As always, at Tech Field Day, there is never enough time to get all the tech knowledge transfer accomplished.
I really wanted to learn more from Cambium Networks on their full-suite of Point to Multi-Point and Point-to-Point solutions. But since this was Wireless Tech Field Day – we focused on their ePMP line. These are lower-cost, lower-performance sets of gear. But it makes sense… those in the room, and most of those watching the stream are Wireless LAN Professionals, with a background in Wi-Fi, so focusing on their line of equipment that was based on Wi-Fi SoC’s seemed to be a good choice.
The ePMP line is based on started with a Wi-Fi SoC… then removing the bulk, if not all of the MAC layer and replacing it with proprietary protocols specifically designed for the WISP and PtMP market. They also moved down to the PHY and made major changes there as well – taking out the core of Wi-Fi – the Contention process. This is to allow for the close proximity of transmitters on a WISP tower – if the PHY was basically stock Wi-Fi, very little traffic could happen. The Listen Before Talk process and the randomization of all frames waiting for a clear channel would grind to a halt in this type of environment.
It was fun to learn how they have used GPS to sync their co-located AP’s so they all transmit at the same time, and listen at the same time. There is no coordinated control between AP’s for a ‘I talk, you talk’ type of negotiated slot times. Instead, all transmit together, then pause and listen together. There are still lots of design issues implicated – but by not relying on the standard Wi-Fi protocols, Cambium was able to act more like a Cell Tower, controlling when and how loud the clients respond.
So Cambium was able to take from their experience with more expensive FPGA chips in their higher-end products, and adapt it to run on low-cost Wi-Fi SoC’s. Pretty cool actually!
Though you must be warned. This technology can NOT act as a Wi-Fi access layer device. No non-Cambium gear can attach to their customized network equipment. But, since their AP’s are based on Wi-Fi chips, they can easily re-code an AP that was “Cambiumized” and return it to being a normal ‘follow-the-rules’ Wi-Fi AP. This is great for WISPs – they can use the exact same SKU for the outdoor backhaul link, then hardwire and Ethernet cable from the outside CPE to an indoor AP that was re-flashed to be Wi-Fi enabled and with the same part, do both Cambium and standard Wi-Fi. (just not at the same time – you’ll need one on the outside for the backhaul, and another on the inside for customer end devices to connect via standard Wi-Fi in the home or business)
As Wireless LAN Professionals, we need to learn more about the WISP world of PtP and PtMP – because many of our enterprise customers have needs that are satisfied better with this type of equipment when the Enterprise vendor solutions either don’t fit, or are too expensive for the solution. Quick temporary connections, connecting buildings without cable between them, and near instant solutions while you are waiting for cabling to be installed. All are great situations where you might want to look into these ‘normally WISP’ functions to help augment your enterprise Wi-Fi toolkit.
I look forward to more presentations from Cambium Networks to learn about their high-end PMP and PtP solutions!
Also, take the time to check out this cool online tool to help in evaluating and planing your PtP and PtMP scenarios:
The recorded sessions are available for viewing here: