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Cooperative communications enable single antenna mobiles in a multi-user environment to share their antennas and form a virtual multiple antenna array that allows them to achieve transmit diversity. In order to achieve improved diversity over the classical coded cooperation method in fading channels, we consider a coded cooperation diversity strategy that is suitable for multiple relays channels....
This paper investigates the performance of selection combining (SC) amplify-and-forward (AF) relaying with adaptive modulation to maximize the spectral efficiency. We derive the closed-form expressions of the average spectral efficiency and the outage probability of the proposed scheme over independent and non-identical Nakagami-m fading channels. The analysis results are verified by using Monte Carlo...
To meet the increasing demand for mobile broadband, multiple carrier features were subsequently introduced into UMTS Release-8 to Release-10. As a consequence, the UE capabilities of rejecting inter-stream interference have increased considerably. To fully utilize the UE capabilities and wireless resources, multi-point transmissions raised concerns in 3GPP High Speed Downlink Packet Access (HSDPA)...
Deployment of heterogeneous networks is one of the key technologies in LTE-Advanced. After low-power nodes were introduced to cellular system, great changes have taken place in the structure of traditional networks. Thus, range expansion (RE) scheme is proposed to adapt to these changes in the standardization process of heterogeneous networks. This paper studies the performance of heterogeneous networks...
Abstract-A cognitive radio (CR) network should have the ability to detect the presence of incumbent users and adjust its transmission in order to utilize unused licensed spectrum without causing interference to incumbent users. To effectively protect incumbent users, properly modeling expected interference from the CR system is therefore important.We model the accumulative interference generated from...
Block diagonalization (BD) algorithm is an efficient precoding technique for multiuser multiple-input multiple-output (MU-MIMO) system. In previous researches, BD precoding was mostly realized based on the singular value decomposition (SVD). However, in the cooperative transmission scenario where the dimension of channel matrix is significantly enlarged compared with the single base station (BS) transmission...
Abstract-Single and Multi-layer adaptive eigen based beamforming (EBB) has been proved to be a promising method to achieve the tradeoff between diversity and spatial multiplexing. But the CQI in multi-layer mode is calculated according to the CQI in single-layer mode. Lack of accurate multi-layer CQI will induce performance loss when implementing layer adaptation at eNodeB. In this paper, aiming to...
In real environments, channel reciprocity cannot be directly exploited between uplink and downlink in time-division duplex (TDD) due to antenna gain mismatch. Previous work about antenna calibration mainly focused on single cell. This work proposes an adaptive scheme for antenna calibration between two cooperative BSs. The proposed scheme aims at achieving an equal ratio between antenna transmitter...
Diversity is an effective technique to enhance link quality and increasing network capacity. In this paper, we propose a generalized distributed turbo codes (DTC)-based coded cooperation protocol for two-hop relay networks with an arbitrary number of relays. This scheme aims at achieving improved diversity over the classical coded cooperation method in Rayleigh fading channels. We develop a closed-form...
In cognitive radio networks, spectrum sensing is essential for the protection of primary users, enabling cognitive users to vacate channels immediately upon detection of primary users. In IEEE 802.22 standard, it is important to meet detectability requirements for in-band sensing, such as the maximum allowed probability of miss-detection and false-alarm. In this paper, we propose a periodic in-band...
In this paper, we propose a cooperative load balancing scheme focusing on improving effective resource utilization and mitigate the co-channel interference across domains through fair resource allocation in heterogeneous network (Het-Net). We models the load balancing issue as an optimization problem for minimizing the effective resource utilization. Simulation results have demonstrated that the system...
Device-to-Device (D2D) communication will become an important technology in future networks with the increase of the requirements of local communication services. The interference between cellular communication and D2D communication can be coordinated by proper power control and resource allocation. In this paper, we analyze the resource allocation methods for D2D communication underlaying cellular...
In this paper, we propose a simplified amplify-and-forward (AF) relaying scheme with adaptive modulation to maximize the spectral efficiency. We derive the closed-form expressions of the average spectral efficiency and outage probability of the proposed scheme over Rayleigh fading channels. The analysis results are verified by using Monte Carlo simulation. The numerical results demonstrate that the...
Transmit diversity can be regarded as a technology in wireless communication in order to enhance the system performance. Some relevant methods of transmit diversity have been presented on the basis of link-level research but do not consider multiple access interference (MAI) existing among users in the uplink of multi-user system. In this paper, we proposed one uplink transmit diversity scheme, which...
This paper considers the multiuser relay network, which applies Laneman's seminal protocol of selective decode-and-forward relaying. We mainly consider the opportunistic scheduling scheme which selects the user who has the largest received signal-to-noise ratio at the destination for transmission. We derive the exact and asymptotic expressions for the outage probability under Rayleigh fading, and...
In order to solve the problem that the existing resource allocation strategies cannot give integrative consideration to QoS, spectrum efficiency for mixed traffic, this paper proposes a utility-based resource allocation algorithm for mixed traffic in wireless networks. The unified utility function for users with different traffics is studied first. After that, the optimization model for the resource...
A cognitive radio (CR) system should have the ability to detect the presence of incumbent users and adjust its transmission so that it can utilize unused licensed spectrum without causing interference to incumbent users. To effectively protect incumbent users, properly modeling the expected interference from CR system is therefore very important. We model the accumulative interference generated from...
This paper investigates a novel relaying strategy for cooperative networks over Nakagami-m fading channel, namely selection incremental relaying (SIR), which combines selection relaying (SR) with incremental relaying (IR) based on decode-and-forward (DF). The closed-form expression for the outage probabilities of both single relay and opportunistic relay strategies are derived. Simulation results...
The virtual MIMO (V-MIMO) and coordinated multipoint transmission (CoMP) are adopted by the LTE system to extend the uplink spectral efficiency. V-MIMO makes use of spatial multiplexing to increase system throughput while CoMP by means of mitigating inter cell interference (ICI) significantly achieve the same effect. In this paper, we present an orthogonality based proportional fair scheduling (OPF)...
Femtocells are designed to cover a short range of area and improve the cellular system capacity in an economically viable way. In this paper, we propose an adaptive sub-band allocation (ASA) scheme for the downlink transmission of the LTE system, which consists of orthogonal sub-band assignment (OSA) algorithm and adaptive sub-band reuse (ASR) algorithm based on the interference graph. The interference...
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