Autonomous Timing Adjustment In A Communication Network
A method and apparatus for timing adjustment in a communication network. In a mobile network, one or more mobile stations (UEs) communication with a common base station (BS) for access to a core network. To align multiple uplink signals and reduce interference, a reference OTL is broadcast from the BS and received at the one or more UEs, the ROTL representing a real or theoretical maximum OTL (one-way trip latency). A universal time reference is then broadcast, often with other data, from the BS and is received by the one or more UEs. Each UE, if it is able, calculates its own OTL and uses that to calculate an δOTL representing an uplink transmission delay. In some cases, an δOTL′ may be calculated representing an uplink transmission delay that takes into account motion of the UE, if any. In some implementations, timing adjustments may be calculated by the BS and sent to individual UEs if necessary.
1 . A method for timing adjustment for a wireless communication network, comprising:
receiving in an UE (user equipment) an ROTL (reference one-way trip latency);
receiving in the UE an UTR (universal time reference);
calculating by the UE an OTL (one-way trip latency); and
calculating by the UE a transmission time adjustment.
2 . The method according to claim 1 , further comprising sending a transmission from the UE delayed by the calculated transmission time adjustment.
3 . The method according to claim 1 , wherein the ROTL and the UTR are received from a base station of the communication network.
4 . The method according to claim 1 , further comprising sending a common time availability status notification from the UE.
5 . The method according to claim 4 , further comprising receiving a transmission time adjustment.
6 . The method according to claim 5 , further comprising sending a transmission from the UE delayed by the received transmission time adjustment.
7 . The method according to claim 1 , further comprising maintaining a record of calculated OTL values.
8 . The method according to claim 7 , further comprising estimating a rate of change of OTL as a function of a plurality of OTL values.
9 . The method according to claim 8 , further comprising calculating a motion-compensated transmission time adjustment.
10 . The method according to claim 1 , wherein the OTL value comprises an internal processing time for the UE.
11 . The method according to claim 1 , further comprising determining an ROTL.
12 . The method according to claim 11 , further comprising broadcasting the ROTL.
13 . The method according to claim 11 , wherein determining the ROTL is executed in a base station of the communication network and comprises determining the maximum OTL for any UE currently within range of the base station.
14 . The method according to claim 11 , further comprising broadcasting a universal time reference.
15 . The method according to claim 11 , further comprising:
receiving at a base station of the communication network a notification that a UE does not have access to a common time value;
calculating by the base station a timing adjustment value for the UE; and
transmitting the time adjustment value.
16 . A UE, comprising:
a processor;
a memory device accessible to the processor;
an OTL calculator configured to calculate an OTL for the UE;
a transmission time adjustment calculator configured to calculate a timing adjustment as a function of a received UTR, a received ROTL, and the calculated OTL.
17 . The UE of claim 16 , further comprising an OTL value table for recording calculated OTL values.
18 . The UE of claim 17 , further comprising an OTL rate of change estimator configured to estimate a rate of OTL change for the UE.
19 . The UE of claim 18 , further comprising a motion-compensated transmission time adjustment calculator configured to calculate a motion-compensated transmission time adjustment as a function of the timing adjustment and the estimated rate of OTL change.
20 . A UE comprising:
a processor; and
a memory device, the memory device comprising program instructions that when executed by the processor cause the UE to:
calculate an OTL (one-way trip latency); and
calculate a transmission time adjustment.