The hybrid wireless-optical broadband-access network (WOBAN) is a promising architecture for future access
networks. Recently, the wireless part of WOBAN has been gaining increasing attention, and early versions are being
deployed as municipal access solutions to eliminate the wired drop to every wireless router at customer premises.
This architecture saves on network deployment cost because the fiber need not penetrate each end-user, and it
extends the reach of emerging optical-access solutions, such as passive optical networks. This paper first presents
an architecture and a vision for the WOBAN and articulates why the combination of wireless and optical presents a
compelling solution that optimizes the best of both worlds. While this discussion briefly touches upon the business
drivers, the main arguments are based on technical and deployment considerations. Consequently, the rest of this
paper reviews a variety of relevant research challenges, namely, network setup, network connectivity, and
fault-tolerant behavior of the WOBAN. In the network setup, we review the design of a WOBAN where the back end is a
wired optical network, the front end is managed by a wireless connectivity, and, in between, the tail ends of the
optical part [known as optical network unit (ONU)] communicate directly with wireless base stations (known as
“gateway routers”). We outline algorithms to optimize the placement of ONUs in a WOBAN and report on a
survey that we conducted on the distribution and types of wireless routers in the Wildhorse residential neighborhood
of North Davis, CA. Then, we examine the WOBAN's routing properties (network connectivity), discuss the pros and
cons of various routing algorithms, and summarize the idea behind fault-tolerant design of such hybrid networks.
© 2007 IEEE
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