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OFDMA (Orthogonal Frequency-Division Multiple Access) is one of the most important technologies applied in Long Term Evolution (LTE) of wireless radio system [1]. In OFDMA system, dynamic resource block (RB) allocation is utilized as the effective way to achieve multi-user diversity gain, and also the factor which will greatly affect the QoS (Quality of Service) performance of each UE (User Equipment)...
Due to the propagation of smart handhold terminals, e.g. iPhone and iPad, the data traffic is growing rapidly in cellular networks. To fulfill the increased data traffic and attract more customers, the operators need to construct the network infrastructure and update their service planning, e.g. via introduction of flat-rate (FR) service plan. While along with the increase of data users, especially...
Carrier Aggregation (CA) is one of the important technologies to further improve the capacity of Long Term Evolution Advanced (LTE-A). When CA is conducted, a User Equipment (UE) will firstly select a Primary Serving Cell (PCell) for mobility support and then add Secondary Serving Cells (SCell) for higher experienced data rate. When and how to add/remove SCell is a very important issue, especially...
This paper focuses on investigating appropriate management of Component Carriers(CCs) in carrier aggregation( CA) system, which is identified as one of the most distinct features of 4G systems including Long Term Evolution- Advanced (LTE-A). An LTE-A user equipment (UE) is allowed to concurrently utilize multiple carriers, which leads to scalable increase in user throughput. However, in certain circumstances,...
The spread of mobile connectivity is generating major social and economic benefits around the world, while along with the rapid growth of new telecommunication technologies like mobile broadband communication and M2M (Machine-to-Machine) networks, larger number of various base stations will be employed into the network, which will greatly increase the power expense and CO2 emission. In order to degrade...
Quality of Experience (QoE) reflects the customer's perception of service, and is extremely important for operators. In VoIP service, variety of factors will affect customer's QoE, e.g. source data quality and the transmission channel condition. In cellular systems, although higher level of source coding will improve QoE, more radio resource will be consumed and thus degradation of system capacity...
This paper investigates flexible spectrum usages for LTE network that consists of overlaying macrocell and femtocell. In such a networking environment, shared spectrum usage and partitioned spectrum usage are two options to be employed between two radio tiers. After recognizing the pros and cons of these two usages, we propose hybrid spectrum usage to take advantage of their merits. In our proposal,...
This paper investigates flexible spectrum sharing for coexistence of macrocell and femtocell. In such a networking environment, shared spectrum usage and partitioned spectrum usage are two options to be employed between them. After recognizing the pros and cons of these two usages, we propose hybrid spectrum sharing to take advantage of their merits. In our proposal, the femtocells embedded in macrocell...
This paper investigates spectrum resource coordination for the mixed macrocell and femtocell deployment. Though sharing spectrum provides larger bandwidth for both macrocell and femtocell, cross-tier interferences exist and become drawbacks for them to achieve higher capacities. After analyzing the interferences when using shared spectrum, we propose to employ hybrid spectrum sharing with respect...
Wireless sensor networks (WSN) are a kind of networks made up of thousands of tiny nodes. The node in WSN has its own processor, memory, sensor and short-range wireless communication module. Due to the huge number of nodes, the cost of each node is restricted, which causes the limitation of the node's computing, caching and communicating ability. Because of these differences from normal lineal networks,...
Wireless sensor networks (WSN) are planted for sensing the area which people mostly concern and to send data of light, pressure, sound, and so on, back to people to make further analyses. Differ from normal lineal networks, WSN are usually restricted by energy store, plethoric information flow, and short communication distance. So, there are many research hotpots in WSN such as routing, economization...
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