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.
We propose two encoding strategies for a two user cooperative Orthogonal Frequency Division Multiple Access (OFDMA) system, based on block Markov superposition encoding. We obtain the expressions for the resulting achievable rate regions for both encoding strategies, and evaluate them through simulations. We show that, by allowing for re-partitioning and re-encoding of the cooperative messages across...
This paper gives the system model and the STBC encoding and decoding schemes in MIMO-OFDM system according to STBC coding theories. It focuses on researching and simulating the MIMO-OFDM system's performances, which had added STBC. We had analyzed and simulated BER performance of the system with different number of transceiver antennas. At the same time, BER performance of the system with different...
In this paper, we consider the problem of the Space Frequency Block Codes (SFBC) decoding, according to the Maximum A Posteriori (MAP) criterion when the channel is not perfectly known at the receiver. We propose to use the Expectation Maximization (EM) algorithm to solve this problem. Simulation results show that the performance of our iterative decoder using the EM algorithm is very close to the...
Single-carrier frequency-division multiple-access (SC-FDMA) has been adopted in the uplink of the LTE standard due to its lower peak-to-average-power ratio (PAPR) compared to orthogonal frequency-division multiple access (OFDMA). Recent activities in the LTE-advanced (LTE-A) standardization have focused on effective uplink transmit diversity schemes with low PAPR but without considering the performance...
The performance of a wireless communication system is analyzed considering multi-carrier OFDM with Multiple- Input-Multiple-Output (MIMO) wireless channel and Space-Time Block Coding (STBC). Bit Error Rate (BER) expression for MIMO-OFDM system without and with STBC is presented considering fading and timing jitter with QPSK, DPSK and DQPSK modulation schemes. The performance results are evaluated...
The performance of a space-time block coded orthogonal frequency-division multiplexing (STBC-OFDM) system often relies on the assumption of quasi-static channels. For the time-varying multipath channel, co-channel interference (CCI) and inter-carrier interference (ICI) occur and performance degrades seriously. In this paper, we propose an iterative interference cancellation scheme to reduce both CCI...
In forward link multiuser space-time block coded orthogonal frequency division multiplexing (STBC-OFDM) systems, the signal-to-noise power ratio (SNR) of each user's received signal is different from those of others. Thus, when subcarriers are not properly allocated to users, intensive bit errors occur in a specific user. This causes a burst error in such a user, and the number of correctable bits...
We investigate the case of Block Turbo Codes (BTCs) combined with Orthogonal Frequency Division Multiplexing (OFDM) technique for Unmanned Aerial Vehicles (UAVs) highspeed data link. Considering the UAV channel with time-varying and multipath fast fading characteristics, a 3-path UAV channel model is developed, which can be readily implemented under simulation condition. Two typical communication...
In this paper we evaluate the coded and uncoded performance of a 2-antenna terminal relaying scheme, for downlink OFDM based systems, using efficient space-frequency block coding protocols. We consider that the relay and the base station are equipped with 2 antennas and the user terminal has a single antenna. Two types of relay protocols are accounted for: equalize-and-forward and decode-and-forward...
In this paper, with the purpose to exploit the space and the frequency diversity, we propose an amplify-and-forward (AAF) cooperative system using orthogonal frequency division multiplexing (OFDM) with space-frequency codes (SFC). The signal processing algorithm of this presented system is introduced in detail and we also provide the system optimal power allocation strategy. Simulation results prove...
For orthogonal frequency-division multiplexing (OFDM) systems, the length of cyclic prefix (CP) is selected on the basis of the maximum delay spread of channel. However, the use of a CP reduces both the spectral efficiency and the power efficiency. In this paper, we proposed an iterative receiver for the space frequency block code (SFBC) OFDM system without CP. After tail cancellation, our proposed...
This paper proposes multipath division turbo equalization with block inter-carrier interference cancellation (MD-BIC) for orthogonal frequency division multiplexing (OFDM). When the multipath delay difference exceeds the cyclic prefix (CP) length, the OFDM transmission performance suffers severely due to inter-symbol interference (ISI) and inter-carrier interference (ICI). Cellular systems with amplify-and-forward...
This paper proposes a simple physical (PHY) layer design to introduce cooperation in the downlink of an infrastructure-based multicell multiple-input multiple-output (MIMO) orthogonal frequency-division multiplexing (OFDM) network. To improve the cell coverage, a novel PHY layer design is proposed that allows cooperation among an arbitrary and unknown number of base stations (BSs), by suitably randomizing...
Explicit codes are constructed that achieve the diversity-multiplexing gain tradeoff (DMT) of the cooperative-relay channel under the dynamic decode-and-forward protocol for any network size and for all numbers of transmit and receive antennas at the relays. Along the way, we prove that space-time codes previously constructed in the literature for the block-fading and parallel channels are approximately...
In a fast fading channel, the orthogonality of the two consecutive STBC-OFDM symbols will be destroyed and the received signals can not be perfectly separated. As a result, the bit error rate (BER) performance will be degraded seriously. In this paper, we analyze several CCI cancellation decoders for the STBC-OFDM in a fast fading channel including the Alamouti method, SIC method, ML method, DMLD...
This paper proposes an iterative EQ-GM algorithm for SFBC-OFDM systems based on GM channel estimation algorithm and ZF principle. The scheme deduces a frequency domain ZF equalizer for the 2 ?? 2 SFBC-OFDM system to eliminate the channel coefficient differences of the adjacent subcarriers introduced by the frequency selective channel in order to maintain the orthogonality of the SFBC codes at the...
Recently, the turbo-detected sphere packing (SP) aided space-time block-coding (STBC) STBC-SP scheme was demonstrated to provide useful performance improvements over conventionally-modulated orthogonal design based STBC schemes in the context of single-user multiple-input multiple-output (SU-MIMO) systems. Hence, in this treatise we extend its employment to the multi-user MIMO (MU-MIMO) scenario....
Space-time block coded orthogonal frequency division multiplexing (STBC-OFDM) from coordinate interleaved orthogonal design (CIOD) is considered to be an effective space- time code (STC) to achieve full-rate and full-diversity with a simple maximum-likelihood (SML) decoder. However, the SML decoder cannot prevent the performance degradation completely due to time-varying effects such as co-channel...
It has been shown that relaying systems can offer spatial and multipath diversity in amplify-and-forward (AF) relay-assisted transmission over frequency-selective fading channels when trellis coded modulation (TCM) is applied as an outer code. However, the price for such advantages is the high decoding complexity. To overcome this disadvantage, the technique of subcarrier grouping is applied for orthogonal...
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...
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.