Over-the-Air: Dynamic or Adaptive Microcell

Dynamic microcell over-the-air architectures take a different approach than static architectures. The goal of dynamic architectures is to use what is known as radio resource management (RRM; some vendors use similar terms) to adaptively configure the channels, power levels, and other settings of the access points.

The reason for transitioning from a stable network to one that is constantly in flux is to attempt to avoid some of the problems inherent in larger 802.11 networks, mentioned in the following sections. The key observation is that radio resources exist and need to be monitored somehow. Broadly, radio resources can be thought of as wireless network capacity, and they are reduced by interference, density, and mobility of wireless clients. The following sections, especially "RF Primer" and "Radio Basics," will shed light on the specifics of what impacts these radio resources.

Dynamic architectures attempt to handle the problem by constantly measuring the various fluctuations in load, density, and neighboring traffic, and then making minute-by-minute adjustments in response. The main tools in the dynamic architecture's arsenal are, as before, choosing channel settings and transmit power levels.

Dynamic architectures end up creating an alternating assignment of channels, in which every access point attempts to chose a different channel from its neighbors and a power level low enough to avoid providing too much duplicated coverage.

The advantages of dynamic radio resource management is that the network is able to avoid situations where static networks completely fail—for example, dynamic networks can continue to operate (albeit with reduced capacity) when a microwave oven is turned on, whereas static networks may succumb completely in the area around the interference. The main disadvantage, however, is that the network and its associated coverage patterns are unpredictably changing, often by the minute. This leads to a necessary tradeoff between the disease and the cure. Thus, dynamic systems provide the expert administrator with the ability to go in and turn down the aggressiveness of the adaptation, providing a choice between a more static network or more dynamic network, allowing the administrator to choose which benefits and downsides are best suited for the given deployment. You will find that many voice mobility networks have disabled many of the adaptive features of their networks to ensure a more consistent coverage.

Additionally, the smaller and changing cell sizes, along with the wide array of channels that end up being used, leads to issues with handoff that directly affect voice mobility. To help mitigate these problems, network assistance protocols can be used to increase the amount of information that clients, who decide when to hand off and where to hand off to, have at their disposal.