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This paper considers a two-cell uplink cochannel multiple-input–multiple-output (MIMO) network with users sequentially arriving at the network. We study the problem of sequential base-station (BS) selection for the users, with the selection criterion based on the degrees of freedom (DoFs) available for the new arriving user. We find that different sequential BS selections affect individual and network...
In a cognitive radio system, proper configuration of sensing duration enables maximization of the data throughput. However, no existing straightforward formula is available, which is desirable in the mobile context due to tightness of computation time. A set of closed-form approximate formulae of optimal sensing duration for cognitive radio are derived under different signal to noise ratio (SNR)....
In this paper, taking the multipath spread of the channel into account, the performance of two-way amplify-and-forward relaying over Nakagami-m frequency-selective fading channels is analyzed. Based on the channel state information (CSI), the exact probability density functions of the received signal-to-noise power ratio (SNR) for semi-blind and channel state information assisted AF relaying are derived...
The long term evolution (LTE) system employs orthogonal frequency division multiple access (OFDMA) and single carrier frequency division multiple access (SC-FDMA) for the downlink and uplink transmission, respectively. However, in most existing literatures regarding the two-way OFDMA resource allocation, all terminals are assumed under an OFDMA operation, and the allocation scheme is always considered...
Spectrum sensing is a key feasible technology for cognitive radio (CR). Sensing time is an important sensing parameter which brings about a sensing-throughput tradeoff. In this paper, based on soft decision schemes, we investigate the sensing-throughput tradeoff problem and analyze the impact of different system parameters on the optimal sensing time for cooperative spectrum sensing. Simulation results...
We propose simple 2×2 MIMO 60-GHz RoF systems using single-electrode MZMs. Employing signal-signal beating interference mitigation, IQ imbalance compensation, and bit-loading technique, >40-Gbps OFDM signals over 12-km fiber and 3.5-m wireless transmission are achieved.
We experimentally demonstrate a 50-Gbps PDM-OFDM system with a direct-detection BLAST-aided receiver. Without dynamic polarization tracking, the PDM-OFDM system can achieve BER of 10-3 over all possible SOP with <;2.8-dB difference of OSNR requirement.
Recently, the concept of the cooperative communications has been applied extensively for the ultra-wideband (UWB) system. In this paper, the cooperative scheme of the noncoherent UWB impulse radio system with block-coded modulation (BCM) having a codeword matching and signal aggregation (CMSA) detection is discussed under different fading environments, which has not been studied yet. To enlarge the...
The amplify-and-forward protocol is a simple but effective relaying for cooperative communications systems because its associated relay node does not take encoding/decoding into consideration to re-transmit signals. However, the interference and multipath fades during the previous hop are also amplified. In this paper, based on the zero-forcing (ZF) concept, an adaptive amplification factor is investigated...
We propose a simple 60GHz RoF system using a single-electrode MZM with transmission distance improvement from 3km to 10km. With beat noise mitigation algorithm, SNR can be improved by up to 5.5dB.
We present a new MIMO precoding scheme using the LDL^H channel decomposition. The proposed method is verified to have lower complexity and better bit error rate (BER) performance than that of the conventional singular value decomposition (SVD). SVD is commonly used in decomposing the MIMO channel into parallel eigen-modes. However, the large variation of the singular values often leads to ill-conditioned...
To overcome the limitation of the transmit power spectral density, the cooperative communication in the ultra-wideband (UWB) differential transmitted reference system is studied. The amplify-and-forward is used as a relay protocol to re-transmit signals from multi-source terminals to one destination terminal. An adaptive amplification factor based on the channel information between relay and destination...
The conventional amplify-and-forward relaying protocol has less complex but worse performance than the decode-and-forward type. In the orthogonal frequency division multiplexing (OFDM) multihop relay systems, the system capacity can be enhanced via using the subcarrier permutation scheme at the relay terminals. However, under the multiuser scenario, one subcarrier may possess the best condition for...
Under the impact of multiuser interference, the exact bit error probability of the time-hopping ultra-wideband differential transmitted reference system over the Nakagami-m fading channels is evaluated via applying the characteristic function (CF) method. The CF method does not introduce any unrealistic assumptions, therefore our numerical results from the CF method demonstrate a better match in comparison...
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