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.
In this paper, we consider the group oriented beamforming taking into account the quality of service (QoS) requirement for multimedia applications in multiuser/multi-rate OFDM system. The aim of this paper is to find the scheme for maximizing the system throughput while guarantee the QoS requirements and fairness for all services. The simulation result indicates that this scheme proposed in this paper...
Fourth Generation Networks will invariably adopt MIMO-OFDMA techniques, in order to cope with increased data rate demands and improved Quality of Service (QoS) requirements. OFDMA is a popular multiple access candidate, since it facilitates multi-user diversity by enabling two dimensional multiple access, in time and frequency domains. Random Beamforming enables exploitation of spatial multi-user...
The opportunistic beamforming (OB) technique in multicellular OFDMA networks is investigated in this paper. For this reason, three cross-layer radio resource management (RRM) algorithms for OFDMA operational scenarios that are based on typical resource allocation targets such as minimization of transmit power, maximization of throughput and interference averaging are considered. The OB concept is...
To enable ubiquitous end-to-end quality of service over IP networks expanding to rural areas, we examine resource allocation problems of a MAC layer for an OFDM MIMO wireless base station (BS) using multiuser beamforming. We compare two linear beamforming techniques, zero-forcing (ZF-BF) and minimum mean square error (MMSE-BF). To guarantee minimum bandwidth and low packet delay in an environment...
In this paper, a new user scheduling strategy is proposed for multiuser MIMO-OFDM system with a low complexity generalized beamforming (GBF) scheme. In GBF, user antenna outputs are linearly combined with the receive GBF vector to construct an equivalent MISO downlink channel for each subcarrier. The scheduler located at the base station allocates data streams to users based on the subchannel gains...
The resource allocation and limited feedback scheme are proposed in multiuser MIMO OFDM systems. The optimization model is to maximize the throughput with minimal and maximal transmit rate constraint of users, which can effectively guarantees the QoS requirement of multimedia traffics. The resource allocation is divided into user selection and power allocation, realizing the optimization separately...
For the downlink of MIMO-OFDM system, a novel proportional fairness with joint space-time-frequency scheduling is proposed in this paper. On one hand, by space-time-frequency scheduling one can gain multiuser spatial multiplexing on the same subcarrier in one timeslot. On the other hand, with modified traditional proportional fairness, the system can provide QoS guarantee for various service types...
This paper presents a cross-layer concept with respect to a joint design of beamforming and scheduling in a cellular MIMO-OFDM-based network. Conventionally, the beamforming and scheduling processes are designed more or less independently of each other. In contrast, this paper describes a combined approach of the scheduling and beamforming procedure, with the aim to maximize the capacity and fulfill...
In this paper, we have formulated the problem of cross layer throughput-maximized dynamic resource management with guaranteed QoS in MIMO OFDM beamforming systems. In order to reduce of the amount of feedback information and computation complexity, OFDM subcarriers are grouped into subchannels based on the fact that adjacent subcarriers experience the same fading. According to characteristics of various...
In a cellular system with partial channel state information, i.e. with limited feedback, and multiple antennas, we consider scheduling of downlink transmissions at the base station using beamforming and orthogonal frequency division multiplexing. As the complexity of optimal scheduling for throughput maximization under quality of service constraints grows exponentially with the number of subcarriers,...
This paper studies the downlink multiuser multiple input multiple output-orthogonal frequency division multiple access (MIMO-OFDMA) system for margin adaptive multiuser eigenmode transmission (MET) with perfect channel state information at the transmitter. In margin adaptive objective, base station (BS) has to satisfy individual quality of service (QoS) constraints of the users subject to transmit...
In order to increase the bandwidth efficiency and further improve the performance of orthogonal frequency division multiplex (OFDM) systems, adaptive resource allocation and smart antennas techniques are widely applied. However, the employment of fully adaptive beamforming in physical layer for OFDM systems significantly raises the issues in medium access control (MAC) layer, hence affects the implementation...
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.