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Inter-cell interference coordination (ICIC) is one of the key technologies in the multi-cell radio resource management of mobile systems. It plays a vital role in mitigating strong inter cell interference and guaranteeing proper quality of services for in-progress sessions. Because heterogeneous deployment is adopted in LTE-Advanced, and interference problem becomes serious. In this paper, we propose...
We report on field trials using CoMP transmission in the downlink of a mobile radio network. Two new features enable over-the-air CoMP transmission from physically separated base stations and terminals. These are distributed synchronization and a fast virtual local area network. Using VLAN tags, terminals feed back the multi-cell channel state information to their serving bases where it is multiplexed...
Based on a survey on the technical challenges to the future radio access network beyond LTA-Advanced, which should offer very high average areal throughput to support a vast amount of data traffic and user density with energy-efficient operation, we discuss the potential techniques and propose an overall framework.
This paper studies the performance of a superposition based approach for multi-user access in the uplink of a wireless cell. The approach uses non-orthogonal signaling and multi-user detection on top of an orthogonal multiple-access method like OFDMA. Path losses depending on the distance between a terminal and the base station and cancellation errors during multi-user detection are taken into account...
Energy consumption of mobile access networks has recently received increased attention. Although cellular networks account for a rather small share of energy that is used by the ICT (Information and Communication Technology) sector, lowering their energy consumption appears important from an economical perspective. This paper recalls different means to enhance the capacity of evolved mobile networks...
The throughput of conventional wireless multicast systems is limited by the multicast user with the lowest channel quality, which leads to a very low throughput especially if the number of users is large. In this paper, we show that hybrid-automatic repeat request with Chase combining (HARQ-CC) is a promising technique to overcome this problem and optimize the transmission rate of wireless multicast...
Femtocells are being deployed for coverage extension and higher data rates. However, interference problem between macrocell and femtocells should be solved before massive deployment. In this paper, we analyze the possible cases of frequency resource allocation in the OFDMA femtocell systems using Fractional Frequency Reuse (FFR) in order to minimize the interference between both cells. Under the assumed...
Delay-based routing is proved to improve the network's round-trip time without enhancing its throughput. The reason is that optimising the end-to-end delay -as any load-based metric- creates route instability which results in packet reordering. This problem is detrimental for TCP. In the present work, we couple delay-based routing with a mechanism that locks, upon each node, the next-hop for each...
We have already proposed a hybrid single-carrier (SC) and multi-carrier (MC) system for next-generation mobile communication system. A SC signal has low peak-to-average power ratio (PAPR), which yields high power output for wide coverage. A MC signal is robust against frequency-selective fading and has high data rate with quadrature amplitude modulation (QAM). By appropriately selecting SC and MC...
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 order to overcome the indoor coverage problem for residential users, the deployment of home base stations (also referred as home-eNB) has been regarded as a promising solution. However, the unpredictable deployment pattern of home-eNBs makes centralized network planning impractical and requires distributed spectrum planning to achieve effective interference management. In this paper, by enabling...
In this paper we present a novel Hybrid Automatic Repeat reQuest (HARQ) scheme for cooperative communication systems, called Coded Partial Retransmission (CPR). The method is based on the retransmission of only a fraction of the original codeword by the cooperating nodes, applying an appropriate power allocation. Numerical results using LDPC codes and Type-I HARQ with Chase Combining show that CPR...
It has been recognized that a primary method of further enhancing the spectral efficiency of LTE Release-8 is to improve support for multi-user (MU) MIMO transmission in the downlink in an efficient manner. This paper investigates the performance improvements due to the enhanced support of single-cell MU-MIMO within the framework of LTE evolution (specifically LTE Release-9 and Release-10 also known...
In this paper, we propose an interference aware throughput maximizing scheduler for cognitive radio networks (CRNs) as part of a MAC layer resource allocation framework. In the considered CRN scenario, the cognitive users with multiple antennas are coordinated by a centralized cognitive base station. We evaluate the performance of our proposed scheme using analysis of variation (ANOVA) technique....
A Hybrid ARQ (HARQ) scheme employing a flexible amplify and forward (AF) relaying is considered for a cooperative relay channel. Two phase types with flexible length: one phase for relay reception and another phase for relay forwarding are assumed to accommodate half duplex relaying. We assume two types of encoding: repetition coding (RC) and unconstrained coding (UC). The outage performance of the...
The use of relays is a promising way to extend coverage and increase rates in Long Term Evolution Advanced (LTE Advanced) networks. Performing a transmission in several hops (BS-relay & relay-user) requires more radio resources than a single hop transmission. This paper analyses how the available radio resource should be allocated between relays and users in order to maximize throughput and/or...
Current cellular systems suffer from co-channel interference, when simultaneous transmissions in other cells use the same physical resources. Schemes involving cooperation between Base Stations (BS) are currently discussed for further releases of the 3GPP Long Term Evolution (LTE) system as a promising method to mitigate co-channel interference for users located at cell-edge. The BS cooperation approach...
Distributed beamforming has the great potential of performance improvement in wireless networks while the carrier synchronization overhead will reduce its performance gain. In this paper the effects of carrier synchronization on link throughput of distributed beamforming is studied. The expressions of the frequency and initial phase used by each cooperative node are derived for the existing round-trip...
In this paper, a new joint scheduling and hybrid resource allocation method is derived and investigated for a multi-user downlink Orthogonal Frequency Division Multiple Access (OFDMA) system that provides Time Delay-Sensitive services (TDS) and Time Delay-Insensitive services (TDI). A three sectored multi-cellular heterogeneous traffic environment is considered where users are randomly distributed...
In the multi-cell environment, the approaches that are suitable for the single cell scenario may cause excessive interference to other cells and become suboptimal. In this paper, we present a number of receiver-centric power allocation schemes that take into account the detrimental impact of allocated resources to the neighboring cells, and use it as a guideline in determining the appropriate power...
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