1,038 research outputs found
Analysis of Static Cellular Cooperation between Mutually Nearest Neighboring Nodes
Cooperation in cellular networks is a promising scheme to improve system
performance. Existing works consider that a user dynamically chooses the
stations that cooperate for his/her service, but such assumption often has
practical limitations. Instead, cooperation groups can be predefined and
static, with nodes linked by fixed infrastructure. To analyze such a potential
network, we propose a grouping method based on node proximity. With the
Mutually Nearest Neighbour Relation, we allow the formation of singles and
pairs of nodes. Given an initial topology for the stations, two new point
processes are defined, one for the singles and one for the pairs. We derive
structural characteristics for these processes and analyse the resulting
interference fields. When the node positions follow a Poisson Point Process
(PPP) the processes of singles and pairs are not Poisson. However, the
performance of the original model can be approximated by the superposition of
two PPPs. This allows the derivation of exact expressions for the coverage
probability. Numerical evaluation shows coverage gains from different signal
cooperation that can reach up to 15% compared to the standard noncooperative
coverage. The analysis is general and can be applied to any type of cooperation
in pairs of transmitting nodes.Comment: 17 pages, double column, Appendices A-D, 9 Figures, 18 total
subfigures. arXiv admin note: text overlap with arXiv:1604.0464
Wireless Node Cooperation with Resource Availability Constraints
Base station cooperation is a promising scheme to improve network performance
for next generation cellular networks. Up to this point research has focused on
station grouping criteria based solely on geographic proximity. However, for
the cooperation to be meaningful, each station participating in a group should
have sufficient available resources to share with others. In this work we
consider an alternative grouping criterion based on a distance that considers
both geographic proximity and available resources of the stations. When the
network is modelled by a Poisson Point Process, we derive analytical formulas
on the proportion of cooperative pairs or single stations, and the expected sum
interference from each of the groups. The results illustrate that cooperation
gains strongly depend on the distribution of available resources over the
network.Comment: submitted, 12 pages, double-column, 7 figures, 8 sub-figures in tota
Discrete and Continuous Optimization Methods for Self-Organization in Small Cell Networks - Models and Algorithms
Self-organization is discussed in terms of distributed computational methods and algorithms for resource allocation in cellular networks. In order to develop algorithms for different self-organization problems pertinent to small cell networks (SCN), a number of concepts from discrete and continuous optimization theory are employed. Self-organized resource allocation problems such as physical cell identifier (PCI) assignment and primary component carrier selection are formulated as discrete optimization problems. Distributed graph coloring and constraint satisfaction algorithms are used to solve these problems. The PCI assignment is also discussed for multi-operator heterogeneous networks. Furthermore, different variants of simulated annealing are proposed for solving a graph coloring formulation of the orthogonal resource allocation problem.
In the continuous optimization domain, a network utility maximization approach is considered for solving different resource allocation problems. Network synchronization is addressed using greedy and gradient search algorithms. Primal and dual decomposition are discussed for transmit power and scheduling weight optimizations, under a network-wide power constraint. Joint optimization over transmit powers and multi-user scheduling weights is considered in a multi-carrier SCN, for both maximum rate and proportional-fair rate utilities. This formulation is extended for multiple-input multiple-output (MIMO) SCNs, where apart from transmit powers and multi-user scheduling weights, the transmit precoders are also optimized, for a generic alpha-fair utility function. Optimization of network resources over multiple degrees of freedom is particularly effective in reducing mutual interference, leading to significant gains in network utility. Finally, an alternate formulation of transmit power allocation is considered, in which the network transmit power is minimized subject to the data rate constraints of users. Thus, network resource allocation algorithms inspired by optimization theory constitute an effective approach for self-organization in contemporary as well as future cellular networks
セルラ分散MU-MIMO通信システムの干渉制御
Tohoku University博士(工学)thesi
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