Challenges for Future 4G Networks

We have established that 4G convergence is expected to deal with several environments, including short range networks, which, in general, involve devices with capabilities subject to CPU, memory and disk limitations. Thus, with regard to routing, the next generation network should consider strategies that conserve battery power not only from a device survival point of view but more importantly in an attempt to use greener environment friendly solutions. These are also known as power-aware routing. For example, these devices should avoid the use of highly demanding table updates.

Routing mechanisms using location information have been proposed in order to improve energy consumption and data delivery. Note that the excessive use of location information from devices such as GPS for routing decisions can lead to a considerable increase in energy consumption when compared to location agnostic solutions. Moreover, vehicular networks are also expected to maintain location servers for vehicles to help in information routing.

In existing 2G and 3G networks, there is the horizontal cell connectivity handoff, one that involves cell changes by a terminal within the same type of network. 4G introduces also the vertical handoff. Here devices are expected to change networks they attach to. Hence, the challenge is to design routing protocols that are capable of handling vertical handoffs between pairs of different types of networks, while maintaining QoS requirements and optimizing common radio resources availability.

Under 4G networks, security is also seen as a paramount concern. Traditional attacks on existing IP networks will certainly migrate to 4G networks encouraged by both the heterogeneity and the open air interfaces of such networks. Routing information may be targeted in such attacks on system security, there is a need to design secure routing approaches to ensure the integrity of routing in 4G systems. This is not however the object of this chapter.

In summary, among the many routing-related challenges this work has identified, we mentioned QoS, security, energy and location information. The following section will present the details of new routing algorithms, with new network metrics and routing mechanisms, which motivate the extension of traditional classification to include epidemic, biological and social class of routing ideas, one expects to see in 4G networks.

WHY DO WE NEED NEW ROUTING MECHANISMS?

If anything is certain, the fact that 4G system will be completely IP-based is one. Although homogeneous at the higher levels of the architecture. 4G most likely will integrate several nestled networks with heterogeneous offered services, features, applications and service providers represented by mobile operators, companies or even individual users and content providers. The role of 4G systems in the wireless arena will be parallel to that of the Internet for fixed networks. It will be a common place to find the same service being offered by different sub-networks though maybe under varying security, bandwidth, delay, availability and pricing features.

While the prices for multi-radio and multi-interface devices are continuing to drop, new network topologies are also emerging including ad-hoc, mesh, hybrid and multi-dimensional ones. The latter are networks where a node may take part into different technology dependent networks at the same time, leading hence to a multi-layer view of the new topology. For this reason, new routing algorithms are designed to lead with new topologies and network challenges.

New Network Topologies

One expects that existing traditional network topologies such as those based on fixed infrastructure, ad hoc networks and others, to blend into 4G networks in a highly dynamic cooperating environment. 4G is also embracing highly dynamic networks such as delay tolerant or disruptive networks in addition to opportunistic communications which may be exploited in disaster recovery scenarios and military applications. The emergence of vehicular networks also presents new challenges to the design of 4G edge capacity and mobility support. VANs are expected to have bit rates close to those of fixed networks. New VAN topologies depict dynamic multi-hop short range vehicle-to-vehicle and vehicle-with-infrastructure communications.

Similarly to fixed networks, overlay topologies can run over 4G to offer virtual high level structures among individuals across 4G networks. Examples of such overlays are emerging new social networks, where topology information is primordial to improving data forwarding, privacy and security as seen in (Bernardos, Casar & Tarrio, 2006). Unlike current networks, a 4G one should open up further possibilities for individuals and groups to work, discuss and play together often by self-structuring driven by common interests, needs and incentives, instead of mere connectivity. The success of future 4G systems may depend to a great extent on their capacity to accommodate these new data services using social, biological and other nature inspired.