Search for: multi-cell-networks
M.Sc. Thesis Sharif University of Technology ; Hossein Khalaj, Babak ; Behrouzi, Hamid
In recent years, base station coordination (also known as network MIMO) has been analyzed as a means of handling inter cell interference. In principle, all base stations might share their CSI and data through backhaul links. Unfortunately, the demands on backhaul capacity and computational power scale rapidly with the number of cells, which makes this approach unsuitable for practical systems. And these problems shift the researches to find ways for turning this idea to an idea that can be used in practical systems. One of the major changes to this idea can be dealing with local CSIT that there would be no need to exchanging CSIT among BSs. The other change that can make the idea to a more...
Article Wireless Communications and Mobile Computing ; Volume 2018 , 2018 ; 15308669 (ISSN) ; Akar, N ; Khalaj, B. H ; Sharif University of Technology
Hindawi Limited 2018
A semicentralized joint cell muting and user scheduling scheme for interference coordination in a multicell network is proposed under two different temporal fairness criteria. In the proposed scheme, at a decision instant, each base station (BS) in the multicell network employs a cell-level scheduler to nominate one user for each of its inner and outer sections and their available transmission rates to a network-level scheduler which then computes the potential overall transmission rate for each muting pattern. Subsequently, the network-level scheduler selects one pattern to unmute, out of all the available patterns. This decision is shared with all cell-level schedulers which then forward...
M.Sc. Thesis Sharif University of Technology ; Hossein Khalaj, Babak ; Behroozi, Hamid
Time offset (TO) at an orthogonal frequency division multiplexing (OFDM) system destroys orthogonality of subcarriers and causes interchannel interference (ICI) and inter symbol interference (ISI). This problem is more challenging in multi-user multi-input multi-output (MU-MIMO) OFDM systems such as coordinated multi-point (CoMP) uplink transmission where joint processing is performed at base stations (BSs) and different delays form users to BSs cannot be compensated by timing strategies. In this thesis, we use delay-amplify and forward relays and post processing at receivers to decrease signal to interference plus noise ratio (SINR) degradation due to large TOs at insufficient cyclic prefix...
M.Sc. Thesis Sharif University of Technology ; Hossein Khalaj, Babak
In recent years, introduction of new technologies has highlighted the need to more data rate in mobile networks. Classical methods of resource allocation in mobile networks cannot respond to this huge demand for data rate because of their limitations. Resource allocation, as one of the operators’ tasks, plays a key role in the network efficiency and users’ data rate. Opportunistic resource allocation and scheduling have gained attention in recent years. On the other, using single-channel (frequency reuse-1) networks is also one of the methods to improve data rate in mobile networks. It is expected that the use of opportunistic scheduling in single-channel networks can repond to the huge...
Article 2012 6th International Symposium on Telecommunications, IST 2012 ; 2012 , Pages 289-294 ; 9781467320733 (ISBN) ; Behroozi, H ; Khalaj, B. H ; Sharif University of Technology
In this paper, we study the power allocation problem in multi-cell orthogonal frequency division multiple access (OFDMA) networks. In order to improve system performance in cell-edges, users are separated into two groups with respect to their distance from base-stations (BSs): Central users and cell-edge users. Coordinated multi-point joint transmission (CoMP-JT) technology incorporated with static clustering is used for users near the cell-edges. In addition, our goal is to serve users with different target signal to interference plus noise ratio (SINR) according to their requested quality of services. Consequently, revenue of the service provider is considered as another factor and two...
Article Eurasip Journal on Wireless Communications and Networking ; Volume 2016, Issue 1 , 2016 ; 16871472 (ISSN) ; Oliaiee, A ; Behroozi, H ; Khalaj, B. H ; Sharif University of Technology
Springer International Publishing
In this paper, we study the power allocation problem in multi-cell OFDMA networks, where given the tradeoff between user satisfaction and profit of the service provider, maximizing the revenue of the service provider is also taken into account. Consequently, two Stackelberg games are proposed for allocating proper powers to central and cell-edge users. In our algorithm, assuming the fact that users agree to pay more for better QoS level, the service provider imposes optimum prices for unit-power transmitted to users as they request different levels of QoS. In addition, in order to improve system performance at cell-edge locations, users are divided into two groups based on their distance to...