An advantage of wireless LAN systems is that they can be set up and altered easily as they require no indoor wiring. On the other hand, a disadvantage is that their transmission rate is low (normally one 2 Mbps channel) compared to wired LAN systems which typically reach a throughput equivalent to 10 Mbps. Therefore, in a conventional wireless LAN system, only a single terminal could use the system at the same time.
Using the multiplexing technology developed by KDD called CFO-SSMA, the multiple 2 Mbps radio channels do not interfere with each other. Another technology, demand assignment, allows more than one user to use the system simultaneously. Combined, these technologies allow the LAN system to multiplex up to nine 2 Mbps channels, or a total of 18 Mbps in throughput. With the technologies, it is possible to set up a high-speed wireless LAN system that is as fast as a wired LAN system and realize high-speed data transfer and video transfer within the LAN. KDD has developed these technologies based on the radio technology that it has fostered over many years. The company has received patents on the CFO-SSMA technologies in Japan and the United States and is applying for a patent on the frequency assignment method.

Using the technologies, KDD has developed a multi-channel high-speed wireless system prototype that allows transmission of four 2 Mbps channels at the same time. By adding ethernet-compatible interfaces to this system, it would be possible to connect by radio some 20 to 30 terminals to a single LAN or connect LANs by radio. The new system not only eliminates the need for rerouting cables when changing the network layout, but allows notebook-sized PCs to be used anywhere on the premises, for example. Consequently, it offers far greater economy and convenience compared to conventional wired systems.

KDD plans to refine the multi-channel high-speed wireless LAN system and point-to-point high-speed wireless system, which connects two fixed points, and market the systems through KDD Technology Corporation and other subsidiaries starting this fiscal year. KDD expects the systems to be used for many applications including a premise portable terminal information system, inter-building communications, and a local monitor system using video cameras. KDD also anticipates that the technologies will find application as a subscriber radio system for telecommunication services in the future.

(Reference) [LAN] - Acronym for Local Area Network, LAN refers to an intracorporate information and communications network that is formed within a building or compound. LAN unites PCs, printers, etc., each with independent functions, to allow users to share hardware, software, data, etc.
- As opposed to wired LANs that use a cable for the connection, wireless LAN uses radio wave of a certain frequency for the connection. An advantage of wireless LANs is that they can be set up and altered easily as they require no indoor wiring. A disadvantage of conventional wireless LANs is low transmission rate compared to wired LANs.

[2.4 GHz band]
- In Japan, this frequency is assigned for industrial, scientific, and medical use. Besides LAN, it is used for medical equipment, microwave ovens, etc.
- Because this frequency requires low power and its propagation range is limited, it requires no radio license.

[CFO-SSMA]
- Acronym for Carrier Frequency Offset-Spread Spectrum Multiple Access. - The conventional access method allowed the use of only one channel (2 Mbps) in 2.4 GHz band. On the other hand, CFO- SSMA, developed by KDD, is the world's first access method where the multiple radio channels (each one is 2 Mbps) do not interfere with each other. In addition to the introduction of multiplexing, this technology will help resolve problems involved in conventional wireless LAN systems such as transmission capacity and transmission distance.

[Demand Assignment]
- The technology of assigning a radio link to each connection request when calls are simultaneously generated from a number of terminals in radio communications. Compared to conventional fixed assignment, this technology increases usage efficiency of circuits. Demand assignment is used in satellite communications by INTELSAT and INMARSAT. KDD has several patents on the technology.

[Ethernet]
- A network that provides a LAN with a transmission rate of 10 Mbps, for example. Ethernet is de facto standard for LANs that connect a number of PCs, workstations, printers, etc.

Details of this technology are also available on the Internet.
(For the time beings, Japanese version is not available.)
URL: http://www.lab.kdd.co.jp