Network Capacity

Chapter 2 discussed enabling technologies and advances that were adopted for LTE, WiMAX and their IMT-Advanced successors. As noted before, several technologies were sought in order to enhance the capacity of access networks at a cost efficient manner. Without doubt, the choice of multi-carrier access techniques will offer both great flexibility and reliability in such direction. However, it is in advanced antenna and network configurations that substantial capacity gains are achieved. Already, the notion of small cells – through the in-band femtocells or out-of-band WiFi networks – are already beginning to play an important role in today's networks. The importance of small cells in the next few years can be highlighted by estimates of the amount of data they are expected to support −800 million terabytes per month by 2015 [2].

Other advances will come at higher costs, including the use of relaying techniques and cooperative MIMO. As noted in Chapter 2, it is generally understood that such “meshed” wireless communications can provide substantial gains. Relaying, for example, combats path loss and shadowing loss through the breaking down of the wireless link into smaller and reliable segments. Similarly with MIMO, which have shown great versatility in either mitigating interference or enhancing the reliability of the wireless link. And while for some of these advances the limits on possible gains are yet to be figured [5], the practicality of achieving these gains will be slowly evaluated over the next ten years as they are introduced to actual deployments. Certain issues, such as finding deployable mechanisms for resource allocations, remain unresolved. More critically, it will be important to demonstrate that capacity gains made exhibit reliability and cost efficiency.