Looking for ideas on network upgrade

I have run a small WISP (serves my home/office and some neighbors) for the past 9 years. The AP site is solar-powered, which constrains the envelope a little as far as how much gear can be deployed there. Currently I have an RB600A with three radios (2x SR5 and 1x SR2). One 5GHz radio runs the backhaul to town using Nstreme @ 36Mbit air. The other 5GHz radio is currently used for a P2P to my office (54Mbit air data rate, also Nstreme). The 2.4GHz radio drives a single 90 degree sector panel that serves the customers. CPE is mostly Tranzeo except for one customer that has MT. Customers are all within 4km of the AP.

Although this setup has worked well for us, delivering 1-2Mbit (4 in a pinch) service to the customers, we’re finding that users are now trying to stream video (Netflix, Hulu etc). Although they can do this one at a time, if two or more were to try watching a movie…

My question is this: what’s the best way to ‘upgrade’ this setup so we can offer customers the choice to either stay with the current service, or switch to a faster service that will accommodate modern streaming use (let’s say 3 concurrent 3Mbit streaming CPE)?

We need to leave the existing 2.4GHz radio in place to serve legacy customers. Ideally the ‘new’ customer service would also use 2.4 since we can re-use existing antenna installations at some of the customer sites. But I’m not sure if the level of performance I’m looking for can be achieved on 2.4. I’m assuming that there’s no way to run a high performance service on the existing 2.4 radio and antenna because the old 802.11b CPE will prevent use of .g (we have at least one CPE that I know falls over if it sees the AP advertise .g, so it is configured as .b only at present). Last time I checked, .g did not work at the distances we have to the CPE anyway, but perhaps that situation has changed over the years.. So – what are my options for delivering high speed service over 2.4 these days ?

Could I convert the existing 5GHz P2P radio that serves my office into an Nv2 AP ? What kind of aggregate throughput could I expect from that ? This approach would avoid the need for an additional radio and antenna at the AP site, which is a definite plus, but I’d want to still be able to deliver at least 10Mbits of clean capacity to the office (today we can do 17Mbits but 10 is probably sufficient).

Any other ideas most welcome. Thanks.