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Multiple-Input Multiple-output (MIMO) has great potential for improving the throughput of Wireless mesh networks (WMNs). MIMO can increase network throughput via suppressing interference from neighboring links and/or allowing transmission of multiple independent data streams over MIMO antenna elements. However, these throughput gains are limited unless higher layer protocols also exploit these capacities...
We present a cognitive MIMO wireless communication system with cognitive link and primary link using multiple transmission antennas. Gamma distribution function is used to obtain accurate approximation to signal-to-interference-and-noise ratio (SINR) of cognitive link, and new closed-form expressions of the outage probability are derived in two scenarios. Furthermore, how much influence of detection...
User scheduling and multiuser multi-antenna (MU-MIMO) transmission are at the core of high-rate data-oriented downlink schemes of the next-generation of cellular systems (e.g., LTE-Advanced). Scheduling selects groups of users according to their channels vector directions and channel quality indicator (CQI). However, when scheduling is applied independently in each cell, the inter-cell interference...
Coping with collisions is one of the biggest challenges in the design of MAC algorithms for wireless networks. Recent advances in MIMO communications have provided the possibility of decoding colliding packets. In this paper, we introduce a new MIMO cross-layer MAC/PHY design that is capable of combating collisions through the use of a multiple packet detection technique. Analytical and simulation...
The 3GPP LTE standard for mobile broadband includes multi-antenna transmission modes that improve performance, both in terms of coverage, spectral efficiency and peak throughput. The antenna system design, both at the eNB and at the UE is critical to a well performing system; it should be designed with the intended performance profile in mind. Field trials were performed in order to investigate the...
In this paper, a framework of opportunistic beamforming for multiuser MIMO downlink employing rateless codes is considered. By exploiting the benefits of a combination of opportunistic beamforming and rateless codes, the system performance is obviously improved while guaranteeing QoS requirement, such as maximum average delay. It is proved that, in order to satisfying delay constraint, the maximum...
The results of a field trials campaign in a park, a wide street, a narrow street and office environments are presented in this paper. The trials are carried out using a real time 4×4 MIMO-OFDM testbed working in the 2.4 GHz ISM band and a 20 MHz bandwidth. The testbed supports both spatial multiplexing and transmit and receive diversity. We compare the system performance using different number of...
In this paper, we investigate the relaying scheme for multi-antenna cooperative networks without channel state information at the transmitters. It is shown that the classic opportunistic relaying scheme, which allows only one relay node to forward the message, may lead to significant loss when it is extended to the corresponding multi-antenna relay scenarios. A generalized opportunistic relaying approach,...
MIMO links enable concurrent transmissions of multiple independent data streams between a pair of nodes, which can significantly improve network throughput. In this paper, we study the stream control and scheduling problems in multihop wireless networks with MIMO links. We present a constant factor approximation algorithm as well as an efficient heuristic algorithm for stream control. Moreover, we...
This paper considers multiple-input/multiple-output(MIMO) cooperative communication systems with a decode-and-forward (DF) relay. We propose novel rate maximization schemes which utilizes uniform channel decompositions (UCD)to decompose the MIMO channel between a base station (BS) and a relay station (RS). In the proposed scheme, the MIMO channel is decomposed into multiple independent subchannels...
User scheduling and multiuser multi-antenna (MU-MIMO) transmission are at the core of high-rate data-oriented downlink schemes foreseen in the next-generation cellular systems (e.g., LTE-Advanced). Scheduling exploits the knowledge of the users' instantaneous achievable coding rates. However, when it is applied independently in each cell, the level of inter-cell interference (ICI) experienced by each...
The recently approved 802.11n standard establishes the integration of MIMO technology in WLANs with the goal of achieving high data rates. However, it does not exploit the multiuser capabilities of the MIMO channel. In this paper we present a multiuser downlink transmission scheme that combines low-complexity beamforming at the Physical layer with an opportunistic channel-aware MAC scheduling policy...
MISO-OFDM systems enable the allocation of resources in the frequency and spatial domain to increase the data throughput of wireless systems. In this paper, we initially present a near-optimal solution to the MISO-OFDM Resource Allocation (RA) problem. This solution performs an exhaustive search over all possible user sets and then uses a dual-based approach to optimally assign power to the selected...
In this paper, we propose a generalized multiple-input multiple-output (MIMO) transmit preprocessing system, where both the channel coding and the linear MIMO transmit precoding components exploit the knowledge of the channel. Moreover, we also propose a novel technique, hereby referred to as pilot symbol assisted rateless (PSAR) coding, where a predetermined fraction of binary pilot symbols is interspersed...
In this paper, we present a novel 128/256-point FFT/ IFFT processor for the applications in IEEE 802.16e based on MIMO-OFDM. The pipeline FFT architecture is proposed to efficiently deal with 1-4 multiple data sequences, and increase the throughput. Furthermore, less hardware complexity is needed in our design compared with conventional individual parallel approach. The signal-to-quantization noise...
This paper proposes a novel solution to cross-layer optimization for streaming of image/video over adaptive MIMO-OFDM wireless networks. Joint source-channel coding (JSCC) that includes progressive coding and adaptive modulation/code set (MCS) is applied to a singular value decomposition (SVD)-based MIMO-OFDM transmission system. Armed with a packet error rate (PER) model that considers modulation,...
Lattice-reduction (LR)-aided successive interference cancellation (SIC) is able to achieve close-to optimum error-rate performance for data detection in multiple-input multiple-output (MIMO) wireless communication systems. In this work, we propose a hardware-efficient VLSI architecture of the Lenstra-Lenstra-Lovász (LLL) LR algorithm for SIC-based data detection. For this purpose, we introduce various...
In this paper, a VLSI architecture of a reduced-complexity K-best sphere decoder is designed, which aims to solve the 4 × 4 64-QAM multiple-input multiple-output (MIMO) signal detection problems in high-speed applications. We propose a fully-pipelined sorter, which can generate one result per clock cycle and thus greatly enhance the detection throughput. On the other hand, various K values are adopted...
This paper presents a VLSI architecture of a novel soft-output K-Best MIMO detector. The proposed detector attains low computational complexity using three improvement ideas: relevant discarded paths selection, last stage on-demand expansion, and relaxed LLR computation. A deeply pipelined architecture for a soft-output MIMO detector is implemented for a 4×4 64-QAM MIMO system realizing a peak throughput...
This paper presents a low power VLSI implementation of a novel Multiple-Input Multiple-Output (MIMO) decoder which combines Fixed Complexity Sphere Decoder (FSD) algorithm, real-valued lattice formulation and Pair-wise sorted QR decomposition (P-SQRD) searching approach to simultaneously improve the throughput, bit error rate (BER) and complexity. Two-stage approximate sorting scheme with minimum...
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