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In order to reduce MAP overhead for periodic small-sized services such as voice over IP (VoIP) service, a persistent scheduling scheme has been proposed in IEEE 802.16e/m. Although this persistent scheduling scheme is designed for periodic services, we propose to adopt the persistent scheduling for non-periodic real-time services with small-sized packets by considering the advantage of MAP overhead...
This paper considers the use of predefined frequency-domain power profiles in downlink LTE-A aiming at making interference predictable across the Physical Resource Blocks, to be combined with fair resource allocation. In particular, the power profile structure is defined depending on the position of the users and fairness-oriented scheduling strategies are considered. Evaluations of the throughput...
The Physical Downlink Control Channel (PDCCH) is used to signal dynamic resource assignment information in the Long Term Evolution (LTE) system. In the presence of numerous active users, the system performance is likely to be hindered by shortage of control channel resource. In this paper, several simple algorithms are brought forward for making efficient PDCCH resource allocation. We first propose...
Block diagonalization is a linear precoding technique which eliminates the multi-user interference at the transmitter side by creating parallel orthogonal single user links. In this technique, the transmit diversity order is fixed for each user and only power can be controlled to satisfy SINR requirements. This restricts the degrees of freedom available for resource allocation and limits the energy...
Orthogonal Frequency Division Multiplexing (OFDM) is very sensitive to carrier frequency offsets (CFO). The CFO results in intercarrier interference (ICI). This drawback of OFDM is inherited to Orthogonal Frequency Division Multiple Access (OFDMA). In this paper, we propose a new ICI model for an uplink OFDMA system that takes into account the presence of the cyclic prefix which is usually ignored...
Careful management of inter-cell interference is important in OFDMA based systems such as LTE. In this paper, we study an uplink ICIC (Inter-cell Interference Coordination) mechanism, which fully utilizes the flexibility of frequency selective scheduling and rate adaptation, while dynamically limiting the interference experienced by the neighboring cells. This technique can be seen as an extension...
In Cognitive Radio Networks (CRN), nodes can switch to different operating frequency bands and adapt their transmission power levels such that Cognitive Radio (CR) nodes transmissions remain transparent to the Primary Radios (PR). This constraint can be assured by keeping the aggregated interference caused by CR transmissions at PR nodes location below a defined threshold. In this paper, we propose:...
Due to the license-exempt nature of the cognitive radio (CR), multiple CR networks may operate (coexist) on the same channel. In this paper, we first discuss some techniques for self-coexistence of CR local and personal area networks, where the self-coexistence means the coexistence of homogeneous CR networks using the same PHY/MAC protocol. Then, we propose a self-coexistence etiquette for the ECMA...
Bit-Power Loading (BPL) algorithms are proposed based on Effective SINR Mapping (ESM) techniques. The ESM techniques used are the Exponential ESM (EESM) as well as the Mean Mutual Information per Bit (MMIB). The algorithms are based on proper usage and modifications of algorithms already proposed in the literature, applied to ESM compatible link-level performance models. The performance gain when...
Amplify-and-forward (AF) is one of the most common and simple approaches for transmitting information over a cooperative multi-input multi-output (MIMO) relay channel. It has recently been demonstrated that the spectral efficiency of AF scheme can be maximized by using the relay as a smart precoder. However, source node precoding has not been included in the overall maximization problem. In this paper,...
In uplink 3GPP Long-Term Evolution (LTE), single-carrier frequency division multiple access (SC-FDMA) is considered partly because of the fact that Peak-to-Average Power Ratio (PAPR) for Multi-Carrier Orthogonal Frequency Division Multiplexing (MC-OFDM) is still a hindrance. But, an unique characteristic of SC-FDMA is that subcarriers have to be assigned by contiguous manner for a specific user, which...
Layered Steered Space-Time Codes (LSSTC) is a recently proposed multiple-input multiple-output (MIMO) system that combines the benefits of vertical Bell Labs space-time (VBLAST) scheme, space-time block codes (STBC) and beamforming. We suggest a new downlink scheme employing LSSTC with optimal power allocation, by assuming that the user feeds the BS with the average SNR per VBLAST layer through the...
For multiple-input multiple-output (MIMO) wireless communication system with minimum mean square error (MMSE) detection, power allocation between pilot and data symbols is investigated under MMSE channel estimation in this paper. We first propose a novel soft-output MMSE MIMO detector by taking the channel estimation error into consideration. Then, by random matrix theorem, we propose an effective...
In this paper, we propose a double space-time transmit diversity (DSTTD)-based two-path relay system with power allocation and link combining methods. The two-path relaying protocol can restore spectral efficiency decreased due to the half-duplexing at the relay nodes and the DSTTD method can appropriately achieve the diversity gain from the two paths. To circumvent severe performance degradation...
In current cellular networks base stations (BSs) usually perform independent scheduling without coordinating the resource allocation among different cells. This, however, often leads to high interference levels in cellular networks operating with universal frequency reuse, such as the 3GPP UTRAN Long Term Evolution (LTE). Coordinated scheduling between different BSs may mitigate this problem by taking...
This paper considers a distributed power allocation scheme for sum-rate-maximization under cognitive Gaussian multiple access channels (GMACs), where primary users and secondary users may communicate under mutual interference with the Gaussian noise. Formulating the problem as a standard nonconvex quadratically constrained quadratic problem (QCQP) provides a simple distributed method to find a solution...
In this paper we propose a novel technique for efficient video distribution over WiMAX networks. The technique incorporates resource distribution, scheduling and content-aware streaming of video taking advantage of a flexible QoS functionality offered by WiMAX. The proposed technique was thoroughly investigated using NS-2 software package under various real-life scenarios which included streaming...
In this paper we introduce a resource allocation algorithm based on location information for cognitive radio systems. The location information allows a practical implementation of cognitive radio systems when the channel state knowledge of the interference links with the primary users is not available. Using this information and measurements, the secondary users estimate the pathloss between the secondary...
In this paper, we propose user grouping algorithms to provide power minimization in grouped STBC MC-CDMA systems. Depending on the channel fading conditions, power control is utilized to minimize the total transmitted power under a BER constraint. When the allocation is performed without a fair data rate requirement, we provide the optimal solution to the minimization problem. However when some fairness...
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