Faced with the ever-increasing trend of the cellular network scale, how to quantitatively evaluate the effectiveness of the large-scale deployment of base stations (BSs) has become a challenging topic. To this end, a deeper understanding of the cellular network topology is of fundamental significance to be achieved. In this paper, @math -Shape, a powerful algebraic geometric tool, is integrated into the analysis of real BS location data for six Asian countries and six European countries, respectively. Firstly, the BS spatial deployments of both Asian and European countries express fractal features based on two different testifying metrics, namely the Betti numbers and the Hurst coefficients. Secondly, it is found out that the log-normal distribution presents the best match to the cellular network topology when the practical BS deployment is characterized by the Euler characteristics.
Understanding the network topology can prominently facilitate the design of efficient cellular networks, and pervasive applications depending upon the network topology have been found in the wireless communication field. For instance, the knowledge of network topology can be exploited to perform automatic computations for topology control in WSNs @cite_6 , investigate the pros and cons of BS switching on off scheme @cite_8 , develop energy-saving mechanism for green cellular networks @cite_25 , improve the spectral efficiency and reduce the bit error rate (BER) in space-time network coding (STNC) scheme @cite_40 , manage the interference and allocate spectrum resource for a femtocell-based cellular network @cite_20 and so on.
@cite_8 @cite_6 @cite_40 @cite_25 @cite_20
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While the deployment of base stations (BSs) becomes increasingly dense in order to accommodate the growth in traffic demand, these BSs may be under-utilized during most hours except peak hours. The deactivation of these under-utilized BSs is regarded as the key to reducing network power consumption; however, the remaining active BSs should increase their transmit power in order to fill network coverage holes that result from BS switching off. This paper investigates the optimal balance between such beneficial and harmful effects of BS switching off in terms of minimizing the network power consumption, through comprehensively considering the spatial BS distribution, BS transmit power, BS power consumption behaviors, radio propagation environments, and frequency reuse. The suboptimal and approximated design problems are formulated as geometric programming and the numerical results demonstrate that the proposed suboptimal solutions for the spatial density, transmit power, and frequency reuse of remaining active BSs significantly contribute to reducing the power consumption of BSs. We use cellular automata for simulating topology control algorithms in Wireless Sensor Networks (WSNs). A cellular automaton is a decentralized computing model providing an excellent platform for performing complex computations using only local information. WSNs are composed of a large number of distributed sensor nodes operating on batteries; the objective of the topology control problem in WSNs is to select an appropriate subset of nodes able to monitor a region at a minimum energy consumption cost thus extending the network lifetime. We have used cellular automata to model a randomized WSN topology control algorithm and have experimentally evaluated its performance. Space-time network coding (STNC) is a time-division multiple access (TDMA)-based scheme that combines network coding and space-time coding by allowing relay nodes to combine the information received from different source nodes during the transmission phase and to forward the combined signal to a destination node in the relaying phase. However, STNC schemes require all the relay nodes to overhear the signals transmitted from all the source nodes in the network. They also require a large number of time-slots to achieve full diversity in a multipoint-to-multipoint transmission. Both conditions are particularly challenging for large cellular networks where, assuming a downlink transmission, base stations (BSs) and users only overhear a subset of all the BSs. In this paper, we exploit basic knowledge of the network topology in order to reduce the number of time-slots by allowing simultaneous transmissions from those BSs that do not overhear each other. Our results show that these topology-aware schemes are able to increase the spectral efficiency per time-slot and bit error rate with unequal transmit power and channel conditions. Reducing the energy consumption (EC) of base station (BS) is one of the major concerns in wireless cellular networks. Additionally, turning off some underutilized BSs during off-peak period and performing effective compensation without delay are the most efficient way to save energy. However, large-scale energy conservation yet remains to be investigated at macro level. In this paper, to solve the problem that long convergence time and poor convergence precision in the large-scale network, we propose a BS topology-aware based energy-saving (ES) model, whose core is cell adjacency graph (CAG) with vertexes and links representing eNodeBs (eNBs) and their neighboring relationship. In addition, we introduce new metrics, predicted energy efficiency (PEE) and quality of compensation (QoC), as the weights of nodes and links respectively. Consequently, the model transforms the ES problem into average weights maximization in CAG. In view of the model presented, centralized and hybrid algorithms are put forward to solve the problem. Compared with classic distributed algorithm, simulation results claim that our hybrid approach achieves the maximization of ES with guaranteed QoC while our centralized approach maximize the PEE. Femtocell (FC) is a low-power, low cost indoor cellular base station (BS) installed by an end user at home or in an office environment. A typical indoor coverage of an FC is tens of meters and could cover several rooms. When Femto base stations (F-BS) are densely deployed, interference between them becomes an unavoidable issue. Hence, there is an immediate need for a robust interference management technique before femtocells can be extensively adopted for commercial purpose. In this paper, we propose a distributed algorithm that takes into account dynamic topology of FCs and carefully allocates communication channels to each F-BS. This also addresses the co-domain interference problem in FCs. We perform extensive simulations to demonstrate the novelty of our proposed scheme, called as distributed topology-based spectrum allocation. This avoids spectrum overlap that facilitates efficient resource allocation for each cell, thereby enabling low interference under high resource utilization and increased reuse efficiency.