On the Efficiency Improving Technologies of Next Generation Wireless Networks
Date Issued
2010
Date
2010
Author(s)
Hong, Wei-Chih
Abstract
In the evolution of wireless network technologies, the pursuit of higher efficiency and larger capacity never stops. The next generation of wireless networks aims at achieving these goals via those techniques which can make use of the spectrum with more flexibility and higher order of diversity. These techniques include, to name a few, dynamic allocation of bandwidth/radio resources, aggregation of multiple channels/carriers, deployment of femto base stations, MIMO transmission with up to eight antennas, cooperative multipoint transmission, etc. In this dissertation, we focus on the first three techniques and present results for four research topics.
For the first topic, we present a model for the bandwidth/radio resource sharing in a wireless access network among multiple mobile virtual network operators (MVNOs). Within this model, we propose an efficient scheme to adaptively allocate the bandwidth in accordance with the traffic fluctuation. The proposed bandwidth allocation scheme adopts the technique of dynamic programming to maximize the expected total revenue across multiple stages from the perspective of the facility provider. The design is evaluated by simulation results and proved to be efficient and beneficial.
Concerning the second topic, we consider a scenario of aggregating multiple channels in order to serve as the wireless backhaul. Both the multi-hop nature and the large per packet channel access overhead of the wireless backhaul networks can lead to low channel efficiency. The problem may get even worse when there are many applications transmitting packets with small data payloads, e.g. Voice over Internet Protocol (VoIP). In order to cope with this issue, we propose a scheduler that concatenates small packets into large frames and sends them through multiple parallel channels with an intelligent channel selection algorithm between neighboring nodes. Besides the expected capacity improvement, delay bounds and call admission control principles of a broad range of scheduling algorithms for this scheduler have also been derived.
With respect to the third topic, we proposes a detailed model for the femtocell-based MVNO and analyzes the dynamics between the femto base station transmit power and its absorbing effect on the macrocell users via game theoretic techniques. The numerical results show that the power settings given by the Nash equilibrium maintain the required QoS level without causing excessive interferences. Such results should support the feasibility of large-scale deployment of femtocell-based MVNOs.
The last study of this dissertation is a mixture of the ideas of the three techniques. It proposes a set of low-complexity schemes to improve the spectral efficiency of the femtocells in LTE-Advanced by intelligently allocating multiple carriers. The introduction of carrier aggregation in LTE-Advanced provides the uncoordinatedly deployed femtocells with the opportunity to autonomously mitigate the interferences. In order to address the inefficiency of the autonomous component carrier selection (ACCS) scheme proposed by 3GPP in a typical home Internet access scenario, we propose a scheme to improve the total throughput of a cluster of femtocells by reselecting the carriers according to a well-planned order. Additionally, we also propose to ameliorate the performance of the cell edge users with the fractional power suppression technique. Both the proposed schemes are shown to improve the original ACCS without requiring extra measurements and with only limited additional signaling overhead.
Subjects
dynamic bandwidth allocation
MVNO
multichannel scheduler
packet concatenation
femtocell
carrier selection
Type
thesis
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