Future 4G systems: The multisphere concept

In an attempt to describe a user-centric wireless world, the WWRF(Wireless World Research Forum) advocates the use of a multisphere model where each sphere can be seen as a particular level of interaction in the communication realm. The illustration below illustrates the multisphere concept for future wireless communications systems.

The inner most position in this model is occupied by the user. The surroundings closest to the user, stretching only within the reach of his or her arms and including also the user’s actual body and wearable elements, define the operational environment of a personal area network (PAN), indicated by (1) in the illustration above. The user could wear, carry, and hold a number of devices that can communicate not only with each other but also with devices in other spheres of the model. The immediate environment (2) is formed by the familiar elements (e.g., devices with communication capabilities) located at a close distance to the user, typically within the user’s room. These elements, home appliances, office tools, and so forth, would be simply, cleverly, and intuitively connected to the user-that is, in an invisible, always-present fashion. Instant partners (3) represent ad hoc associations with other people or complex entities (e.g., vehicles) for interacting, exchanging information, and socialization purposes. In principle, any communication taking place within or between the three first spheres can be classified as short range, owing to the fact that the maximum distances involved are on the order of 1m (1), 10m (2) and 100m (3). A number of key techniques are being studied in WWRF in order to provide short-range connectivity, based on radio (e.g., multicarrier systems, UWB) or based on optical wireless communications. The next level in the model covers a wide area and it corresponds then to the radio access (4) sphere. At this level full coverage is provided, including connectivity of remote users and connectivity of the lower spheres. WWRF foresees that in addition to conventional radio access technologies (e.g., base stations, satellites) a number of new access techniques will be incorporated. These include base stations in high altitude platforms (HAPS), high-speed local media points for digital broadcasting systems, and other special air interfaces. Based on the above model and definition, one can expect that the number of entities with the potential to be connected (individuals and machines) is virtually beyond measure. The next sphere models the provision of seamless wireless interconnectivity (5). Given the high degree of heterogeneity of terminals, air interfaces, and networks, it is likely that adaptive and reconfigurable solutions as well as radio convergence layers will be used to ensure ubiquitous and seamless operation. To this end, at the highest level of abstraction, WWRF includes the cyber world in the model (6). This extension of the real world allows users to interact in an artificially created environment, which it manifests as realistic and appealing. Ubiquitous wireless access to the cyber world completes the overall scene envisaged for future communications systems.

WWRF has also identified a number of fundamental building blocks for future wireless communication systems. These are: (1) 4G radio interfaces, (2) cooperative networks and terminals, (3) smart antennas and base stations, (4) software defined radio, (5) semantics aware services, (6) end-to-end security and privacy, (7) heterogeneous ad hoc networking, and (8) peer discovery. The work in different WPs and SIGs is basically organized around targets defined by the sphere model and these building blocks.

WWRF is now the largest global initiative focused on future 4G systems. There are many possible reasons why the WWRF is enjoying high interest in the current world of wireless technology and why there was a need for this kind of initiative in terms of developing the Forum.

1. Some areas of the wireless industry were showing promising signs (WLAN coming into the home and office), indicating that a newer, different way of working with wireless technology might be emerging, one that would benefit from research investment in the area.

2. Spectrum allocation was, and still is, a lengthy process, and despite the slowdown in the mobile industry, some measures are still needed to ensure the industry does not stagnate altogether.

3. Through technical collaboration and through a united framework, better research results might be expected for future 4G mobile communications. Investment risks can be kept to a minimum in such a shared approach since collaboration reduces research costs, a fact that is greatly appreciated in times where there is an apparent recession in the mobile communication sector.

The above reasons give some clues as to why the WWRF is experiencing a high interest rate.