Randall,
Thanks.
We are excited about the opportunities that the limitations of copper wires, cable and fiber have presented us and other wireless providers. Wireless, in the short term, has a major complimentary role. Once 30Mbps mobility is introduced, it could be the vehicle of Internet access for most people.
You are right in assuming that 4524 is 4.5Mbps in the 2.4GHz ISM band.
It is not straight forward to give an unobstructed line of sight range. We do not sell range; rather, we sell path loss which is how much attenuation we can tolerate between the transmitter and the receiver. Under special circumstances, we covered over 67km. We do not recommend networking with a radius larger than 6km. This means that the base station would have an omni-directional antenna emitting power in all directions and that the customer units will use directional antennas pointing to the base station antenna.
On collisions or interference, this is a more complex issue. There is a limit. However, spread spectrum systems are designed to tolerate some interference by other devices. However, we have to distinguish between licensed systems (like cellular telephones) and license-exempt systems like wireless local area networks (LANs). Licensed systems control their destiny and can plan how they will use the spectrum and then the only limitation is the network design. Generally speaking, making the cells smaller yields more capacity (users/square km at a particular bandwidth). License-exempt systems, have the same issue regarding the relationship between cell-size and system capacity; moreover, they have to worry about possible unintentional interference from another (unco-ordinated) user. It is advisable that license-exempt systems be used in rural and light urban areas and that licensed systems be used in dense urban areas. This simple advice almost guarantees no collisions.
Regarding bandwidth binding (or aggregation), we can and we do put base station together and aggregate their throughput. In the UK, we have three units each covering 120 degrees and hence the total bandwidth from the base tower is 13.5Mbps. If we did the same thing in the license exempt band, we may be able to fit 5 channels (22.5Mbps). The units (off-the-shelf) in the license exempt band have three channels (4.5Mbps).
We provide network engineering to help our customers build and design their networks. There are companies that specialize in building networks. Some such companies have managed to use other forms of aggregation (antenna polarization and others) and could possibly achieve many more channels.
Thanks for your continued interest in Wi-LAN.
Hatim |
