Handoff monitoring in cellular communication network using slow frequency hopping

Claim 1

A method of managing handoff in a wireless communication network comprised of a local area network connected to a plurality of base stations, each of which has a geographic area, defined as a cell, within which a plurality of mobile stations having transceivers can communicate with a base station within each of a plurality of said cells, with each such base station being capable of performing bidirectional wireless communication with one or more of said mobile stations under control of a controller, with communication between base stations and mobile stations being performed by frequency hopping, with there being n available frequency hopping channels in a fixed frequency band, with each channel being of a same fixed time duration and having a fixed frequency different than another channel, the base station in each of said cells having receivers each tuned to respective ones of the channels assigned to the cell for receiving signals of the mobile stations within the cell, a cluster of said cells having a network control system through which said cell stations communicate with each other, said network control system operating in conjunction with hand-off apparatus for handing off a mobile station from a first of said base stations to a second of said base stations as the mobile station travels from the first cell to the second cell, said hand-off apparatus being responsive to the strength or quality of signals monitored at a mobile station, said method comprising the steps of: step 1: determining for a given mobile station that the quality of transmission between said given mobile station and a current base station has degraded below a predetermined performance level; step 2: said given mobile station listening to each of successive ones of said n frequency channels for a time duration substantially less than said fixed time duration of a channel until said given mobile station senses a transmission from another of said base stations above said predetermined performance level; and step 3: transferring control of said mobile station by hand off to said another one of said base stations in response to said sensed transmission above said predetermined performance level.

Claim 5

The method according to one of claims 2 to 4, wherein in Step 2 said Load Vector data indicates the number of remote stations communicating with said base station.

Claim 6

The method according to one of claims 2 to 5 wherein in Step 3 said mobile station selects and transfers control to a base station, referred to as a home base station, in accordance with the values of said Received Signal Strength Indicator data, said Header Observation Rate data and Load Vector data received by said mobile station.

Claim 8

The method according to one of claims 1 to 7 wherein frequency hopping signals in each cell of said plurality of cells is synchronized with the frequency hopping signals in all of said other cells in said network.