Monday 16 November 2009

The Secret world of WiMAX Femtocell

We have talked of WiMAX femtocells before and since I have mostly been focussing on 3GPP standardised Femtocell, I thought it is wise to focus on WiMAX femtocell and learn more about its terminology and implementation. Whenever possible, I will draw comparisons with the 3GPP femtos and try to provide more insight if I can.

Surprisingly I found it difficult to find the information on WiMAX femtocells. I am sure its not because no one is interested in the technology but its more because of the standards not being available in public domain. An old article on Think Femtocell informs us of the initial players of WiMAX femtocells. I havent tried digging in who is doing what in the WiMAX femtocell world, so if you are aware of potential players, feel free to highlight them via comments.

In WiMAX terminology, femtocells are known as femto base stations (BSs) or WiMAX femto access points (WFAPs). They are intended to serve the same purpose as the 3GPP femtocell that I have mentioned time and again. WiMAX as a technology is intended for data and voice can be an OTT application. In a way its a disadvantage for this technology but can be considered as an advantage as it doesnt have the baggage of old Circuit Switched system.

Another thing that I should clarify here is that WiMAX is intended to operate in licensed spectrum and so are the WFAPs. All femtocells start playing important role when high data rates are required and when the operating frequencies are high. Higher frequencies means lower penetration inside homes and the signal inside the offices can be easily enhanced with femtocells (or for that matter picocells in big buildings).

The WiMAX Forum has commenced the development of femtocell standards in two phases. The first phase is based on IEEE 802.16-2009 (aka 802.16Rev2) and system profile Release 1.0 or Release 1.5, so no change in the air interface standard or legacy MS is required to enable basic femtocell deployments. Some optional software upgradable enhancements in the MS may be used to enable additional femtocell functionalities only for such femto-aware MSs. The network framework to support femtocells in phase 1 is being developed in the WiMAX Forum as part of Network Working Group (NWG) release 1.6. The complete end-to-end femtocell specifications are expected to be finalized by the end of 2009. The second phase of WiMAX femtocell development, which brings additional functionalities and more optimal performance, will be introduced in system profile and network Release 2 based on the 802.16m air interface. The evolution to phase 2, which is expected to be completed by 2011–2012, enables enhanced femtocell systems with 802.16m MSs’ advanced functionalities while continuing the support of phase 1 legacy MSs with basic functionalities. Femtocells are expected to play an important role in terms of cost-effective delivery of new services, such as multimedia, gaming, social networking, and other demanding applications with the high quality of service (QoS) level expected by users in an indoor environment. However, femtocells are in an early stage of development and have some technical challenges to overcome.

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