Transmission link supervision in radiocommunication systems
First Claim
1. A digital cellular communications system comprising:
- a switching unit including a speech code for coding downlink speech signals and decoding uplink speech signals that are respectively transmitted to and received from a base station via a transmission link;
wherein the transmission link conveys encoded downlink and uplink speech and control data in the form of respective downlink and uplink blocks;
wherein the base station operates to relay an encoded downlink speech signal received from the switching unit to a mobile station by transmission on a radio channel and to relay to the switching unit an encoded uplink speech signal received from the mobile station by transmission on the transmission link; and
means for marking a monitoring interval if a predetermined number of one of downlink and uplink blocks is conveyed erroneously over said transmission link during said monitoring interval and for reporting said transmission link as having poor quality if a predetermined number of monitoring intervals are marked within a predetermined time period.
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Accused Products
Abstract
A digital cellular communications system has a bidirectional transmission link for conveying encoded speech and control data in the form of blocks, a switching unit coupled to a first end of the transmission link, and a base station coupled to a second end of the transmission link. The switching unit includes a speech encoder for encoding speech signals, an error detection code generator for generating an error detection code from the encoded speech signal, and a formatter, coupled to the error detection code generator, for producing a formatted block to be transmitted on the transmission link, the formatted block having a header, the encoded speech data, and the error detection code. The base station has a transmission link error detector for signalling the existence of an error in a received block in response to the received block containing an error. Similarly, the switching unit has a transmission link error detector for signalling the existence of an erroneously received block which has been transmitted in the uplink direction. The number of errors is monitored by a transmission link supervisor which reports if the errors indicate that the quality of the transmission link has degraded beyond a predetermined threshold.
73 Citations
29 Claims
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1. A digital cellular communications system comprising:
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a switching unit including a speech code for coding downlink speech signals and decoding uplink speech signals that are respectively transmitted to and received from a base station via a transmission link; wherein the transmission link conveys encoded downlink and uplink speech and control data in the form of respective downlink and uplink blocks; wherein the base station operates to relay an encoded downlink speech signal received from the switching unit to a mobile station by transmission on a radio channel and to relay to the switching unit an encoded uplink speech signal received from the mobile station by transmission on the transmission link; and means for marking a monitoring interval if a predetermined number of one of downlink and uplink blocks is conveyed erroneously over said transmission link during said monitoring interval and for reporting said transmission link as having poor quality if a predetermined number of monitoring intervals are marked within a predetermined time period. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A digital cellular communications system comprising:
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a bidirectional transmission link for conveying encoded speech and control data in a block format; a switching unit coupled to a first end of the transmission link, the switching unit including; a speech encoder for encoding speech signals; means for generating an error detection code from the encoded speech signal; and formatting means, coupled to the generating means, for producing a formatted downlink block to be transmitted on the transmission link, the formatted downlink block having a header, the encoded speech data, and the error detection code; a base station coupled to a second end of the transmission link, the base station including link error detecting means for signalling existence of an error in a received downlink block in response to the received downlink block containing an error; first means for receiving said signalled error existence from said base station and generating an error signal if a first rate of erroneously received downlink blocks exceeds a first threshold; and second means for filtering an output of said first means by comparing a second rate at which said error signals are generated to a second threshold to distinguish between faulty and normal behavior of said transmission link. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20)
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21. A method for supervising a data transmission link comprising the steps of:
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counting a number of erroneously received blocks of data which have been transmitted through said data transmission link over a predetermined period of time; determining if said number exceeds a first threshold; selectively categorizing said period of time as a bad time period based upon said determination; storing said categorization of said period of time; evaluating a plurality of recent categorizations to determine if a number of bad time periods exceeds a second threshold; and selectively reporting that said data transmission link has insufficient quality based upon a result of said step of evaluating. - View Dependent Claims (22, 23, 24, 25)
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26. A method for handling a connection between a switching unit and a base station using one of a plurality of transmission links comprising the steps of:
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monitoring, for each of said plurality of transmission links, a number of erroneously received blocks over a predetermined time interval; selectively marking time intervals based upon a result of said monitoring step; distinguishing between faulty and normal behavior of each of said plurality of transmission links based upon a time distribution of said marked time intervals; selecting as said one of said plurality of data transmission links, a transmission link which has not been identified as faulty for handling said connection; and setting up said connection between said switching unit and said base station using said selected one of said data transmission links. - View Dependent Claims (27, 28, 29)
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Specification