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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...
The opportunistic beamforming (OB) technique in multicellular OFDMA networks is investigated in this paper. For this reason, three cross-layer radio resource management (RRM) algorithms for OFDMA operational scenarios that are based on typical resource allocation targets such as minimization of transmit power, maximization of throughput and interference averaging are considered. The OB concept is...
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...
Interference problems in cochannel femtocell networks may cause significant performance degradation for certain femtocell/macrocell users. These problems and potential solutions are recently being investigated within the 3GPP. The goal of the present paper is to review the simulation framework for femtocell networks in 3GPP and briefly summarize some of the important inter-cell interference coordination...
Reducing the consumed energy in wireless communication systems has a direct impact on operational expenditure as well as CO2 emissions. With increasing interest in multimedia applications and high data rate services, environmentally sustainable communications networks must reduce the energy per delivered bit at an equal rate, if not better. This paper addresses downlink energy-efficient transmission...
In this paper we describe an LTE based demonstrator of the Universal Link Layer API (ULLA) and Cognitive Resource Manager (CRM) modules that are developed in ARAGORN project. The demonstrated LTE system comprises one LTE TDD eNode B and one User Equipment (UE). We first introduce ULLA and CRM framework and then demonstrate their suitability to be implemented with the existing LTE equipments. We show...
In this paper, we apply distributed optimization dynamics of the mutually connected neural networks to RAN selection in heterogeneous type cognitive wireless networks. We evaluate the performance of the proposed approach by implementing it on an experimental heterogeneous wireless network system called Cognitive Wireless Cloud, which supports vertical handover between different radio access networks...
Cognitive wireless mesh networks have great potential to green communication. One of the critical challenges for realizing such networks is how to adaptively match transmit powers and allocate frequency resources among secondary users of the licensed frequency bands whilst maintaining the quality-of-service (QoS) requirement of the primary users, even in mutually entangled interferences environment...
A novel cell architecture based on Distributed Antenna Arrays for next generation mobile WiMAX systems is proposed. By exploiting Spatial Multiplexing and beamforming techniques, our target is to maximize the throughput of a high speed user by keeping low the deployment costs. Radio over Fiber is one of the best solutions to feed from a central point distributed arrays and share wireless resources...
This paper proposes a slot-based persistent allocation scheme which allows WiMAX base stations (BSs) allocating resources to VoIP-like traffic in an efficient way. The proposed scheme firstly scans resource slots within the stream of data frames to identify an available resource slot for a persistent resource allocation. To facilitate the scanning process, the base station maintains a tree structure...
Attention to resource allocation algorithms for multiservice Code Division Multiple Access CDMA networks has focused on algorithms maximizing the uplink aggregate throughput. In the present paper we address the problem of the joint power and spreading factor (SF) allocation to non real-time (NRT) terminals on the uplink, once real time constraints are satisfied. An optimal algorithm is proposed, that...
The race toward higher throughputs for cellular network users is getting more difficult everyday. On the one hand cellular network operators wish to increase benefits by offering new services to users, but on the other hand spare radio resource are shrinking away. The spreading of WiFi-3G dual mode devices is making this fight even harder. The new ”Femtocell” technology is expected to be the rescuer...
This paper considers the downlink of a cellular orthogonal frequency division multi-access (OFDMA) system, in which multiple base stations (BSs) are coordinated by a centralized resource allocation algorithm. We address the problem of maximizing the weighted sum of the minimal user rates (WSMR) of coordinated cells subject to a total power constraint at each BS. In particular, the solution of this...
In orthogonal frequency division multiple access (OFDMA) systems, efficient resource allocation is very important to improve the performance of the OFDMA system. The general principle of resource allocation in an OFDMA system is to assign each subcarrier to the user with the best channel condition for that subcarrier. However, in delay tolerant traffic, current work did not consider that packets on...
This paper presents an efficient and fair uplink resource allocation algorithm in multicarrier based cognitive radio systems. The proposed resource allocation is divided into two steps. The subcarriers to user assignment is first performed and then the power is allocated to the different subcarriers. The subcarriers are allocated based on the channel quality, amount of interference imposed to the...
Game theory provides an adequate methodology for analyzing topics in communication systems that include trade-offs such as the subject of load balancing. As a means of balancing the load in the network, users are handed over from highly loaded cells to lower loaded neighbors increasing the capacity usage and the Quality of Service (QoS). The algorithm that calculates the amount of the load that each...
Fractional frequency reuse for the downlink of multicellular WiMAX networks is examined in this work. Three different schemes are evaluated through simulations, including distance-based and SINR-based approaches, as well as a new scheme which is based on load-balancing between different reuse regions. The proposed load-balancing scheme overcomes the main weakness of the SINR-based approach, namely...
In this paper, a joint channel-and-queue-aware relay selection and resource allocation scheme at the scheduling phase in an OFDMA downlink cellular network is proposed. The scheme can choose the best relay to cooperate and allocate subchannels and power for the source and the relay for the selected packet which can maximize the proposed utility function waiting in the base station. Under the premise...
In this paper, we focus on the guarantee of inter-cell fairness in OFDM femtocell systems. To solve this problem, we formulate an optimization problem to maximize the summation of logarithmic cell capacity. Based on analytic results, we propose an enhanced modified iterative water-filling algorithm which improves inter-cell fairness compared to a modified iterative water-filling algorithm. The key...
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