I'm not sure if I am reading this right...it seems like COM DEV believes that 1xEV-DO will be able to provide 1Mbps speeds in a typically loaded system (not throughput but a single user speed). This seems MUCH higher than I would have expected.
Hmmm....they use the word instantaneous. Since 1xEV-DO splits up users in the time domain, maybe I should be multiplying the speed by the percentage of slots that user would have for that one second.
comdev.ca
Q. In a recent article I read they mention the fact that, under real useage, M/ERGY functions at about 800 kbps. They also mention the fact that if there are two users in the same cell, they have to share this speed. In other words, if there are 10 simultaneous users, then they effectively end up with an 80 kbps speed while roaming. Is this correct? (Submitted January, 2002)
A. Remember that M/ERGY is a packet switched network. No one actually occupies a circuit as in the case of a circuit switched network. Everyone is "always on" the network and shares a common pipe into which they insert their data packets and from which they receive the data packets addressed to them. It is thus true that the total capacity of each M/ERGY base station is shared among all the users connected to it. The grade of service the customer actually sees, therefore, varies with the number of subscriber instantaneously transmitting and receiving at the same time. It will also vary according to how the service provider loads the system and the distance from the base station and the speed of the user. (As a mobile user moves faster or begins to go out of range of the base station, more packets will need to be re-transmitted and total throughput will slow toward 100 Kbits/sec). However, I am told that for a stationary user within the specified 3-5 km range of a base station, assuming the operator loads the network as recommended, the minimum instantaneous down link data speed seen by user should be in the order of one Mbits/sec over the last mile link M/ERGY provides. In practice, speed limitations of the Internet backbone may result in slower maximum end-to-end service in the order of 400-800 Kbits/sec or less, but that is an Internet limitation not an M/ERGY limitation. |
