Broadband and Mobile Network

As we move towards a communication paradigm involving human-human, human-machine, machine-machine interactions, it is clear that no single networking technology – wired or wireless - will fit all the requirements of every platform and user. We will need multiple ways to connect in order to achieve the optimum combination of bandwidth, reliability, and cost for different usage scenarios and applications for short-range, local, and wide areas. A fundamental challenge is to provide users with seamless mobility across heterogeneous wireless networks without requiring them to be involved with cumbersome technical issues. A high-capacity optical backbone network must support and interconnect these diverse access systems.

The information network of the future will be characterized by its very large scale, the amount of traffic carried and the quality of service it provides. These scaling factors put heavy emphasis on implementing efficient networks. The optical backbone must incorporate transparent optical nodes, a fast control plane, efficient multiplexing and routing of different traffic types, and cost-effective add/drop of broadband access traffic. Wireless technologies with higher bandwidth and reach such as WiMax allow for a seamless extension of broadband access from this optical backbone to the end user. Underutilized bandwidth in broadband networks needs to be recovered to improve network efficiency.The optical backbone must incorporate transparent optical nodes, a fast control plane, efficient multiplexing and routing of different traffic types, and cost-effective add/drop of broadband access traffic.

The edge node in optical networks is the focus of efforts to enhance the capacity and quality of service performance of the metropolitan optical backbone.  It must interface wired broadband access systems, such as PON (passive optical network), and wireless access systems such as WiMax and cellular mobile.  An edge node architecture that provides interfaces in an efficient modular way, multiplexes traffic into WDM (wavelength division multiplexed) and subcarrier channels, provides fast switching capability, and carries quality of service across network boundaries is essential.

For wireless networks, congested cells are a major problem in cellular networks with their ever-increasing data traffic. Furthermore, the downlink data rate to a mobile user can significantly degrade because of the channel condition or poor coverage. Deploying more base stations and decreasing the cell size may not be a cost effective option to alleviate the problem; neither is using wireless relay stations operating on the same 3G spectrum, since it can lead to interference with other cells.

The efficiency of a wireless network is only as good as the efficiency of its underlying layers. The comprehensive efficient design, architecture and performance should not only cover all the layers, from physical to network to service, but their interaction as well. In addition to the single-hop model for today's cellular/wireless networks, another model based on radio-to-radio multi-hopping has emerged: ad-hoc, self-organized networks that can be dynamically configured. These rapidly deployable networks are useful for applications such as information sharing, emergency relief efforts during disasters, sensor networks, or as an alternative to traditional networking in developing areas without an existing communication infrastructure. They can also serve as a complement to a regular infrastructure for cost or other reasons.

These networking paradigms pose many technical issues that result from traffic loading variations, changing/unpredictable network topology changes, high degree of mobility, intermittent connection, bandwidth limitations. Security, routing, and mobility management represent major research challenges.

NEC Labs America pursues the following research themes in Broadband and Mobile Networks: High-performance metropolitan optical networks and devices, mobility management, overlay networks, self-organizing, ad-hoc wireless networks, grid networking, optical/wireless integration.

Mobile Communications and Networking