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A soft-input soft-output non-coherent detection algorithm is proposed for multi-antenna systems, where differential space-time block code is employed. The proposed algorithm aims to calculate a posteriori probabilities of the information bits by means of forward and backward message passing of the BCJR approach. The proposed algorithm can exploit the soft information effectively with the aid of the...
In this paper, two near-optimal detectors based on the convex optimization algorithm are proposed for multiuser detection (MUD) in the ultra-wide bandwidth (UWB) systems. The first detector performs semidefinite relaxation (SDR) to approximate the optimum multiuser detection (OMD) which is a nondeterministic polynomial time hard (NP-hard) problem. When the cutting planes generation algorithm is employed...
In this paper, semidefinite relaxation (SDR) technology is exploited for the multiple-symbol detection (MSD) over the multiple-input multiple-output (MIMO) ultra-wideband (UWB) systems. The existing scheme generalized likelihood ratio test (GLRT) MSD jointly detect multiple symbols, however, it entails a complexity of O(2M), where M is the observation window size. To this end, SDR is employed to reformulate...
An ultra-high data rate Time Reversal (TR) Multiple-Input Multiple-Output (MIMO) Ultra-Wideband (UWB) communication system with space-time pre-equalizer is proposed. When the symbol duration is set to approach the duration of UWB monocycles, the data rate is close to the limit due to the extremely large bandwidth, resulting in the severe intersymbol interference (ISI). The zero-forcing (ZF)criterion...
In this paper, we investigate noncoherent Multiple-Input Multiple-Output (MIMO) ultra-wideband (UWB) systems where the signal is encoded by Differential Space-Time Block Code (DSTBC). Considering the specific signal format of DSTBC-UWB system and employing the property of DSTBC, a noncoherent multiple symbol detection (MSD) scheme is developed by generalized likelihood ratio testing (GLRT) approach...
By introducing the leakage concept, the maximum signal-to-leakage-and-noise ratio (SLNR) scheme has been served as a candidate precoding scheme in the advanced long term evolution (LTE-Advanced) communication system. However, the original scheme allocates every user the same transmit power and takes the matched filter to decode the receive signals, which results in the limited bit error rate (BER)...
A multi-layer orthogonal block coded transmission scheme is proposed in this paper to enhance the performance of the noncoherent Ultra-Wideband impulse radio (UWB-IR) system. The design employs a novel Multiple Orthogonal Block Coded Modulation (MOBCM), which transmits multiple information bearing orthogonal codewords with an ingenious layered structure. At the receiver side, a correspondent noncoherent...
In this paper, we propose a decode-and-forward (DF) two-way relay ultra-wideband (UWB) network with a joint-demodulated non-coherent receiver to boost the system throughput. We consider a three nodes relay network with two terminals exchanging information via a relay node during two time slots. After jointly detecting the simultaneously arrived signals, the relay node broadcasts the XORed signal to...
In this paper, we proposed an effective and unified transmit power allocation (TPA) scheme for the Singular Value Decomposition (SVD)-Assisted multi-user multiple-input multiple-output (MU-MIMO) downlink (DL) and uplink (UL) transmissions in the presence of imperfect channel state information (ICSI). The existing power allocation policies for the SVD-Assisted MU-MIMO system, such as equal power allocation...
In this paper, we investigate the Singular Value Decomposition (SVD)-Assisted multi-user multiple-input multiple-output (MU-MIMO) downlink transmission in the presence of imperfect channel state information (ICSI), and propose an effective transmit power allocation (TPA) scheme. The original equal power allocation (EPA) has been adopted in perfect CSI case. However, EPA doesn't exploit the CSI and...
Synchronization is a crucial task and big challenge for ultra-wideband (UWB) systems, especially in the presence of inter-symbol interference(ISI) and inter-frame interference (IFI). This paper proposes a blind synchronization and demodulation algorithm that is capable of mitigating ISI and IFI for noncoherent UWB system. Employing a series of codeword matching and averaging operations, the proposal...
In this paper, a joint blind synchronization and demodulation scheme is developed for ultra-wideband (UWB) impulse radio systems. Based on the prior knowledge of the direct-sequence (DS) spread codes, the proposed approach can achieve frame-level synchronization with the help of frame-rate samples. Taking advantage of the periodicity of the DS spread codes, the frame-level synchronization can be carried...
In this paper, a novel synchronization algorithm dispensing with searching is proposed for UWB communications. By adopting a stream of alternating orthogonal pulses, frame-level synchronization can be achieved without training sequence involved. Without any searching procedure, the timing offset estimator is obtained in a closed form, therefore considerably reducing the synchronization time. Simulations...
Relying on judicious training symbols, we can construct a redundance-included demodulation template (RDT) from the received signal. When the RDT is available, there are two approaches to select. One is to demodulate transmitted symbols directly by the RDT, which does not require timing acquisition, and thereby has considerably lower complexity. The alternative is to first acquire the timing offset...
In this paper, two novel space-time coded modulation and corresponding noncoherent detection schemes for Ultra-Wideband (UWB) impulse radio system are proposed. An additional orthogonality is introduced to original Orthogonal Space-Time Block Code (OSTBC) for performance enhancement in the proposed two schemes, which is termed as Dual Orthogonal Space-Time Coded Modulation (DOSTCM). The specially...
In this paper, a blind two-step synchronization algorithm is proposed for direct-sequence (DS) ultra-wideband (UWB) communication systems. In the first step, the start of individual frames is estimated via simple square, overlap-add operation and energy detection technique. Then the first frame in each symbol is identified by exploiting the randomicity of DS codes and information symbols at the second...
This paper proposes a novel detection scheme based on Dempster-Shafer (D-S) evidence theory in multiple-input multiple-output (MIMO) systems. The focal-element-set (FES) characterizes the uncertainty contained in the decision statistics, and the corresponding basic-probability-assignment (BPA) of FES is the likelihood measure, acting as the soft-decisions of the transmit signals. The uncertainty can...
This paper proposes a novel bit-level combining scheme based on Dempster-Shafer (D-S) evidence theory, termed DS combining, for multiple-input multiple-output (MIMO) systems with hybrid-automatic-retransmission-request (HARQ) mechanism. The DS combining is assisted by the proposed DS detection for performance improvement. The focal-element-set (FES) characterizes the uncertainty contained in the decision...
One of the biggest challenges in ultra-wideband impulse radio (UWB-IR) is timing acquisition. To accomplish synchronization, a novel modulation scheme is presented in this paper. Relying on the unique signal structure and the first order- statistics of the received signal, the timing offset can be acquired by energy detection even if in the presence of inter-frame interference (IFI) and inter-symbol...
One of the biggest challenges in ultra-wideband (UWB) communications is the accurate and rapid timing acquisition for the receiver. This paper presents a timing acquisition scheme dispensing with searching for UWB communications. Without training sequence involved, timing offset parameter is estimated by exploiting a stream of alternating orthogonal pulses, and frame-level synchronization can be achieved...
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