In building DAS (Distributed Antenna Systems), are fairly straightforward in their technology design. Active based, i.e. single mode fiber based design to passive coaxial distribution fed by either a BDA or BTS. Or where limited coverage passive coaxial distribution. As they were orgininally designed for 850MHz/1900MHz, and 800MHz, these type of DAS designs and implementations have worked in a reliable fashion for what they were intended to. However, when you attempt to utilize 802.11a there are significant issues with achieving the link budget, let alone the cost of amplication for 5.0GHz. It is also very quesitonable if 802.11n (MIMO), will ever work on a DAS. So at the end of day, it may just be best to go back to use the original business model of what a DAS was intended for. Extenet http://www.extenetsystems.com states that they can use HVAC infrastructure as wave guides for the distribution for RF signals, in this case public safety at 800MHz, and could be 850MHz/1900MHz. If this proves out, it is a game changer. Eliminating costly coaxial distribution and dedicated runs of single mode fiber for indoor DAS would drastically reduce costs up front for not only design, CAPEX, and implementations.
