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In this paper, we propose a resource-efficient cooperative multiple-input single-output (MISO) technique to reliably deliver multicast IPTV content in WiMAX networks. To support the strict quality of service requirements of the IPTV service within a cooperative framework, we utilize a two-phase based transmission strategy, which allows the session users to reliably receive the multicast data either...
We study the mobile association problem: we determine the cells corresponding to each base station, i.e, the locations at which intelligent mobile terminals prefer to connect to a given base station rather than to others. This paper proposes a new approach based on optimal transport theory to characterize the solution based on previous works on fluid approximations. We characterize the optimal solution...
Cognitive radio in network core devices such as basestations is being considered as a spectrum management solution for future society's communication demands. Aside from new resource allocation algorithms, efficient inter- and intra-protocol processing should be considered. We propose an opportunistic cross layer architecture called COmmon Layer Architecture (COLA) for information exchange between...
Fractional frequency reuse (FFR) is an interference coordination technique well-suited to OFDMA based wireless networks wherein cells are partitioned into spatial regions with different frequency reuse factors. This work focuses on evaluating the two main types of FFR deployments: Strict FFR and Soft Frequency Reuse (SFR). Relevant metrics are discussed, including outage probability, network throughput,...
This paper considers the control signaling on the downlink in wireless multiple access systems, with focus on the part of the control signaling that carries information on the user's time/frequency scheduling assignments. A new idea is presented to reduce the amount of channel resources needed for this signaling. The idea is to exploit the fact that provided that only one single user is scheduled...
In Cognitive Radio (CR) networks, the licensed but vacant spectrum bands are assigned to the CR users in an opportunistic manner. These assignments should be realized according to the activities of the licensed users in the spectrum as well as the throughput requirements of the CR users. Considering these two main challenges, in this paper, we investigate the spectrum assignment problem in centralized...
This paper investigates the uplink throughput of network MIMO cellular systems at low signal-to-noise ratio (SNR). The network is modeled according to Wyner's extended cellular model, with intracell orthogonal medium access control. We derive analytical expressions for the two key low SNR parameters; namely, the minimum required Eb/N0 for reliable communications and the wideband slope, assuming noncooperative...
Long Term Evolution (LTE), the next-generation network beyond 3G, is designed to support the explosion in demand for bandwidth-hungry multimedia services that are already experienced in wired networks. To support Multimedia Broadcast/Multicast Services (MBMS), LTE offers functionality to transmit MBMS over a Single Frequency Network (MBSFN), where a time-synchronized common waveform is transmitted...
Inter-cell interference management is one of the most important issues in next generation wireless networks. As opportunistic beamforming induces more fluctuations in the channel, it can be used as an effective means for inter-cell interference management. In this paper, we present a new scheme to decrease inter-cell interference by utilizing the information of user locations along with the inter-base...
Coordinated multipoint (CoMP) transmission is being considered in next-generation cellular systems to improve cell-edge throughput. In this paper, we consider open-loop CoMP with L base stations (BSs) where they cooperatively serve a cell-edge user. We first propose antenna selected space-time block code (STBC) to exploit diversity gain for serving the cell-edge user and also support the scenario...
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...
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...
In current wireless standards like 3GPP LTE or IEEE 802.16 / WiMAX multiple access is based on orthogonal signalling using single-carrier frequency-division multiple access (SC-FDMA) or orthogonal frequency-division multiple access (OFDMA). Links between a base station and different terminals use mutually orthogonal radio resources. This paper studies potential gains in average cell throughput by...
In wireless cellular networks, indoor coverage is a problem from the perspective of the service provider. A femto Access Point, also known as femto AP, is utilized to solve the problem. Generally, the femto AP is deployed in a home to support indoor users. Since there might be a small number of users in the home, it could be expected that the traffic load of the femto AP is lower than its wireless...
This paper investigates and proposes the techniques that reduce the number of required feedback channels for implementation of opportunistic scheduling. It is shown that by implementing effective schemes we can exploit significant multiuser diversity gain using a modest number of feedback channels. Simulation based performance analysis is given to demonstrate effectiveness of the proposed schemes...
In cognitive radio networks, both the sensing time and the fusion schemes used for cooperative spectrum sensing affect the detection probabilities of the primary users and the throughput of the secondary users. Therefore, joint optimization of the sensing time and the cooperative fusion scheme has been studied before in terms of sensing-throughput tradeoff design. In this paper, different from the...
A two-user uplink interference channel with hybrid automatic retransmission request (HARQ) and base station cooperation is analyzed. Two forms of base station cooperation are studied: wireless and wireline cooperation. In wireless cooperation, the first base station that decodes its desired user's message acts as a relay for the co-channel user via space-time coding during the remaining HARQ rounds...
Energy efficiency in information and communications technology, and in cellular mobile radio networks in particular, is gaining in importance not only with regard to the ecological assessment. Reducing the power consumption of mobile radio systems has recently attracted attention of network operators as energy costs make up a vast portion of today's operational expenditure. In this regard, it is often...
This paper studies the different ways of extending wireless coverage for high data rates and improving the data capacity in a building. The solutions considered include deployments of single or multiple small base stations, i.e. Picocell or Femtocell, and distributed antenna system, operated on the same frequency as the macro cellular network. We look at the radio performance of each solution in a...
Optimization of the energy efficiency is considered not only to positively contribute to the ecological assessment, but gains in importance from operator's point of view as well, since energy costs for running a mobile radio network have an increasing share of the operational expenditure. From this perspective, the utilization of small, low power base stations is regarded as a promising strategy to...
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