# US 5,710,772 A · TDMA radio communication system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,710,772 A - Document ID: US5710772A - Status: Granted - Kind: A - Application number: 08/470,622 - Filed: 1995-06-06 - Granted: 1998-01-20 - Earliest claimed: 1994-06-06 - Assignees: NEC Corporation - Inventors: Osamu Sato - Web page: https://patentgrep.com/patent/US5710772A ## CPC - H04B 17/309: Measuring or estimating channel quality parameters - H04W 36/0088: {Scheduling hand-off measurements} - Y02D 30/70: in wireless communication networks - H04B: TRANSMISSION - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) - Y02D: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE ## Abstract A mobile station sends a speech signal to a radio base station or, in the absence of speech signals, sends back a sync signal from the radio base station. The radio base station detects whether the signal received from the mobile station is a speech signal or the sync signal it sent. If a speech signal is received, it performs usual processing for speech signals or, if the sync signal is received, judges the line quality according to this sync signal. ## Claims ### Claim 1 A TDMA radio communication system whereby a radio base station and a mobile station transmit to and receive from each other digital speech signals over a radio line consisting of a plurality of time-division-multiplexed time slots, said mobile station comprising: extracting means for extracting a first sync signal from signals received from said radio base station; detecting means for detecting the presence or absence of transmit speech signals; and sending means for sending said first sync signal to said radio base station in the absence of said transmit speech signals, and sending said transmit speech signals to said radio base station in the presence of said transmit speech signals. ### Claim 2 (depends on 1) The TDMA radio communication system, as claimed in claim 1, wherein said mobile station further comprises: a microphone; and converting means for converting speech from said microphone into speech signals. ### Claim 3 (depends on 2) The TDMA radio communication system, as claimed in claim 2, wherein said transmit speech signals are said speech signals. ### Claim 4 (depends on 1) The TDMA radio communication system, as claimed in claim 1, wherein said sending means comprises: a switch responsive to a switch control signal from said detecting means for switching between said transmit speech signals and said first sync signal. ### Claim 5 (depends on 4) The TDMA radio communication system, as claimed in claim 4, wherein said sending means comprises: transmitting means for adding a second sync signal to the output signal of said switch and sending the augmented signal. ### Claim 6 (depends on 4) The TDMA radio communication system, as claimed in claim 4, wherein said mobile station comprises a memory for storing said first sync signal. ### Claim 7 (depends on 6) The TDMA radio communication system, as claimed in claim 6, wherein said memory is updated every time said first sync signal is received from said radio base station. ### Claim 8 A TDMA radio communication system whereby a radio base station and a mobile station transmit to and receive from each other digital speech signals over a radio line consisting of a plurality of time-division-multiplexed time slots, said radio base station comprising: transmitting means for transmitting a first sync signal; first receiving means for receiving said first sync signal returned from said mobile station; and judging means for judging the quality of said radio line according to said first sync signal. ### Claim 9 (depends on 8) The TDMA radio communication system, as claimed in claim 8, wherein said mobile station sends said first sync signal during silent periods. ### Claim 10 (depends on 8) The TDMA radio communication system, as claimed in claim 8, wherein said judging means calculates the bit error rate of said first sync signal, and judges said radio line quality according to said bit error rate. ### Claim 11 (depends on 8) The TDMA radio communication system, as claimed in claim 8, said radio base station further comprising: second receiving means for receiving a second sync signal from said mobile station, and detecting means for detecting the receive field intensity of said second sync signal. ### Claim 12 (depends on 11) The TDMA radio communication system, as claimed in claim 11, wherein said judging means judges said radio line quality according to the bit error rate of said first sync signal and the receive field intensity of said second sync signal. ### Claim 13 (depends on 8) The TDMA radio communication system, as claimed in claim 8, wherein said judging means judges said radio line quality according to said first sync signal and the bit error rate of said second sync signal from said mobile station. ### Claim 14 In a TDMA radio communication system whereby a radio base station and a mobile station transmit to and receive from each other digital speech signals over a radio line consisting of a plurality of time-division-multiplexed time slots, a method for controlling transmission from said mobile station comprising the steps of: detecting the presence or absence of transmit speech signals; and sending a sync signal received from said radio base station in the absence of said transmit speech signals and, in the presence of said transmit speech signals, sending said transmit speech signals. ### Claim 15 (depends on 14) The method claimed in claim 14, further comprising the steps of: storing in memory said sync signal received from said radio base station; and updating said memory every time said sync signal is received. ### Claim 16 In a TDMA radio communication system whereby a radio base station and a mobile station transmit to and receive from each other digital speech signals over a radio line consisting of a plurality of time-division-multiplexed time slots, a method for controlling transmission from said radio base station, comprising the steps of: receiving signals from said mobile station; judging whether or not said signals indicate a silent period, and judging, if they indicate a silent period, the line quality according to a first sync signal from said radio base station, contained in said signals or, if they do not indicate a silent period, processing speech signals contained in said signals. ### Claim 17 (depends on 16) The method claimed in claim 16, further comprising the steps of: judging the reception state of a second sync signal generated by said mobile station and contained in signals from said mobile station; and executing line control according to judgment on said first sync signal and judgment on said second sync signal.