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.
Adaptive bit-loading algorithms can improve the performance of OFDM systems significantly. The tradeoff between the algorithms performance (optimum solution) and the computational complexity is essential for implementation of loading algorithms. In this paper, we present a low complexity non-iterative discrete bit-loading algorithm to maximize the data rate subject to specified target BER and uniform...
The performance reduction caused by inter-carrier interference (ICI) on orthogonal frequency division multiplexing (OFDM) systems over time-varying channels is relevant especially when large OFDM symbols are employed in order to achieve an higher throughput. In this paper we propose a design method of an equalization scheme using several full-length FFTs operating on non-overlapping windows of the...
In this paper, a new SLM scheme for peak to average power ratio (PAPR) reduction in orthogonal frequency division multiplexing (OFDM) systems is proposed. This scheme is special case of selected mapping (SLM) scheme. The proposed SLM scheme generates alternative OFDM signal sequences by exploiting the intermediate OFDM signal sequence in inverse fast Fourier transform (IFFT). By using this technique,...
This paper proposes a bit loading algorithm for orthogonal frequency division multiplexing (OFDM) systems. With the restrictions of available transmit power and required bit-error-rate (BER) performance, the algorithm aims at achieving the maximal data rate. Although the proposed algorithm is based on the Hughes-hartogs algorithm, the computational complexity is only O(k × M), where k denotes the...
A modified subspace-based blind channel estimation algorithm for OFDM systems is proposed in this paper. A systematic approach is used to construct the signal matrix in the proposed algorithm. Compared with conventional subspace- based blind channel estimation algorithm, the proposed algorithm has lower computational complexity and higher probability of full row rank for the corresponding signal matrix...
A local linear regression (LLR) based least-square (LS) channel estimation technique for mobile orthogonal frequency division multiplexing (OFDM) communication systems over the doubly selective fading channel is proposed in this paper. In our proposed method, the doubly selective fading channel is firstly estimated via pilots arranged in block-type, comb-type or distributed pilot scheme, piece-wise...
In this study, pilot-based iterative channel estimation, which use virtual pilots, is proposed for OFDM systems In order to find final channel estimates, instead of averaging the group estimates, which are found by virtual pilots, it is proposed to combine them by taking into account their reliabilities that are calculated by using probability density function. Then the proposed method is compared...
In this paper, we first introduce a new method for joint estimation of IQ imbalance and channel response in OFDM systems under the assumption of perfect frame synchronization. The proposed method needs only one OFDM block for training and the solution is given in closed form. Then the method is applied to the scenario when the OFDM frame is not synchronized. A reduced complexity algorithm is derived...
This paper presents a new bit and power allocation scheme for OFDM systems with low computational complexity in which the overall transmission power is minimized by constraining the fixed data rate and bit error rate. The algorithm and simulation include two stages. The first stage involves the application of a target BER and SNR of each sub-carrier for a variable-rate bit pre-allocation. The second...
Space division multiple access in conjunction with OFDM main drawback associated with orthogonal frequency division efficiency and system capacity. This combination is approaches have been presented in the literature, such as future WLAN implementations. One drawback of OFDM systems is the high peak to average power ratio, which imposes (LNST), and the exponential companding transform (Exp-CT). However,...
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.