Yesterday morning, Airvana announced its 16-user, HSPA-capable femtocell and we strongly believe that it is the right solution for operators who want to offer excellent coverage, capacity and services to high-value enterprise customers.
Over the last year, there has been a vigorous debate in the femtocell industry about whether it is necessary to build new high-capacity hardware for the enterprise market, or if it is sufficient to just network 4-8 user femtocells. At Airvana, after talking to our customers - wireless operators – and considering the problem from their perspective we decided to invest in building this product, and are very excited to announce it today.
Here are the top three reasons why in my opinion, high-capacity femtocells are a better solution than grids of residential femtocells for wireless operators.
1 Voice capacity is key to enterprise femtocell business case
For mobile phones to displace desk phones in enterprises, wireless operators must provide excellent coverage, PBX-equivalent features and sufficient capacity.
Based on Erlang B model with 2% blocking probability, a single 16-user femtocell provides 9.8 erlangs of voice capacity or 200 calls during the busy hour, assuming an average call holding time of 3 minutes. Based on the same model, a 4-user femtocell provides 1.05 erlangs of voice capacity, or 21 calls during the busy hour with an average call holding time of 3 minutes. This means that an enterprise would have to deploy ten 4-user femtocells to allow its employees to make the same number of calls as they would be able to with a single 16-user femtocell.
More business users are in big office spaces
Operators need to go where subscribers are. Even though US Census information shows that majority of office premises have 10 people or less, the same data shows that almost 70% of people work in offices with more than 40 employees. This means that any femtocell solution chosen should be able to easily serve offices with 100 or more subscribers.
Simple to deploy and operate
A single 16-user femtocell capable of delivering 9.8 erlangs can support an office with almost 100 subscribers, assuming each subscriber uses an average of 0.1 erlangs during the busy hour. This equates to an office with 200+ employees (assuming that the operator providing the femtocell has 50% of the wireless subscribers in that office)
This means that for in a vast majority of offices, all an IT person needs to do is to install a high-capacity, high-power femtocell in a central location and walk around the office with his cell phone to check coverage level. There is no need for complex RF planning or capacity planning. It should be that simple. (see coverage map for 2-storied office building below).
Before I close off, I must add that by arguing so strongly for 16-user (& even higher capacity) femtocells I am not suggesting that inter-femto handovers are not needed. They are essential for office campuses with over 200 employees, and even for smaller offices when femtocells are integrated with PBXs. However, I do believe that inter-femto handovers must be introduced within the context of standards – and at Airvana, we are working on a way to deliver inter-femto handover without breaking Iuh. Stay tuned.
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