EP0088647A2
Expired / Lapsed
EP
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System for adjusting a time axis by using a control and an adjustment time slot in a satellite station of a TDMA network
Assignee: NEC Corp
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Filing: 1983-03-10
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Granted: —
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Expires: 2003-03-10
Abstract
Abstract In a TDMA network wherein a central station sends signals towards satellite stations in downward frames (A), each comprising a control time slot (TdO) and speech time slots (Tdl to TdM), and receives signals from one to M satellite stations n upward frames (C) of a like format, the central station checks the number of idle time slots in each of the downward and apward frames. Only when the number exceeds a preselected lumber, one of the idle time slots is selected as an adjustment time slot. The ordinary number given to the adjustment time slot is transmitted in a number field (Nf) of the downward control time slot. Each satellite station generates a time axis indicative of local time slots (D) with a delay relative to the thereby received downward time slots (B). On adjusting the time axis in a selected satellite station, the station sends a short burst (t s ) in the local time slot indicated by the received number field. In compliance with an error with which the burst reaches the central station, the delay is rendered equal to a prescribed frame delay (t e ) minus twice a propagation delay (f d ) between that satellite station and the central station.
Inventors
- 👤 Ryuhei Fujiwara
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-25 01:10
CPC Classifications
H; H04; H04B; H04B7/00; H04B7/14; H04B7/15; H04B7/204; H04B7/212; H04B7/2125; H04J; H04J3/00; H04J3/02; H04J3/12
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
292 words
A time axis adjusting system for use in a radio communication network in which time division multiple access communication is carried out between a central station (11) and a plurality of satellite stations (12) by the use of signals sent in downward frames (A) and received in upward frames (C) at said central station, each of said downward (A) and said upward (C) frames comprising a predetermined number of consecutively numbered speech time slots (Tdl-TdM) of a common time slot length, each downward frame (A) further comprising a control time slot (TdO) including a frame synchronization code Fs as a part of said signals, said satellite stations (12) comprising time axis generating means (46) for generating time axes specific thereto, said time axis being for defining local time slots (D) in which signals are sent to be received at said central station (11) in said upward frames (C) from those of said satellite stations (12) which are carrying out the time division multiple access communication, characterised in that said central station (11) comprises: first central station means (25) for checking whether or not more than a preselected number of the speech time slots Tdl ~ TdM) are idle time slots in each of said downward and said upward frames and for assigning one of said idle time slots in each one of said downward and said upward frames to one of said satellite stations as an adjustment time slot for use in adjusting the time axis apecific to said one of the satellite stations; and second central station means (17,18) coupled to said first central station means (25) for transmitting a number code in said control time slot, said number code being representative of the number given to said adjustment time slot.
Claim 2
Dependent Claim
292 words
A time axis adjusting system for use in a radio communication network in which time division multiple access communication is carried out between a central station (11) and a plurality of satellite stations (12) by the use of signals sent in downward frames (A) and received in upward frames (C) at said central station, each of said downward (A) and said upward (C) frames comprising a predetermined number of consecutively numbered speech time slots (Tdl-TdM) of a common time slot length, each downward frame (A) further comprising a control time slot (TdO) including a frame synchronization code Fs as a part of said signals, said satellite stations (12) comprising time axis generating means (46) for generating time axes specific thereto, said time axis being for defining local time slots (D) in which signals are sent to be received at said central station (11) in said upward frames (C) from those of said satellite stations (12) which are carrying out the time division multiple access communication, characterised in that said central station (11) comprises: first central station means (25) for checking whether or not more than a preselected number of the speech time slots Tdl ~ TdM) are idle time slots in each of said downward and said upward frames and for assigning one of said idle time slots in each one of said downward and said upward frames to one of said satellite stations as an adjustment time slot for use in adjusting the time axis apecific to said one of the satellite stations; and second central station means (17,18) coupled to said first central station means (25) for transmitting a number code in said control time slot, said number code being representative of the number given to said adjustment time slot.
Claim 3
Dependent Claim
193 words
A time axis adjusting system as claimed in claim 1, characterised in that said central station (11) receives each upward frame (C) with a prescribed frame delay after sending each downward frame, each satellite station (12) comprises first satellite station means (41) for receiving said frame synchronization code and said number code, and the time axis generating means (46) of said each satellite station comprises: second satellite station means coupled to said first satellite station means for generating an adjustable time axis with an adjustable delay relative to the frame synchronization code received by said first satellite station means, said adjustable time axis defining adjustable time slots corresponding to the speech time slots of the upward frame; and third satellite station means coupled to said second satellite station means for sending a burst in one of said adjustable time slot that is specified by the number code received by said first satellite station means, said burst appearing with a prescribed burst delay relative to a leading edge of said one of the adjustable time slots to represent said adjustable delay and having a duration which is shorter than said common time slot length.
Claim 4
Dependent Claim
98 words
A time axis adjusting system as claimed in claim 2, characterised in that said central station (11) further comprises: third central station means for receiving said burst; fourth central station means for comparing said adjustable delay with said prescribed frame delay to produce an error signal indicative of a difference between the adjustable time axis and the time axis specific to said one of the satellite stations; and fifth central station means for sending said error signal in the adjustment time slot of the downward frame next following the downward frame in which said number code is sent.
Claim 5
Dependent Claim
67 words
A time axis adjusting system as claimed in claim 3, characterised in that the time axis generating means of each satellite station further comprises: fourth satellite station means for receiving said error signal; and fifth satellite station means coupled to said second and said fourth satellite station means for adjusting said adjustable time axis with reference to the error signal received by said fourth satellite station means.
References Cited (Backward Citations)
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