową, końcową lub obie daty. Daty możesz wpisać ręcznie lub wybrać za pomocą kalendarza.