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.
Cognitive radio (CR) technology provides great flexibility in spectrum utilization with orthogonal frequency-division multiplexing (OFDM) as its candidate transmission technique. In this paper, we propose a simple spectrum shaping scheme for OFDM-based CRs to enhance spectral compactness and ensure bandwidth efficiency. By mapping antipodal symbol pairs onto adjacent subcarriers at the edges of the...
This paper proposes a bit-interleaved coded transmission with multilevel modulation for multiple-input multiple-output orthogonal frequency-division multiplexing (MIMO-OFDM) systems. In the proposed system, multiple layers are encoded and interleaved together, using one encoder and one interleaver, and then mapped by hierarchical symbol mapping. A corresponding receiver structure is presented, where...
This paper proposes a novel orthogonal frequency- division multiplexing (OFDM)-based iterative channel estimation and irregular repeat-accumulate (IRA) decoding scheme where the pilot symbols are encoded along with the input data and are used for both channel estimation and decoding. To achieve the objective of minimizing the bit error rate, this paper employs systematic IRA codes so that pilot symbols...
In OFDMA cellular system, the inter-cell interference is main interference of the system, which greatly degrades the system performance. In the inter-cell interference mitigation scheme, interference cancellation based on IDMA is a potential technology, especially in full-loaded scenario. Although it can enhance the system performance, its well work needs many information such as MCS, which makes...
MIMO-OFDM receivers with horizontal encoding are considered in this paper. The successive interference cancellation (SIC) algorithm is compared to the K-best list sphere detector (LSD). A modification to the K-best LSD algorithm is introduced. The SIC and K-best LSD receivers are designed for a 2 times 2 antenna system with 64-quadrature amplitude modulation (QAM). The ASIC implementation results...
In this paper, we present a floating-point model for OFDM part of the IEEE 802.16a standard. This part has been assigned as the mandatory structure for WiMax. Next, we present a bit-true model for Viterbi decoder and encoder of it with the constraint of having less than 0.5 dB degradation in the performance of the system while minimizing the hardware cost of it. Since the most sensitive modulation...
To improve performance of orthogonal frequency division multiplexing (OFDM) for fading channels, this paper proposes increasing frequency and time diversity using linear dispersion codes (LDC-OFDM). Methods of LDC-OFDM processing are proposed for both zero-padding (ZP) and cyclic-prefix (CP) type guard intervals. A two-step-estimation (TSE) decoding strategy is proposed that decouples symbol estimation...
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.