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This paper studies user-centric cluster scheme in cloud radio access network (Cloud-RAN), where distributed Radio Remote Heads (RRHs) are connected to a centralized Based Band Units (BBUs) pool and all baseband processing is performed via high-bandwidth low-latency backhaul network. In user-centric cluster scheme, BBU schedules multiple RRHs for each user to form the serving cluster, and then BBU...
This paper presents the performance of scheduling for adaptive modulation and coding based on the dynamic margin control. To cover various wireless channel conditions and requirements for multimedia traffic QoS, the selection of suitable MCS (Modulation and Coding Scheme) is important technique in real deployment and management fields. In this paper, we propose dynamic margin control schemes based...
In Heterogeneous Networks (HetNets), Almost Blank Subframe (ABS) can provide interference free communication to the Cell Range Expansion (CRE) area users. Although the CRE technique is simple and guarantees a better offloading, it might not be the best way for balancing the load. In this paper, we investigate the joint optimization of the user association and the ABS ratio computation. We propose...
In cellular networks Device to Device (D2D) communication is used to improve the resource utilization and the throughput. SNR Based Master-Slave Dynamic D2D Communication Algorithm (SMSDCA) is proposed to improve the resource utilization of the cellular network and improved Quality of Service (QoS). It is achieved by allocating some User Equipment (UE) as master in that cluster based on SNR and energy,...
A joint channel assignment and power allocation algorithm is presented for cognitive wireless networks, where primary and secondary users operate over the same frequency band at the same time. In this study, we take into consideration a constraint on the interference from secondary users towards primary users, as well as a constraint on the QoS of secondary users. The problem is formulated as a constrained...
This paper studies quality-of-service (QoS)-aware frequency provisioning schemes for a downlink multi-user multi-carrier system in a frequency-selective fading environment with diverse user-QoS requirements in terms of target delay and effective capacity (EC). Since a jointly optimal power and sub-carrier allocation requires an exponential-time exhaustive search, we explore an alternative simpler...
Device-to-device (D2D) communications as an underlaying LTE-Advanced network has proven to be efficient in improving the network performance and releasing the traffic load of eNodeB. By sharing radio resource with cellular user equipments (CUEs), D2D communications can significantly enhance the overall spectral efficiency. However, the resulting mutual interference may cancel or even outweigh the...
With enormous growth in the telecommunication industry, energy efficiency has become a critical issue. Base stations and the core network account for a large amount of energy consumption today. Traditional energy saving techniques switch some base stations off completely during light loads to save energy. This creates problems for the backhaul network and also for quickly returning to full capacity...
As it becomes common for wireless service providers (WSP) to employ multiple heterogeneous radio access technologies (RAT), the management of the combined resources across multiple RATs arises as an important issue. The WSP's objective is to assign different users to the different RATs so as to maximize network capacity (or total utility) while ensuring that individual users' quality of service (QoS)...
In this paper, we propose a cross-layer dynamic CQI resource allocation (DCRA) scheme for OFDMA systems. Implemented at the base station (BS) side, DCRA algorithm chooses adaptively the mobile stations (MS) which are to send feedback to maintain their QoS constraints. Based on the channel quality indicator (CQI), feedback rate for each MS is determined exploiting the signaling of MAC layer automatic...
The power control problem is considered with the CR user QoS requirement and the interference to primary user under the threshold which the primary user can tolerate. We model the power control as a optimize problem which each CR user SINR must not less than minimum SINR requirement and the total interference must less than predefined threshold. Firstly we consider the network can satisfy the CR user...
In this paper, we investigate the optimization problem of resource allocation in downlink of multiuser MISO-OFDM system. Multiple users with different BER and minimum transmission rate requirements are considered. We propose a novel heuristic allocation algorithm (HAA) of radio resource, which minimizes the total transmit power of the base station while meeting individual users'QoS requirements. The...
In order to reduce the co-frequency interference for multi-cell OFDMA system, a multi-cell dynamic subcarrier allocation scheme was proposed for downlink orthogonal frequency division multiple access (OFDMA) cellular system. The proposed scheme reduces the powers of co-frequency users, which matches access control to maximize the distances between co-frequency subcarriers users. As a result, the proposed...
Orthogonal frequency division multiplexing (OFDM) is the key component of many emerging broadband wireless access standards. The resource allocation in OFDM uplink, however, is challenging due to heterogeneity of users' quality of service requirements, channel conditions, and individual resource constraints. We formulate the resource allocation problem as a non-strictly convex optimization problem,...
In this paper we consider cognitive radios (CR) that employ orthogonal frequency division multiplexing (OFDM) modulation at the physical layer and present an algorithm for transmitter adaptation subject to specified quality of service (QoS) constraints. The proposed algorithm explicitly considers multipath channels between the CR transmitter and its intended receiver, and performs joint spectral shaping...
We present improved SNR-based packet scheduling (I-SPS) algorithm as an extension of SPS algorithm. In I-SPS, the connection with better channel condition will be assigned higher weight in scheduling and the connection suffered burst error will be compensated by increasing its weight after its channel condition becomes good. Theoretical analysis and simulation results demonstrate that I-SPS algorithm...
In order to improve the QoS in the cell edge of broadband cellular systems, we propose to modify the proportional fair (PF) scheduling algorithm in a new way. In the traditional PF algorithm, a beta parameter can be used in the denominator to control the PF ratio. In our method, the beta is dynamically adjusted in a time and user depended basis, taking into account for example, the user's receiving...
The joint power and admission control problem is considered for a cognitive underlay scenario, under Quality of Service (QoS) constraints for both primary and secondary users. Primary users must be guaranteed a premium service rate, measured by their signal to interference plus noise ratio (SINR); secondary users, if admitted, should be provided with at least a basic service rate, and the number of...
This paper investigates effects of pilot assisted channel estimation on dynamic resource allocation in a multiuser orthogonal frequency division multiplexing (OFDM) system. The channel estimation is done in each OFDM symbol through least-squared error (LSE) or minimum mean-squared error (MMSE) algorithm. The performance of each of these algorithms is evaluated through computer simulations. The maximal...
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