Monday, September 26, 2011

DECT repeater

In the last blog, I wrote something about how far the DECT signals typically go. There are two scenarios, where the base station cannot cover the area. The first one is in large buildings, for example hospitals or hotels where you need to install several base stations to cover it all, and potentially also a DECT handover if you don’t want to loose the call when walking down the stairs from one floor to another. The second scenario is where you need a “booster” that juts extends the reach of the signal, and in that case you would use a DECT repeater.

As the name suggests, what the repeater does is to repeat the signal. This is not “boosting” the signal, because the signal strength of the repeater is similar to the strength of the base station. It just repeats the signal, so that the traffic that occurs in one timeslot will be copied into another timeslot, so that the base can talk through the repeater to the handset. For example, if you have a long hallway, this is a simple and elegant solution to provide good signal strength everywhere. The repeater works from the handset point of view like a handover solution, because when the handset goes from one end of the hallway to the other, it will eventually perform a handover somewhere in the middle.

You can also add multiple repeaters to a base station. However, there are limits. First of all, because the number of timeslots is limited and they overlap to a certain extent, your timeslots will be eventually full and that’s it. The other problem is that once you have too many repeaters, you are increase the total jitter in the system, possibly to the degree that the whole system becomes instable and then calls drop like flies when you use that bug killer spray. I don’t know what exactly the limits are, but I would be conservative with the number of repeaters that you can safely add to the system. If you need 16 repeaters to cover your area, you probably need another solution and also you probably need more than the 4 concurrent calls that you can have with the m9.

The other problem is encryption. Because many vendors have come up with their own encryption protocols, you cannot connect any repeater to any base station. You have to either turn encryption off or you have to use a pair of base and repeater that use the same encryption protocol. For the snom m9, we have added a special version that deals with the problem (this will be called “snom m9r”, as the name suggest this has something to do with the repeater).

The ultimate goal is to have a system where you can handover from one base to another, without the need of repeaters. Right now, such systems are available; but with a hefty price tag. In many cases one or two properly set-up repeaters can solve the problem as well and the whole solution is cheaper and easier to install.


  1. Repeaters are the low cost alternative to a real DECT based Call Handover/Roaming solution. However bear in mind that repeaters come with scalability limitations compared to a Multi-cell solution which can be extended to 256 base stations and beyond. Having said that, for small to medium sized coverage areas, Repeaters would certainly make sense over multi-cell setups (specially if you compare the deployment costs).

    snom m9 currently does not support DECT repeaters due to hardware limitations. However this limitation will be addressed in the next generation hardware of the product, which the author has referred to as "snom m9r"!

  2. I think this is disgusting. I purchased a large number of Snom M9 base stations and handsets on the promise that "We will release a repeater by the end of 2011" Here is the end of 2011, still no sign of a repeater. Pretty strange, such a simple piece of equipment to build.

    So here we are a year later with an announcement from snom that the Philips Vega chipset used in the base stations does not support repeater functionality so there will be no repeater unless you purchase all the equipment YET AGAIN, this time the snom M9r.

    I wonder how much money they spent on a team to try to develop the repeater for the current snom M9, I mean, they did spend a year trying to develop one before the end of 2011 right?
    Oh, incorrect again. Of course, snom knew right from the very beginning that the Philips Vega chipset did not support repeater functionality. That's why they tried so hard to promote the system as a multiple base system, without the need for repeaters. Unless of course, you wish to roam from one base to the other (WHICH OF COURSE WILL DROP YOUR CALL!)

    That's my final ever purchase of snom equipment. In fact, I'm so disappointed in the company that we have gone ahead to begin manufacturing our own products to use with our services. When ready, they'll blow snom and Gigaset right out of the water and tear them apart. Let's hope they hit the shelves one day and we can all watch snom suffer instead of us!

  3. Mr. Anonymous: I understand your concerns but let me be honest with you. When snom started out the snom m9 project, the focus was to deliver an IP DECT phone independent of the monopolists in the DECT industry. I don't need to name names but i think you already know that almost 90% of the DECT equipment in the market is being supplied by 2-3 major vendors and it is difficult to break free from their hegemony. Ultimately what this means for the end user is a slower response time for customer issues and lags in staying abreast with upcoming and current technologies in the industry. For the same reason our aim was to offer an IP DECT phone over which we could have total control so that we could meet customer demands in terms of software and technology more efficiently. But given the background i've detailed, we were not left with a lot of choices as far as the hardware was concerned. And the current m9 platform was all we could work with.

    The recent availability of improved platforms has enabled us to offer an improved snom m9 product starting next year which will take care of most of the customer concerns relating to hardware including Repeater functionality. The new hardware will also make sense for non-repeater users alike because it has an improved handset hardware (Speaker etc.) and more memory. Once again let me stress the fact that it is not our goal to rip people off by making them buy hardware twice , but to improve and enhance the current hardware to meet customer satisfaction.

  4. Any release date yet for the Snom M9r ?

  5. M9r will be available in the US by April 2012.

  6. Is that the same date for the UK?

  7. Please any release date for the Snom M9r in the US

  8. So here we are in September 2012. All the talk of m9r being able to work with a repeater is great. I have an m9r. I do not have a repeater. I am trying to solve a signal issue with a customer in part of their business premises. If Snom does not have a dect repeater what other devices can be used to provide the functionality?


  9. I've had an m3 installation for several years, and the batteries are all dying. Will the m9r handset and base station work with my existing m3 repeaters, or will I need to wait until native m9r repeaters are available to upgrade?


  10. The big topic with the repeaters is the encryption. You probably have to turn encryption off on the DECT link to get the repeater working. There were some "rumors" that the m9 repeater has finally made it, but I have not seen any yet... So it might be worth a shot to try to use the m3 repeater with the m9/m9r.