Toward seamless networking in indoor environments in millimeter wave bands

This thesis investigates the possibility of applying the 60GHz band to the indoor networking environment at the systemand link control levels. The work presented in this thesis aims at developing novel systemconcepts for seamless and cost-effective broadband local area networks operating in the 60GHz band in particular andmillimeter-wave bands in general. Different from many efforts today targeting point-to-point cable replacement solutions, this thesis attempts to apply the 60 GHz band to a broader context, i.e., the local area network environment in which multiple users and multiple applications share the network resource simultaneously. The utilization of this millimeter wave band, however, leads to smaller radio cell coverage due to propagation losses and line-of-sight requirements. Indoor networks operating at this band will comprise a large number of pico-cells corresponding to that many of antenna stations. As a result, the cost of many antenna stations has become a major contributor for the total cost of the networks infrastructure. To reduce the systems cost, it is therefore crucial that the complexity of an antenna station is simplified.Radio over fiber (RoF) techniques can be employed to achieve this goal. Particularly, this thesis is based on a RoF technique called Optical Frequency Multiplication (OFM) that is able to generate pure millimeter wave carriers remotely. Instead of placing all the signal processing functions in antenna stations, it is now possible to concentrate those complex functions in a single processing block, i.e., the central station (CS). since the propagation of 60 GHz signals is highly obstructed by objects, it is generally difficult to obtain good signal coverage in the indoor environment. In this thesis, we propose the novel Extended Cell concept that is able to overcome the problem of insufficient signal coverage. In this solution, a number of adjacent radio cells are grouped into an extended cell. Furthermore, all the antenna stations in an extended cell are set to operate in the same radio channel. By controlling the cells to be included into an extended cell, overlap areas between extended cells can be created in transitional areas in the floor to ensure seamless handovers of ongoing connections. To optimize the performance of the system with regards to variable realtime traffic patterns, we propose an algorithm to dynamically form extended cells based on the actual traffic under each cell. The performance of twoMediumAccess Control protocols, i.e., IEEE 802.11 representing the distributed protocol family and IEEE 802.16 representing the centralized protocol one, when applied to the proposed RoF and extended cell based architecture is also discussed in this thesis. A major effect when an optical distribution system is inserted in a traditional wireless network is the additional propagation delay introduced by the fiber links. This additional propagation delay can exceed the timing boundary of the MAC protocols and eventually stop them from working. Another problem also arises when the utilization of the 60 GHz band is combined with the extended cell concept. Specifically, mobile stations in a room will be completely hidden to other stations in other rooms.We show that the throughput of both protocols degrades when the length of optical distribution network increases, but this degradation is not significant.With regards to the hidden terminal problem, the performance of distributed and carried sense based protocols is severely affected. Finally, this thesis concerns the issues of maintaining quality of services (QoS) when the MAC protocols are applied to the proposed network architecture. We have shown that the proposed architecture does not affect the service differentiation mechanisms of the MAC protocols. Moreover, in this architecture, since the central station has the full control of the network, QoS and mobility control algorithms can also be greatly simplified to improve the performance of the network