4.9 GHz Hot Standby

Has anyone come across a TDM based 4.9 GHz solution that incorporates hot standby? I have yet to see one which I find to be odd given that the 4.9 band is allocated for Public Safety, most requiring true reliability via means of hot standby.

There are a few products out there that boast hot standby configurations by installaing parallel devices and using different polorazations for the antennas, but this is not true hot standby. The most attractive product I have come across as been the the Exalt 4.9 solution.

Any thoughts or comments?

What about two radios live at all times and configure the switch to aggregate two ports. One link dies, the other is up.

Then you can go with something a little less costly like the Trango 4.9 solution.

This will be passing PDH-type traffic, e.g. T1 frames with each DS0 carrying voice and/or tones to key remote base stations. The radios I have been looking at do contain Ethernet ports (who doesn’t ?) and are TDM based as opposed to OFDM. The Exalt system incorporates GPS for Tx and Rx cycles like Canopy. This type of system will require external Multiplexers to frame everything prior to passing it to the RF.

I haven’t seen anything of the sort like that for 4.9. My plans were if ever asked for hot-standby, is to run pairs of radios but run RSTP on the links to simulate it. Thus far however no one has asked for a hot-standby. The Alcatel stuff we use has hot-standbys built in…dual everything inside the shelter in the radio shelf itself. Those are 6-gig radios though.

There might be vendors out there willing to retune their gear for 4.9. Some good units have cavities and all the REAL microwave equipment components, instead of the so-so towertop units that we are all familiar with, which lack all of the goodies of a real microwave system.

The stuff we do 4.9 with is Airaya or Alvarion. Mot has some 4.9 gear now too, that supposedly is pretty good stuff. I seem to remember it was OFDM like the rest of the world, but based on the Orthagon platform. I’d feel comfortable deploying Mot’s solutions. There are also some new deals coming down the pipe for 4.9 supposedly, like mesh and what not from what i was told.

I’ll refrain from speakin about other vendors gear but feel free to pm me.

What are you seeing for range with your 4.9 deployments? The band is very sensitive to fresnel zones, and foliage it seems. It’s not as bad as 5.8 but it tends to be pretty cranky. The nice thing is the band is pretty quiet so you can get away with a lot more than normally you would.

Thanks for the reply. The “real” microwave equipment you speak of is the type of equipment needed for this application. We have engineered and installed real microwave solutions for customers before, the most recent vendor was Microwave Networks. They make some nice gear in 6, 11, 23 GHz etc. The mux equipment I have experience with is RAD. The RAD gear has a pretty complex CLI but once you are used to it, it is quite easy to configure and maintain.

I spoke to a representative from Exalt a few months back. He told me that their company has the hot standby feature implemented in software, but still need to add an RSU (Redundancy Switching Unit) hardware device into the platform. So, who knows when that may be. Exalt makes a tri-band solution (2.4, 5.2 & 5.8) which incorporates Hot Standby, but no 4.9. Knowing that they have an existing solution with HSBY, I would hope the day will arrive shortly where it is introduced to their 4.9 product.

As far as the distance at 4.9, I am not able to comment. This will be our first deployment. A customer has a 4.9 link on our tower but it is only shooting to an adjacent tower, I would say no more than 75 yards away.

Thanks again for the reply.