International Business Machines Corporation

Frederic Bernard Lefevre

Frederic J Bauchot

Luc Louis Revardel

Arnaud Lund

Alain Albert Dorel

Francois LeMaut

Roland Amiel

A system and method for controlling the time occupation of signalling frequencies is disclosed, in a frequency hopping system including a plurality of remote stations communicating under control of transceivers with a transceiver of a base station, such communication being performed over a shared medium through a sequence of frequency hopping periods in a plurality of operating frequencies. The method consists in selecting a set of signalling frequencies among the operating frequencies, and interleaving signalling messages transmitted on each signalling frequency within each frequency hopping period to allow a remote station to enter the network for the first time or by re-acquiring synchronization, by scanning each signalling frequency for receiving a signalling message. The method preferably employs structure and techniques for averaging over the sequence of frequency hopping periods the time occupation for data and control messages transmissions on the plurality of signalling frequencies according to the time occupation for signalling messages transmissions.

Method and system for controlling the time occupation of signalling

In a multicellular communications network system comprising base stations and a plurality of remote stations, a remote station listens for frames of information emitted by the different base or remote stations, in order to insert the network. The base stations and the remote stations comprise means for emitting the frames of information using a sequence of changing frequency hops of different operating frequencies. The remote station determines a set of 'n' operating frequencies (Fi), from which it sequentially listens for a fixed period of time equal to 1/n of the frequency hopping period (FH) of a base station. When a frame of information is received by the remote station during one of the fixed period, the information is collected and processed in order to select the base station for attachment.

Method and an apparatus for attachment of a remote station to a base

A Medium Access (MAC) Protocol is utilized for wireless access, preferrably over a radio frequency channel, for a plurality of remote stations to a base station on a LAN. The MAC protocol is based on a reservation scheme for user data traffic and a random access technique for control and signalling traffic. There is a time division frame structure in which time is slotted. Time slots are grouped into variable length periods. The variable frame structure consists of a frame header followed by interleaved periods of different types (type A, B or C). Type A periods are allocated to the outbound channel which is used for data transfer from the base station to the remote stations. Type B periods, are allocated to the inbound channel that is used for contention-free data transfer from the remote stations to the base station. Allocation of the data slots in the A and B periods is performed by the base station. Type C periods are reserved to the control channel used for transmission of reservation requests and data from the remote stations to the base station in a random-access contention mode using a slotted Aloha protocol. The duration and sequence of periods may be varied by using a technique for interleaving periods of different types. The base station estimates the number of actively transmitting remote stations utilizing feedback information from the remote stations. This estimate is broadcast to the remote stations as control indicia to control their transmission attempts in C slots, thus yielding high transmission efficiency.

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Cagnes sur Mer, France

Frederic Bernard Lefevre