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In this paper, it is proposed an algorithm to allocate resource blocks for Long Term Evolution (LTE) communication systems where it is taken into account the maximum delay guarantee and Modulation and Coding Scheme (MCS) restrictions of the downlink transmission. The proposed algorithm considers the channel quality and the delay target value for each user in order to decide on the scheduling of available...
To deal with problems that queuing information is not included in cognitive information when performing Resource Allocation (RA), a dynamic cross-layer scheme is proposed for the multimedia cognitive radio (CR) system with Orthogonal Frequency Division Multiplexing (OFDM). In this scheme, we consider that several crucial factors influence the RA decision, including channel state information, interference...
In this paper we propose an algorithm to achieve hard delay constraints in OFDMA systems. The resource scheduler has to ensure that delay deadlines of the packets get achieved and the resources are also not under utilized. This is a very difficult task since the channel and packet arrival in user queues are time varying in nature. The instantaneous decisions of scheduler depend on current as well...
In this paper, we study the cross-layer resource allocation for the secondary users (SUs) supporting heterogeneous services in interference-limited spectrum sharing system. Two classes of SUs are considered: delay-tolerant SUs (DT-SUs) and delay- sensitive SUs (DS-SUs). With the queue theory, the delay requirements of DS-SUs are transformed into constant rate requirements. Unlike most previous works,...
The proposed resource allocation scheme can boost the spectral efficiency of multi-user OFDMA wireless systems with heterogeneous delay requirements. The existing designs usually have two important assumptions that the users are delay insensitive and Channel State Information at the Transmitter (CSI) is perfect. In practice, users have heterogeneous delay requirements and CSI usually becomes outdated...
One of the fundamental requirements of state-of-the-art and next-generation OFDMA-based wireless communication systems is the provision of quality of service (QoS) guarantees. This paper addresses the design of cross-layer channel-and queue-aware scheduling and resource allocation algorithms jointly assigning transmission data rates, bandwidth and/or power to active users while providing support to...
CoMP (Coordinated Multiple Point transmission) is being discussed in 3GPP (3rd Generation Partnership Project) to improve the cell edge performance as well as the total cell throughput of mobile systems. In this paper, we focus on the control architecture to realize downlink CoMP JT (joint transmission) with inter eNB (evolved NodeB) coordination. We have designed the control architecture with a distributed...
Besides avoiding inter-symbol interference and leading to high capacity, wireless orthogonal frequency division multiplexing (OFDM) provide fine granularity for resource allocation since they are capable of dynamically assigning sub-carriers to multiple users and adaptively allocating transmit power. The current dominate layered networking architecture, in which each layer is designed and operated...
Long Term Evolution (LTE) is considered one of the main candidate to provide wireless broadband access to mobile users. Among main LTE characteristics, flexibility and efficiency can be guaranteed by resorting to suitable resource allocation schemes, in particular by adopting adaptive OFDM schemes. This paper proposes a novel solution to the sub-carrier allocation problem for the LTE downlink that...
This paper studies QoS-guaranteed fair resource allocation and packet scheduling for OFDMA networks. We start with non-traffic-aware weighted generalized proportional fair (WGPF) scheduler and make it a delay-fair scheduler. Delay-fair objective is to equalize delay dissatisfaction measures among users. In this paper the focus is on mean queuing delay. We show how the WGPF objectives are connected...
Orthogonal frequency division multiplexing (OFDM) communication systems require accurate estimation of timing offset and channel impulse response in order to achieve desirable performance. In this paper, we consider the optimal placement of pilot symbols over the OFDM subcarriers in order to minimize a function of the Cramér-Rao bound on these parameters. Previous work has investigated this problem...
In this paper, the packet combining technique in the downlink OFDMA system is introduced in conjunction with frequency diversity to enhance the reliability of retransmissions and thus reduce the large time delay caused by retransmissions. The novel retransmission technique aims to reduce the maximum number of retransmissions for failed packets, while maximizing the throughput. A suboptimal algorithm...
In this paper we study the performance of a SC-FDMA cellular system when a complete Inter-Cell Interference (ICI) management strategy is implemented. We also introduce a novel sector-and-zone frequency ICI coordination scheme, derived from Fractional Frequency Reuse (FFR), which succeeds on increasing the capacity of an SC-FDMA cellular system. Working together with open-loop Fractional Power Control...
Scheduling is a fundamental component in resource (bandwidth and power) management in NG wireless networks and plays the main role in providing QoS requirements such as delay, throughput and packet loss for different classes of service in 802.16d networks. In this paper we propose a novel scheduling algorithm Strict Priority Based Adaptive modulation and Coding (SP_AMC_Based) that can grantee QoS...
Multiuser diversity combined with Orthogonal Frequency Division Multiple Access (OFDMA) are a promising technique for achieving high downlink capacities in new generation of cellular and wireless network systems. The total capacity of OFDMA based-system is maximized when each subchannel is assigned to the mobile station with the best channel to noise ratio for that subchannel with power is uniformly...
In this paper we propose three different frequency resource management strategies that, working together with FFR and open-loop Fractional Power Control (PFC), succeed on mitigating both uplink inter-cell interference (ICI) and ICI fluctuations, that usually reduce the performance of SC-FDMA cell-based systems. Simulations are carried out with real-time traffic patterns at different loading scenarios,...
A multichannel scheduling based on an extension of modified largest weighted delay first (M-LWDF) scheduling is proposed for heterogeneous traffic. We consider the downlink of an orthogonal frequency division multiplexing (OFDM) system where the wireless channel and queue state information are taken into account to schedule delay-sensitive and ratesensitive traffic. We propose a logarithmic notion...
In this paper, we propose a channel aware fast utility-based algorithm for allocating power and subcarrier to the users in Orthogonal Frequency Division Multiple Access (OFDMA) networks. Utility function is a proven approach for fair and efficient radio resource allocation. Most of the proposed schemes in the related literature consider continuous rate adaptation. However, our proposed algorithm utilizes...
This paper proposes a novel admission control (AC) algorithm for guaranteed quality of service (QoS) to all users. The proposed solution provides better utilization of system capacity using adaptive modulation (AM). A scheduler based on a per user priority function is also given in this paper. The AC is given by allocating the exact number of slots for each user that will meet its QoS. For every new...
The important problem of resource allocation in multi-user wireless networks is that to achieve the balance between efficience and fairness. In this paper, by using the cross-layer optimization mechanism, we derive an optimization model to obtain efficient and fair downlink sub-carrier allocation in multi-user OFDM wireless networks. A dynamic sub-carrier allocation algorithm (DSAA) is proposed in...
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