Razstavljavci

The exchange of information using lightwave has a long standing history that precedes the famous Alexandra Grahams Bell's photophone of 1880. In the past decade, the world has witnessed a dramatic increase in the traffic carried by the telecommunication networks. Optical fibre systems provide the means to accommodate this demand in the core and the metropolitan-area network level. However, the fibre has still a long way to go, before it reaches the end users in particular at homes because of the very high installation costs. In such cases broadband wireless networks such as the 4th generation (4G) is the best option that will include a number of different complementary access technologies rather than a single technology, with the ultimate goal of providing omnipresent connectivity, ranging from high-mobility cellular systems to fixed and low-mobility indoor environments. Today's Radio Frequency (RF) based networks may be able to support one or perhaps two high capacity users per cell. Multiple high capacity users could only be serviced by deploying a similar number of systems, all within the same locale. This would create a situation where the multiple cells almost completely overlap, which then raises concerns with regards to interference, carrier re-use, etc. In contrast, optical wireless could deliver the necessary capacity to each user using a single or multiple wavelengths. Indeed, optical wireless is a future proofed solution since additional capacity (un-regulated bandwidth far beyond the capabilities of RF) could be d elivered to users as their needs increase with time. It is argued that optical wireless communications (indoor and outdoor) has a part to play in the wider 4G vision offering a number of advantages over RF, such as: abundance of unregulated bandwidth: 200 THz in the 700-1500 nm range, no multipath fading, high security, higher capacity per unit volume (bps/m3), cost effective at rates near 100 Mbps, small cell size.

Optical wireless technology will be complementary to the RF technology supporting a number of applications such as:

• Rural and less developed regions
• Last mile access networks
• Densely populated cities: linking tall buildings at short (outdoor)
• Large campuses (indoor and outdoor): such as universities, hospitals, galleries, etc.
• Disaster recovery situations (outdoor)
• Inter-satellite (outdoor)
• Special events.