The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
The prime focus of this work is in describing a symbiotic architecture for a Cognitive Radio network, called Cognitive Relaying with Frequency Incentive. The incumbent Primary User (PU) of the spectrum, with a weak transmission link, seeks cooperation from the cognitive Secondary User (SU) nodes in its vicinity, and in return rewards them with incentive frequency bands for their own communication...
In this paper, we propose a novel asymmetric resource allocation (RA) scheme for the decode-and-forward (DF) multi-relay based Long Term Evolution Advanced (LTE-Advanced) system, with the orthogonal frequency division multiplexing (OFDM) modulation. Given a fixed total transmit time duration, the time slot durations for the two hops via each of the K relays are designed to be asymmetric, which increases...
In this paper, we propose a dynamic power allocation scheme for a single-relay network based on orthogonal frequency division multiplexing (OFDM) modulation with limited feedback.We consider an Amplify-and-Forward (AF) cooperative diversity model, where one source node communicates with one destination node assisted by one half duplex relay. The power allocation scheme employs a codebook of quantized...
In this paper, joint optimization of subcarrier pairing, relay selection and power allocation is formulated through a capacity maximization problem in orthogonal frequency division multiplexing (OFDM) relay systems, with fairness considerations and individual power constraint on each node. Because achieving the optimal solution is computationally demanding, which is resulted from the excessive possibilities...
This paper considers a multi-source orthogonal frequency division multiplexing (OFDM)-based network of access points wherein dedicated relays use the decode-and-forward relaying. We investigate the joint problem of transmission strategy selection (relaying v/s direct), relay assignment, and power allocation to maximize the minimum rate across sources in two different cooperative scenarios: subcarrier-based...
We consider a multi-source mesh network of static access points wherein sources use decode-and-forward to cooperate with each other. All transmissions use orthogonal frequency division multiplexing (OFDM). Our objective is to maximize the minimum achievable rate across all flows. We find a tight upper bound on the performance of the subcarrier-based cooperation and show that selecting a single relay...
In this paper, we will study the joint problem of power allocation, relay selection and subchannel pairing in OFDM based amplify-and-forward multiple relays system. The optimization problem of maximizing system capacity under joint power constraint at source and relays is firstly formulated. Then, based on Lagrangian dual method, an optimal algorithm to the problem is derived with high SNR assumption...
In this paper, we study the resource allocation problem in relay aided two-hop uplink multi-user transmission with a single relay node and a single destination node. The orthogonal frequency division multiple access (OFDMA) is adopted as the main transmission modulation. We investigate the problems of subcarrier allocation, subcarrier coupling, and power allocation. The optimization is formulated...
Capacity and coverage of a Frequency Division Multiple Access (OFDMA) network can be greatly enhanced by dynamically allocate the radio transmission resources. By including the radio resources of cooperative nodes and taking into account the fairness issue, we present a simple suboptimal solution to the problem of radio resource allocation in relaybased OFDMA cellular systems. We restrict our investigation...
This paper proposes a new architecture for cooperative communication in wireless ad-hoc networks particularly suitable to emergency and safety applications. The proposed solution is characterized by the following relevant features: (a) a wireless connection between each couple of network nodes is established via multiple relays; (b) each source-to-destination link is characterized by a double string...
This paper investigates the resource allocation problem in the downlink of OFDMA cooperative relaying networks with one source (base station) and multiple relay and destination nodes. Assuming that the base station knows all the instantaneous channel gains of all links, we propose a dynamic joint subchannel and power allocation (SPA) scheme whose objective is to maximize the worst user's data rate...
Relaying and orthogonal frequency division multiple access (OFDMA) are the accepted technologies for emerging wireless communications standards. The activities in many wireless standardization bodies and forums, for example IEEE 802.16 j/m and LTE-Advanced, attest to this fact. The availability or lack thereof of efficient radio resource management (RRM) could make or mar the opportunities in these...
Cognitive radio has been proposed in recent years to promote the spectrum utilization by exploiting the existence of spectrum holes. The heterogeneity of both spectrum availability and traffic demand in secondary users has brought significant challenge for efficient spectrum allocation in cognitive radio networks. Observing that spectrum resource can be better matched to traffic demand of secondary...
The solutions to an optimal power allocation problem in dual-hop amplify-and-forward (non-regenerative) OFDM relay systems over given channel gains are provided with a joint transmit power constraint. We analytically derive the allocated power to each hop/subcarrier that satisfies the Karush-Kuhn-Tucker (KKT) conditions by solving simultaneous equations. The solutions imply that at most 3N - 1 possible...
This paper focuses on subchannel and power allocation problem in OFDMA-based decode-and-forward (DF) cooperative relay networks. The objective of this problem is to maximize the total data rate under the constraints of joint total transmission power and subchannels occupation, while maintaining the maximum fairness among multiple relay nodes. We transform this mixed integer programming problem to...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.