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.
Mobile devices have increasingly been used to run multimedia applications which are extremely downlink-intensive. The conventional rate adaptive and/or margin adaptive approach for radio resource allocation may result in unnecessary energy consumption on mobile devices, which will not be energy efficient for mobile multimedia applications. In this paper, we develop an energy adaptive approach and...
Video multicast exploits the wireless broadcast nature to transmit a video stream to multiple clients with a minimum bandwidth requirement. Scalable video coding (AMC) and Adaptive Modulation and Coding (AMC) are two key techniques for video multicast in broadband wireless networks. They improve the system utility value by dividing the video steam into different layers and assigning appropriate modulation...
Efficient resource allocation is necessary to provide the users with the quality of service promised in modern cellular networks, such as LTE. Traditional allocation methods make use of the smallest granularity available, the physical resource block (PRB), to assign resources to each user. The selected resources assigned to a user form a transport block (TB). However, the standard constrains the use...
In this paper, we propose an improved utility-based radio resource allocation algorithm in orthogonal frequency division multiple access (OFDMA) wireless networks. The queue state information (QSI), channel state information (CSI), QoS requirements and transmitted packets are synthetically considered in the utility function, thus it can meet the needs of networks with multi-service better. Based on...
Relay stations are introduced into cellular systems to extend the coverage of the cell, improve the throughput and outage probability of the system. However, present resource-allocation algorithms for traditional cellular system are not directly applicable to the system with relay stations. In this paper, we propose an adaptive resource-allocation algorithm for orthogonal frequency-division multiple-access...
Scalable video coding with adaptive modulation and coding is a promising technique to provide real-time multicast services for heterogeneous mobile devices. Nevertheless, as the rapid growth of data communication for emerging applications, energy consumption is an critical challenge of mobile devices. This paper targets the problem of resource allocation for scalable video multicast with adaptive...
Orthogonal frequency division multiplexing (OFDM) has several properties which make it an attractive modulation scheme for high speed wireless transmission links. In this paper, a novel power sharing technique is proposed for different users to improve the system performance. The proposed technique is based on use of variable amplitude of subcarriers (VAS). Power can be increased to the users who...
We address the allocation of subcarriers, bits and power among the base stations (BSs) of downlink multi-cell OFDMA systems using the non-cooperative game theoretic approach. The utility function of a player is defined as the difference between the revenue generated from transmitting the bits and the cost of the power consumed. Unlike the commonly adopted water-filling approach where continuous bit...
Orthogonal frequency division multiplexing (OFDM) has several properties which make it an attractive modulation scheme for high speed wireless transmission links. In this paper, a novel power sharing technique is proposed for different users to improve the system performance. The proposed technique is based on use of variable amplitude of subcarriers (VAS). Power can be increased to the users who...
We investigate in this paper the impact of mobility on the capacity of an OFDMA-based mobile WiMAX network in the presence of two types of flows: streaming and elastic, under a dynamic configuration where users come to the system following a Poisson process and leave it after a finite duration. This duration is independent on the amount of resources for streaming flow, such as voice, and proportional...
This paper addresses the adaptive allocation of subcarrier, bit and power resources in the downlink of multicell OFDMA systems, where base stations allocate radio resources in a decentralized manner. Our algorithm uses discrete bit-loading values which is more applicable to the practical systems. Noncooperative game theoretic approach is adopted and we first only include the transmit power and throughput...
The EU WINNER projects have studied OFDM-based packet data systems beyond 3G that use adaptivity on all time- scales to obtain high flexibility and performance. The adaptive transmission in both downlink and uplink is scheduled and controlled at base stations and relay nodes and requires frequent transmission of control information over the downlink. The use of scheduling, adaptive modulation and...
Fair OFDMA (orthogonal frequency division multiple access) based subcarrier allocation algorithm is proposed. The method includes adaptive modulation and power control per subcarrier, considering actual channel state information between users and base station. To heighten dasiafairnesspsila, preliminary power control (PPC) is executed before efficient allocation of radio resources.
IEEE 802.16e WiMAX is a promising new technology for broadband access networks. Amongst the class of applications that can be supported is real time video services (such as IPTV, broadcast of live events etc.). These applications are bandwidth hungry and have stringent delay constraints. Thus, scalable support for such applications is a challenging problem. To address this challenge, we consider a...
In this paper, we propose a robust STBC transmission scheme to combat the timing synchronization errors over frequency-selective multiple-access channels. First, the equivalent channel model in the presence of timing synchronization errors is derived and we find that the synchronization errors result in an equivalent channel model with larger number of correlated channel taps. Based on this correlated...
This paper investigates effects of pilot assisted channel estimation on dynamic resource allocation in a multiuser orthogonal frequency division multiplexing (OFDM) system. The channel estimation is done in each OFDM symbol through least-squared error (LSE) or minimum mean-squared error (MMSE) algorithm. The performance of each of these algorithms is evaluated through computer simulations. The maximal...
More and more users subscribing to wireless broadband services are seeking to have access to both WLAN and UMTS networks. We study individually optimal user-network association in an integrated WLAN and UMTS hybrid cell. The association problem is formulated within a non-cooperative game framework. In the formulation, mobile arrivals are assumed to follow the Poisson process and each mobile considers...
We characterize the total generalized squared correlation (TGSC) for a given signature sequence set used in uplink synchronous code division multiple access (S-CDMA) when channel state information is known perfectly at both transmitter and receiver. We give a definition of the TGSC based on the eigenvalues of Gram matrix associated to signature sequences set for multipath channels in the presence...
Algorithms for dynamic resource allocation in OFDM based wireless systems, known as Marge Adaptive optimization (MA), aim at reducing the total power consumption of the base station under individual minimum transmit rates for terminals. While it has been shown that using adaptive modulation increases the capacity of the wireless system, most MA algorithms may not be energy efficient when many mobile...
In this paper we derive optimal power allocation scheme that minimizes bit error rate (BER) while satisfying the average power constraint and peak to average power ratio (PAPR) constraint (which translates to minimizing the PAPR). The power allocation is done in space and time for multiple-input single-output (MISO) systems over Rayleigh flat fading channels assuming perfect channel state information...
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.