224 research outputs found

    Nearly Optimal Resource Allocation for Downlink OFDMA in 2-D Cellular Networks

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    In this paper, we propose a resource allocation algorithm for the downlink of sectorized two-dimensional (2-D) OFDMA cellular networks assuming statistical Channel State Information (CSI) and fractional frequency reuse. The proposed algorithm can be implemented in a distributed fashion without the need to any central controlling units. Its performance is analyzed assuming fast fading Rayleigh channels and Gaussian distributed multicell interference. We show that the transmit power of this simple algorithm tends, as the number of users grows to infinity, to the same limit as the minimal power required to satisfy all users' rate requirements i.e., the proposed resource allocation algorithm is asymptotically optimal. As a byproduct of this asymptotic analysis, we characterize a relevant value of the reuse factor that only depends on an average state of the network.Comment: submitted to IEEE Transactions on Wireless Communication

    Interference management for co-channel mobile femtocells technology in LTE networks

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    The dense deployment of Femtocells within the Macrocell's coverage is expected to dominate the future of Long Term Evolution (LTE) networks. While Mobile Femtocells (Mobile-Femtos) could be the solution for vehicular networks when there is a need to improve the vehicular User Equipment (UE) performance by mitigating the impact of penetration loss and path-loss issues. The deployed Femtocells have operated in a co-channel deployment due to the scarcity of spectrums. This issue causes interference between Femtocells and Macrocells as well it causes extra overhead on the LTE networks because of the co-tire interference between adjacent Femtocells. In this paper two interference scenarios are considered, the interference between Mobile-Femto and Macrocell, and the interference between the Mobile Femtos themselves. Therefore, to avoid the generated interference between Femtocells, the controlled transmission powers as well as the coverage planning techniques have been discussed. While in the worst-case scenarios, a frequency reuse scheme has been proposed to avoid the generated interference effectively and dynamically between the Mobile-Femtos as well as their UEs and between the Macrocell UEs

    Interference management for co-channel mobile femtocells technology in LTE networks

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    The dense deployment of Femtocells within the Macrocell's coverage is expected to dominate the future of Long Term Evolution (LTE) networks. While Mobile Femtocells (Mobile-Femtos) could be the solution for vehicular networks when there is a need to improve the vehicular User Equipment (UE) performance by mitigating the impact of penetration loss and path-loss issues. The deployed Femtocells have operated in a co-channel deployment due to the scarcity of spectrums. This issue causes interference between Femtocells and Macrocells as well it causes extra overhead on the LTE networks because of the co-tire interference between adjacent Femtocells. In this paper two interference scenarios are considered, the interference between Mobile-Femto and Macrocell, and the interference between the Mobile Femtos themselves. Therefore, to avoid the generated interference between Femtocells, the controlled transmission powers as well as the coverage planning techniques have been discussed. While in the worst-case scenarios, a frequency reuse scheme has been proposed to avoid the generated interference effectively and dynamically between the Mobile-Femtos as well as their UEs and between the Macrocell UEs

    A Framework for Uplink Intercell Interference Modeling with Channel-Based Scheduling

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    This paper presents a novel framework for modeling the uplink intercell interference (ICI) in a multiuser cellular network. The proposed framework assists in quantifying the impact of various fading channel models and state-of-the-art scheduling schemes on the uplink ICI. Firstly, we derive a semianalytical expression for the distribution of the location of the scheduled user in a given cell considering a wide range of scheduling schemes. Based on this, we derive the distribution and moment generating function (MGF) of the uplink ICI considering a single interfering cell. Consequently, we determine the MGF of the cumulative ICI observed from all interfering cells and derive explicit MGF expressions for three typical fading models. Finally, we utilize the obtained expressions to evaluate important network performance metrics such as the outage probability, ergodic capacity, and average fairness numerically. Monte-Carlo simulation results are provided to demonstrate the efficacy of the derived analytical expressions.Comment: IEEE Transactions on Wireless Communications, 2013. arXiv admin note: substantial text overlap with arXiv:1206.229

    Uplink Resource Allocation in Relay Enhanced LTE-Advanced Cellular Networks

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    In parallel to HSPA evolution, 3GPP has adopted the Long Term Evolution track to fulfill the performance targets of 4G cellular networks. Multi-hop networks consisting of fixed decode and forward relays nodes are proposed to relax the capacity and coverage limitations encountered by traditional macro base station deployments. The relays are designed to operate on the in-band spectrum and support self-backhauling of user data. This thesis work provides an insight into the impact of uplink resource allocation in delivering improved user experience in relay enhanced cellular networks. Radio resource allocation and power control play a crucial role in the performance of wireless communication systems. System level simulations reveal that reuse 1 based relay enhanced cells operate in an interference limited scenario. Therefore, a resource allocation scheme based on user grouping is investigated to coordinate and mitigate the negative effect of interference. It is shown that the proposed methodology is spectrally efficient and delivers improved system performance. In addition to improving system performance, relaying is seen to be beneficial in significantly reducing battery consumption in devices. This is highly appealing since the next generation cellular networks are targeted towards higher bit rates and extended periods of mobile data usage. This work provides specific insights into the performance limiting criteria of the envisaged multi-hop system and, furthermore, is expected to contribute towards 3GPP's standardization of the relaying study item
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