EP0650274A2
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EP
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Radio communications systems with fault tolerant frequency hopping synchronization
Assignee: International Business Machines Corp
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Filing: 1994-09-23
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Granted: —
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Expires: 2014-09-23
Abstract
Abstract A method for use in multicellular communication network system of the type having base stations and a plurality of remote stations. The method achieves reliable and fault tolerant synchronization between the stations in a call when a frequency hopping technique is used. The method includes steps for acquiring the frequency hop sequence by remote station and tracking the frequency hop sequence after acquisition in order to stay in synchronism. The method also provides for recovering from loss of synchronism and for staying in synchronism.
Inventors
- 👤 Frederick J. Bauchot
- 👤 Chia-Chi Huang
- 👤 Ilan Kessler
- 👤 Kadathur S. Natarajan
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-05 21:03
CPC Classifications
H; H04; H04J; H04J13/00; H04B; H04B1/00; H04B1/69; H04B1/713; H04B1/7156; H04L; H04L7/00; H04L7/04; H04L7/041; H04L7/043; H04B2001/71563; H04B2001/71566
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
159 words
A method for generating, acquiring and tracking consecutive frames for synchronization during a transmission in a multicellular communications network (24) system having base stations (26, 28) and a plurality of remote stations (10, 12, 14, 16) which incorporate a technique for frequency hopping wherein said base stations (26, 28) transmit information to remote stations (10, 12, 14, 16) using a sequence of changing frequency hops of different carrier frequencies, said method comprising the steps of: Step 1 generating frames of data to be transmitted from each of said base stations (26, 28) to said remote stations (10, 12, 14, 16), said frames including a header portion (AH) and a data transfer portion (A), Step 2 incorporating frequency hopping control information into said frame header portion (AH), Step 3 transmitting a plurality of said frames from said base stations (26, 28) to said remote stations (10, 12, 14, 16) using a sequence of changing frequency hops of different carrier frequencies.
Claim 2
Dependent Claim
75 words
A method according to claim 1, wherein said step 2 thereof of incorporating frequency hopping control information into said frame header portion (AH) includes the steps of incorporating the address of said base station (26) within the network (24), incorporating the time remaining in said frequency hop being used, incorporating the frame length of said frame, and incorporating a list of the next hopping frequencies to be used in said sequence of changing frequency hops.
Claim 3
Dependent Claim
84 words
A method according to claim 1 or 2 further including a step 4, wherein a remote station (10) performs a technique for acquiring said plurality of frames transmitted from said base station (26) in Step 3 by listening to frames of information transmitted from different bases by repeatedly listening to different frequencies for fixed periods of time equal to a frame length, and selecting a home base from said different bases listened to by locking into the frequency hopping sequence of said selected base.
Claim 4
Dependent Claim
60 words
A method according to claim 3, wherein said remote station (10) monitors and records indicators from said transmitted frames from said different bases, said indicators being the received signal strength indication (RSSI), the header observation rate (HOR) and the load factor (LF) from said different bases, and wherein said selected home base is selected in accordance with said indicator criteria.
Claim 5
Dependent Claim
108 words
A method according to claim 4 including a synchronization technique wherein, after selecting a home base in said acquiring step of claim 4, said method performs a frequency hopping sequence tracking technique, said frequency hopping sequence tracking technique including the steps of acquiring the said frequency hopping sequence including the next frequency hop, seeking the header information in the next frequency hop transmitted by said selected home base, upon finding the header information said remote station enters a SYNC state of operation, upon not finding the header information after seeking for a predetermined number of frequency hops, said remote station enters an OUT OF SYNC state of operation.
Claim 6
Dependent Claim
95 words
A method according to claim 5, wherein, when said remote station is in said OUT OF SYNC state in said frequency hopping sequence tracking technique, said remote station switches to a given frequency for a given period of time equal to or greater than the length of a frame, and wherein said remote station monitors the header information of frames transmitted from a series of other bases of said network (24) and selects another base as a new home base when paid SYNC state of operation is not achieved with a selected number of attempts.
Claim 7
Dependent Claim
83 words
A method according to claim 6 further including a technique for fault tolerant frequency hopping synchronization wherein a frequency hop table is initialized and stored in a memory table by storing the separate frequencies in the said frequency hop sequence, said method comprising: - listening at said remote station (10) for a specific frequency referred to as a default frequency - updating said memory table based on changes in the frequency hop sequence data in said frame headers transmitted from said base stations.
References Cited (Backward Citations)
No citation records indexed.
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