Short answer: I have no ideabla bla bla throughput bla bla bla. Whats the LATENCY like???
Of course, the bottle neck (and it's more of a stop-valve in this scenario) is ICASA and whether they will grant a license for this network. I'm guessing soon enough (if not already) that you guys might have it since it's very easy to blame a test if something goes wrongThe article may have implied that I am leading this initiative. I'm not. I just sit on steering committee of the project, that's all.
I should also have said that the project is entirely dependent on the good will of ICASA with whom we have not yet applied for a test license for this project. They have been very positive about TVWS so far and very ready to engage but it is still early days.
If you are looking for more information about TVWS, here is a link to a good background article.
More than likely not. They'll be using dynamic spectrum access but I highly doubt they'll propagate the intelligence upwards to the network level. I think what they'll be doing is like the FCC did in the states and that's using a database containing spectrum information for a geographic location. In other words, the device connects to the database (probably through the mobile network) and obtains information about which channels are available for use in its location.More technical details please!!! Are they using cognitive network technology?
TVWS is actually a precursor to a future technology called cognitive radio. Currently TVWS serves as a quick fix for the problem of spectrum crowding. As it sits, the licensed spectrum is unused a large percentage of the time by its licensees (figures can be as high as 85%, or 100% with the case of Sentech in SA). TVWS technology aims to exploit the unused TV channels (due to interference mitigation requirements as mentioned by Wimbo) since they're large and easy to exploit. Once the digital dividend is fully open though, we'll still likely license it in the old fashioned, exclusive way (regulatory authorities do not like thinking ahead) and we'll back at the problem of "companies have spectrum they don't use and the ones that need it aren't allowed to use it"I was about to ask about licensing issues, I guess this answers my main question - we still need the cooperation of ICASA, a major hurdle, as positive as you may want to be.
My other question is how does this affect the migration to DTT and the digital dividend. The way I understand it, TVWS will be making partial use of (future) digital dividend spectrum which will eventually sold/auctioned off in chunks, making TVWS a wasted exercise. Right?
1) depends on how it's duplexed, purely a system design parameter (unless they love to repurpose 802.11 transceivers, like all WAPA members do )it all sounds good in theory, but what about the uplink? I imagine everything needs to go through Telkom in the end? Unless you have some kind of infrastructure dedicated to this project.
10mbps for users is great, but as we currently see with Telkom... sharing a 155mbit ATM uplink over 5000 users doesnt work
Those numbers look closer to the propagation delay (one direction) rather than the round trip time (RTT) that is usually considered when looking at latency. And even then... those numbers are optimisticThe longer the cable, the higher the latency. That's why we're talking about say 40 mS for Paris to Washington and 75 mS for RSA to Europe over SEACOM, compared to over 300 mS for a satellite connection.
This is actually a myth as I was discussing a few days ago. The only time that you will see significant forwarding delay on a router is when its congested and the buffers are filling up.However, this unfortunately isn't the only factor. If there're one or more routers between the two Hosts, then the latency is increased by two more factors: the time it takes a router to process a packet, and the time the packet sits in a queue on the router waiting to be processed.