Plenty of free advice on this list, no problem there. Two general rules are RF does not go through dirt (aka hill), period. And High frequencies like 5.x Ghz does not penetrate hard surfaces like brick and cement, and does not really penetrate anything well, so does not penetrate wood either unless very high power.
If you need to make a Non-Line-of-Sight shot and shoot through a structure you are going to have to use 900Mhz. However, there are alternatives, such as reflection. OFDM's core benefit was to better accept multi-path reflections to enable a combined signal without interference. It accomplishes this by having a larger time window to allow for all reflected signals of the same data to arrive. If there are other tall building to the side of the building blocking you, with enough gap between them, you may be able to bounce the siganl off of one of them to reach the desired building. However, the first thing I'd question is why you'd try this in the first place. Wouldn't it be better to just mount on top of the taller building? That would be a "relay" site. The tall building would have two radios, each with a panel antenna, one looking down to the shorter buildings in the valley, and one looking to the remote building that will have the gateway to the alternate Internet provider backbone. There is no replacement for gaining a good hassle-free Line-of-Sight connection, if there is a way to accomplish it. Radios are inexpesnive, support afterwords may not be. Where I can understand compromises that may need to be had along the distribution between all the buildings, but its generally not good practice to compromise on a head end critical link that feeds all the others. Tom DeReggi RapidDSL & Wireless, Inc IntAirNet- Fixed Wireless Broadband ----- Original Message ----- From: "Shaddi Hasan" <[email protected]> To: "WISPA General List" <[email protected]> Sent: Friday, May 28, 2010 10:48 AM Subject: [WISPA] Short-range NLOS question > Hello WISPA, > > I'm a lurker on this list that is interested in the WISP industry but > still > learning every day (a lot from you all!), so please forgive my ignorance. > :) > > I run a small community wireless network in a low-income apartment > complex; > we're currently using Open-Mesh > OM1P<http://www.streakwave.com/Itemdesc.asp?ic=OM1P&eq=&Tp=%20>'s > with 7dBi omnis to provide coverage to a couple hundred families in about > 25 > buildings. For reasons that aren't relevant to this discussion and can't > be > changed, we may only place our mesh AP's inside resident's apartments > (this > is an all-volunteer operation, run on a shoestring with a small grant). We > can place AP's outside on people's windows, but we have to be discreet. > > There's one section of the complex that we haven't been able to get > coverage > to. It's in a bit of a depression, so the tops of the buildings in the > hollow are about even with the first floor of the ones higher up. We have > a > gateway for our mesh there, a CLEAR WiMax connection, that never stays up > (we have another one on top of the hill that does stay up, but would that > there were another WISP in our area...), so we are thinking about building > a > P2P link between that section of the complex and our gateways elsewhere, a > few hundred feet away but blocked by part of this hill and several > buildings. > > Because we're on such a tight budget, I wanted to solicit yall's advice > before we made a purchase. We were thinking about using a a couple 5Ghz > Ubiquiti NS's, but I'm not sure how well that will work given the lack of > LOS. We were also thinking about looking for some inexpensive 900Mhz > devices, but I'm not sure if that's overkill for what we're trying to do. > We're not trying to get free consulting from you all, but if anyone has > any > pointers that might help us make a better decision or fix this problem > they'd be greatly appreciated. > > Thanks! > Shaddi > > > -------------------------------------------------------------------------------- > WISPA Wants You! Join today! > http://signup.wispa.org/ > -------------------------------------------------------------------------------- > > WISPA Wireless List: [email protected] > > Subscribe/Unsubscribe: > http://lists.wispa.org/mailman/listinfo/wireless > > Archives: http://lists.wispa.org/pipermail/wireless/ -------------------------------------------------------------------------------- WISPA Wants You! Join today! http://signup.wispa.org/ -------------------------------------------------------------------------------- WISPA Wireless List: [email protected] Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/
