I'd really like to hear some success stories from people using Name brand 900Mhz OFDM, compared to non-OFDM.. Or more importantly, if anyone has had bad experience with Name brand 900Mhz OFDM, compared to non-OFDM..
I'd also like input from Name Brand OFDM 900Mhz manufacturers regarding what embedded filering they might have in their radios, to combat noise which is just about everywhere with 900Mhz. Let me explain.... I recognize in a noise free environment, it likely works well, but I'm also concerned with the amount of after-rain fade 900Mhz has, and what that does to OFDM and higher QAM modulations that require higher SNR budgets. Over the last 5 years, I of course have evaluated ALL non-OFDM 900Mhz products. I've done most of my OFDM testing with ALL the OEM (Atheros mPCI) brand 900Mhz products. But I avoided spending the big bucks on Name brand OFDM gear, just to do Demos. But in my Live Testing, I'm regularly running into quality issues with the Oem OFDM products, and the stories all end the same. Eventually the final solution is I put a Trango DSSS 900Mhz sector in its place, and then I finally get consistent quality and gain a happy customer. Since the beginning of time, Trango had always been a strong 900Mhz product to "get the job done" because its ability to work in high noise enviroments, due to its high quality built-in filtering, which is near equivelent to a Cavity Filter. In my experience, I've successfully run quality Trango links at receive strengths lower than the scanned noise floor, where as with Atheros running at the noise floor is a formula for prompt dis-association and sporatic high latency, even w/ the spec sheet showing embedded filtering. At first, I questioned the OEM OS that included the Atheros, but I've seen similar results with all OEM OSes. Please recognize these comments are not mean to bash any product or promote any specific product. We successfully use Atheros OEM systems in many locations also. So what I'm trying to establish is... Has my experience been fairly compairing DSSS to OFDM, or.... Should the real comparison be about the difference between high quality gear versus low budget lower quality gear? Is there an equivellent to a Trango 900Mhz (quality against noise), in OFDM? Has anyone taken a challenging 900Mhz DSSS deployment (Canopy/Trango/First-gen Waverider) and successfully upgraded it to OFDM 900Mhz with out loosing significant amount of customers and/or coverage? And if so, Have you successfully been about to get three Horizonal sectors colocated? With Trango, we were able to get three horizontal sectors colocated, wth minimal self-interference as long as we used Titlek high quality antennas, and had about 10 feet min verticle seperation between them. I see that it would be a tougher challenge to accomplish the same with OFDM that required higher SNR. Sure the 900Mhz OFDM looks good on a spec sheet or likely good for PTP links, but now that its 6 months to a year down the road, whats the real world take for PtMP cell sites? Tom DeReggi RapidDSL & Wireless, Inc 301-515-7774 IntAirNet - Fixed Wireless Broadband -------------------------------------------------------------------------------- WISPA Wants You! Join today! http://signup.wispa.org/ -------------------------------------------------------------------------------- WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/
