Serwis Infona wykorzystuje pliki cookies (ciasteczka). Są to wartości tekstowe, zapamiętywane przez przeglądarkę na urządzeniu użytkownika. Nasz serwis ma dostęp do tych wartości oraz wykorzystuje je do zapamiętania danych dotyczących użytkownika, takich jak np. ustawienia (typu widok ekranu, wybór języka interfejsu), zapamiętanie zalogowania. Korzystanie z serwisu Infona oznacza zgodę na zapis informacji i ich wykorzystanie dla celów korzytania z serwisu. Więcej informacji można znaleźć w Polityce prywatności oraz Regulaminie serwisu. Zamknięcie tego okienka potwierdza zapoznanie się z informacją o plikach cookies, akceptację polityki prywatności i regulaminu oraz sposobu wykorzystywania plików cookies w serwisie. Możesz zmienić ustawienia obsługi cookies w swojej przeglądarce.
This paper presents our research in developing high performance but low complexity MIMO decoders for the newest WLAN, i.e. 802.11ac. K-best and Trellis methods are proposed to develop the MIMO decoders. Their performances are observed and compared to MIMO decoders which are based on linear and optimal methods, i.e. ZF, MMSE, and ML. Run test of 2×2 MEMO, 64-QAM, Coding rate 3/4, and 40MHz of bandwidth...
This paper considers an orthogonal frequency division multiplexing (OFDM) based two-way cognitive radio (CR) multiuser multiple relay network. The target is to jointly solve the problem of power allocation, subcarrier assignment, selection of best relay/s, and the sub-carrier pairing at the relay nodes. The aim of the optimization is to maximize the end-to-end sum rate of the network under exclusive...
In this study, a Long Term Evolution Advanced (LTEa) — based multi-user Orthogonal Frequency Division Multiple Access (OFDMA) heterogeneous network has been simulated and a resource allocation strategy has been proposed. The strategy under consideration can inherently mitigate electromagnetic interference, hence increases the mean number of terminals, and requires no channel state information (CSI)...
Exponential growing of wireless multimedia communications has forced the IEEE802.11 workgroup to define new standard of WLAN. It is named a Very High Throughput WLAN IEEE 802.11ac which exploits MIMO-OFDM technology to provide up to 6,9Gbps of throughput. MIMO decoder is the vital part of WLAN 802.11ac. It decodes the received signals to get back the transmitted information. There are many methods...
This paper presents a new eight-parallel multi-path delay commutator (MDC) FFT processor based on the novel modified radix-26 FFT algorithm. The proposed FFT processor can achieve a high throughput and a low hardware complexity by using the efficient scheduling scheme that reorders data-paths. The proposed scheduling scheme and CSD approach can reduce the number of complex multipliers.
This paper presents a shared canonical signed digit (CSD) complex constant multiplier for high-speed low-complexity parallel fast Fourier transform (FFT) processors. To reduce the number of twiddle factor (TF) multiplications, the mixed radix −24/23 FFT algorithm is adopted for FFT processor. The 512-point FFT processor using the proposed shared CSD complex constant multiplier has been designed and...
This paper aims to analyze the choice of the guard interval (GI) length in PLC systems to optimize the achievable throughput under power and symbol error-rate (SER) constraints. In general, the GI length is chosen so that there is no interference, i.e. the GI length is greater than or equal to the channel impulse response length. However, many previous works have shown that in PLC systems, this GI...
This work considers to advance the use of radio resources in a wireless network, for two ways communications based on multiple relays by using a maximum weighted bipartite technique in OFDM depended network. The main idea is to make best use of the system by advancing the total throughput of the system. By pairing the best relay and sub carrier between the several pairs of users and improve the throughput...
This paper presents a multi-path delay commutator (MDC) FFT processor for high-speed. The proposed FFT processor can achieve a high throughput by using a parallel datapath scheme and a multi-path delay commutator structure. The proposed processor can provide a low hardware complexity and an efficient scheduling scheme of complex multiplications. The proposed efficient scheduling scheme can reduce...
In this paper, we investigate a joint subcarrier- relay assignment and power allocation scheme for amplify-and- forward (AF) based two-way multi-relay networks. We formulate a sumrate maximization optimization problem with individual power constraints on each node. The target is to seek a unified optimalscheme for subcarrier-relay assignment and power allocation. The problem turns out a mixed integer...
This paper investigates coordinated resource allocation for cell-center and cell-edge users in multicell orthogonal frequency division multiple-access (OFDMA) wireless networks. Here, we assume the data symbols of each user is only known by one base station (BS). Referring to the fractional frequency reuse (FFR) scheme, the resources for cell-center and cell-edge users are partitioned. Based on such...
Long Term Evolution (LTE) is considered the most promising cellular system able to support the growing demand of multicast services (e.g., IPTV, video streaming) over mobile terminals. The design of effective strategies for the management of these applications is still an open issue, especially in scenarios where several multicast streams are simultaneously transmitted in a cell. In this paper we...
In this paper, we propose an optimal resource allocation algorithm that maximizes the energy efficiency (EE) of a downlink (DL) multi-user orthogonal frequency division multiplexing (OFDM) system subject to a constraint on the total transmit power of the base station (BS). We show that the optimal EE is obtained by first allocating each subcarrier to the user equipment (UE) with the best channel power...
In this paper, we investigate the energy consumption issue of Cognitive Radio (CR) systems. We aim to maximize the energy efficiency of the considered CR system with practical constraints, such as the power budget of the CR system, the interference thresholds of the primary users, the minimal throughput requirements and the proportional fairness of the CR users. Since the formulated mixed integer...
In Cognitive Radio Networks (CRNs) secondary users (SUs) are allowed to transmit data exploiting the wireless resources (i.e., channels) not utilized by licensed primary users (PUs). Efficient resource discovery for finding available channels is a key aspect for successful SUs' operation. In this paper we investigate and propose different algorithms to discover the best CRN channels that, exploited...
In this paper, we study the coexistence issues of LTE systems operating in the TV white spaces. The study includes a proposal for an appropriate system design as well as a discussion on the LTE system's self-configurability to avoid potential interference to other systems when the resource allocation is made flexible. This is evaluated in terms of achievable PHY-layer throughput and block error rates...
In typical resource allocation for Orthogonal Frequency Division Multiple Access (OFDMA), assigning subcarriers to the more favorable users provides beneficial diversity and increased system performance. It is however relevant to consider OFDMA resource allocation with a subcarrier adjacency restriction, grouping a number of adjacent subcarriers into a chunk, both for physical design simplicity and...
In this paper, we present a novel modified radix-25 algorithm for 512-point fast Fourier transform (FFT) computation and high-speed eight-parallel data-path architecture for multi-gigabit wireless personal area network (WPAN) systems. The proposed FFT processor can provide a high data throughput and low hardware complexity by using eight-parallel data-path and multi-path delay-feedback (MDF) structure...
This paper describes a method to mitigate interference when the cyclic prefix (CP) is totally removed for shaped orthogonal frequency division multiplexing (OFDM) signals. The CP is removed to increase system throughput while shaping is applied to increase the spectral efficiency. Samples in the shaping extension are used to restore part of the cyclicity information missing in the ith received symbol...
In cognitive radio settings with highly dynamic primary activities and with small opportunities for secondary access, the requirement to fairly distribute the temporarily available spectral ranges among the unlicensed users turns out to be of particular relevance. The current paper addresses this issue by presenting a new design formulation that aims to optimize the performance of an orthogonal-frequency-division-multiple-access...
Podaj zakres dat dla filtrowania wyświetlonych wyników. Możesz podać datę początkową, końcową lub obie daty. Daty możesz wpisać ręcznie lub wybrać za pomocą kalendarza.