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Orthogonal Frequency Division Multiplexing (OFDM) is very sensitive to carrier frequency offsets (CFO). The CFO results in intercarrier interference (ICI). This drawback of OFDM is inherited to Orthogonal Frequency Division Multiple Access (OFDMA). In this paper, we propose a new ICI model for an uplink OFDMA system that takes into account the presence of the cyclic prefix which is usually ignored...
Multi-user cognitive orthogonal frequency division multiplexing (MU-COFDM) is a promising technique for achieving high transmission capacity in future cellular and wireless local area network (WLAN) systems. Multi-user resource allocation with the target of maximizing the transmit capacity of cognitive users and satisfying the proportional rate constraint between cognitive users is proposed under...
We propose a resource allocation algorithm for OFDM system to provide QoS guarantee for unicast and multicast service concurrently. The optimization objective is to maximize the sum rate of the unicast service under the constraint of both the total power and the minimal rate provision of the multicast service, which can be solved by traditional two-step approach. To decrease the complexity, a greedy-based...
In this paper new bit and power loading (BPL) algorithm is presented, which is suitable for application in non-orthogonal multicarrier (NOMC) systems. Its main idea bases on the J. Campello's approach, originally designed for orthogonal multicarrier systems, like orthogonal frequency division multiplexing (OFDM). In the proposed solution, the NOMC-specific features are considered, i.e. two-dimensional...
In this paper, we study power allocation (PA) in a single-relay OFDM system with limited feedback. We propose a PA scheme that uses a codebook of quantized PA vectors designed offline and known to the source, relay, and destination. The destination, which has full knowledge of channel side information (CSI), chooses one of the codebook vectors and conveys back to the source and relay. With the limited...
Some communication applications, like multimedia, deliver data of different importance classes allowing unequal error protection (UEP) levels. In this paper, a multiple-input multiple-output (MIMO) system using orthogonal frequency division multiplexing (OFDM) is considered with a new UEP bit-loading algorithm based on the non-UEP algorithm by Chow, Cioffi, and Bingham. In the proposed bit-loading...
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