A cordless communication system includes a plurality of cordless communication devices, a plurality of connection units which couple the cordless communication devices and communication lines, and a control unit which controls connections between the connection units and the cordless communication devices. The control unit includes a retrieval range specifying part for specifying idle channel retrieving ranges within which connection units which are idle respectively retrieve idle channels so that the connection units which are idle share a retrieval procedure for retrieving idle channels from all the channels, and a control part for controlling the connection units so that the connection units which are idle retrieve idle channels within the idle channel retrieving ranges specified by the retrieval range specifying part.
A communication method in a cordless telephone system having a base unit with which a plurality of portable units can be registered, and a portable unit registrable with a plurality of base units. In the method, if the base unit goes off-hook for requesting a call, a busy signal is sent to all the portable units registered with the base unit. If the call is terminated in the base unit, a call termination signal is sent to all the portable units. Upon reception of the busy signal, a portable unit stores data indicating that the base unit is busy in a selection table of a memory. For initiating a call, the portable unit sends a call request signal to a primary base unit listed in the selection table if the primary base unit is not busy, and otherwise, to another idle base unit. When a call termination signal is received from the busy base unit, the busy state indicating data is deleted in the selection table.
An access point device and a technique for the access point device is for setting a channel of the access point device. The method for setting the channel of the access point device includes: a peripheral search for receiving information from peripheral access point devices, and searching channel numbers used by the peripheral access point devices; an optimal channel number decision selecting one of the channel numbers except for the used channel numbers, and deciding whether the selected channel number is an optimal channel number; and a channel setting for setting the selected channel number as a channel number when the selected channel number is the optimal channel number. As a result, the optimal channel number is automatically set so that the access point device can perform communication without being interrupted by the peripheral access point devices.
A free channel selector for selecting from a plurality of channels an optimal channel for establishing radio communication. The channels may be selected by a radio frequency (RF) module for outputting sampled signals carried on that channel. The selected signals are digitized and provided to a peak detector. The peak detector compares the strength of the signals from the various channels. A memory device, having an array of cells, is provided for storing values representative of the sampled signals of each of the plurality of channels, each of the stored values being stored in a cell having an address indicative of the channel on which the signal represented by the stored value is carried. A stored value corresponding to the lowest signal strength is selected as being the free channel. Communication will then occur over that channel.
A cordless telephone set having a base unit and handset units and enabling communications using a channel selected from a plurality of channels. The cordless telephone set comprises apparatus for storing a specified number of channels selected by the telephone apparatus and storing historical channel use data. Whether or not a channel is unused is determined and channels used with high frequency with the data stored in the first storage are changed to those used with low frequency according to the historical use data. Channels that are stored are progressively specified prior to a start of call and a specified channel is selected, if it is determined that the channel is an unused one.
A base station (5) comprises a base transmitter (6) for transmitting information optically to a plurality of portable stations (1 to 4) at such a predetermined time interval as is designated by portable station designating information. Each of the portable stations (1 to 4) comprises a potable transmitter (7) for transmitting information optically to the base station (5) in response to the transmission, which is designated by the portable station designating information coming from said base station (5), and within the range of the aforementioned time interval immediately after said transmission. Transmissions (ACK1 to ACK4) from the mating portable stations to the base station are individually inserted between the interval periods of the transmissions (REQ1 to REQ4) from the base station (5) to the portable stations (1 to 4) so that the single base station performs optical communications with the plurality of portable stations in a half-duplex time sharing manner.
