Patent US5126076A successfully refreshed from Google Patents.
Patent EP0677940A2 successfully refreshed from Google Patents.
EP0677940A2
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EP
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Handoff monitoring in cellular communication network using slow frequency hopping
Assignee: International Business Machines Corp
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Filing: 1995-04-03
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Granted: —
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Expires: 2015-04-03
Abstract
Abstract Methods for 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 mobile stations can communicate with a base station, 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 duration and having a fixed frequency different than another channel. The handoff method employs structure and techniques for determining by a mobile station that the quality of transmission between it and a current base station has degraded below a predetermined performance level, structure and technique for said mobile station to listen to each of successive frequency channels for a duration substantially less than said fixed duration of a channel until it senses a transmission from another base station, and structure and techniques for transferring control of said mobile station to said another base station in response to the sensed transmission.
Inventors
- 👤 Chia-Chi Huang
- 👤 David Frederick Bantz
- 👤 Frederic Bauchot
- 👤 Kadathur Subramanya Natarajan
- 👤 Anand Narasimhan
- 👤 Michele Marie Wetterwald
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-29 06:55
CPC Classifications
H; H04; H04B; H04B1/00; H04B1/69; H04B1/713; H04W; H04W36/00; H04W36/24; H04W36/30; H04W36/302; H04W24/00; H04W36/08; H04W84/00; H04W84/02; H04W84/10; H04W84/12
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
355 words
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 2
Dependent Claim
69 words
The method according to claim 1 wherein said Step 1 includes each of said base stations in said network generating and transmitting a wireless signal composed of a cyclic time sequence of frequencies hops in a superframe wherein each hop is of the same duration and length, wherein said transmitted wireless signal includes header information including Received Signal Strength Indicator data, Header Observation Rate data and Load Vector data.
Claim 3
Dependent Claim
38 words
The method according to claim 2 wherein, in said Step 2, said Received Signal Strength Indicator data is sampled by said mobile stations at multiple different transmitted frequencies and the mean value of said sampled samples is measured.
Claim 4
Dependent Claim
37 words
The method according to claim 2 or 3 wherein in Step 2 said Header Observation Rate data is the number of transmitted headers received correctly by said mobile station divided by the total number of possible headers.
Claim 5
Independent Claim
29 words
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
Independent Claim
58 words
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 7
Dependent Claim
57 words
The method according to claim 6 wherein, in Step 3, said control of said mobile station is transferred by handoff from said home base station to another base station when said Received Signal Strength Indicator data and said Header Observation Rate data transmitted from said home base station decrease in strength and quality below a selected value.
Claim 8
Independent Claim
38 words
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.
Claim 9
Dependent Claim
37 words
The method according to claim 7 wherein frequency hopping signals in each cell of said plurality of cells is loosely synchronized with the frequency hopping signals of some or all of said other cells in said network.
Claim 10
Dependent Claim
35 words
A method according to claim 7 wherein frequency hopping signals in each cell of said plurality of cells is not synchronized with any of the frequency hopping signals of said other cells in said network.
References Cited (Backward Citations)
No citation records indexed.
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