Method for determining and utilizing simulcast transmit times by master transceiver

• US 5,530,915 A
• Filed: 05/28/1993
• Issued: 06/25/1996
• Est. Priority Date: 02/26/1993
• Status: Expired due to Fees

• Current Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Grube, Gary W., Shaughnessy, Mark L., Ng, Richard
• Primary Examiner(s): Eisenzopf, Reinhard J.
• Assistant Examiner(s): TO, DORIS HA
• Application Number:
  US08/068,879
• Time in Patent Office: 1,124 Days
• Field of Search: 455/51.2, 455/51.1, 455/54.1, 455/54.2, 455/33.1, 455/67.1, 455/67.6, 455/69, 455/53.1, 455/18, 375/107, 375/109, 375/110, 375/356, 375/358, 375/359
• US Class Current: 455/503
• CPC Class Codes: H04B 17/20 of receivers
• CPC Class Codes: H04W 24/00 Supervisory, monitoring or testing arrangements
• CPC Class Codes: H04W 4/06 Selective distribution of broadcast services, e.g. multimedia broadcast multicast service [MBMS]; Services to user groups; One-way selective calling services
• CPC Class Codes: H04W 4/10 Push-to-Talk [PTT] or Push-On-Call services
• CPC Class Codes: H04W 76/45 for Push-to-Talk [PTT] or Push-to-Talk over cellular [PoC] services
• CPC Class Codes: H04W 84/08 Trunked mobile radio systems

Abstract

Determining transmit time of a received signal in a simulcast multi-site communication system begins when a communication unit transmits a message to one or more network receivers. The receivers transport the received signal with a time stamp to a master transceiver in the network via a digital communication network. The master transceiver then determines a launch time for transmission of a selected received signal, wherein the launch time is based on a previously executed procedure to determine the inbound and outbound delays in the simulcast multi-site communication system. Finally, the master transceiver transports the selected received signal with the launch time to other transceivers assigned to the call, wherein the transceivers transmit the selected received signal at the launch time.

Claims

1. In a simulcast communication system that includes a plurality of sites including at least two transceiver sites, a time reference, and a plurality of communication units, and wherein the plurality of sites are operably linked together by a non-star topology digital communication network, a method of determining simulcast delay times for the digital communication network, the method comprising the steps of:

a) receiving, by at least a first of the plurality of sites, an indication of a call assignment on the non-star topology digital communication network to produce a call assignment indicator, which call assignment indicator identifies a master site transceiver;

b) transporting, by the identified master transceiver site, a time stamp message on to the non-star topology digital communication network;

c) receiving, by other transceiver sites of the at least two transceiver sites, the time stamp message;

d) calculating, by each of the other transceiver sites, an outbound delay time, wherein the outbound delay time is based on the time stamp message and time when the time stamp message was received;

e) transporting, by each of the other transceiver sites, the outbound delay time and a transceiver time stamp message to the identified master transceiver site via the non-star topology digital communication network;

f) storing, by the identified master transceiver site, the outbound delay time for each of the other transceiver sites;

g) calculating, by the identified master transceiver site, an inbound delay time for each of the other transceiver sites, wherein the inbound delay time is based on the transceiver time stamp message and time when the transceiver time stamp message was received; and

h) storing, by the identified master transceiver site, the inbound delay time for each of the other transceiver sites.

2. The method of claim 1, wherein the simulcast communication system further comprises at least one receiver site having a receiver, the method further comprising the steps of:

i) receiving, by the identified master transceiver site, a receiver time stamp message from the at least one receiver site;

j) calculating, by the identified master transceiver site, an inbound delay time for the at least one receiver site, wherein the inbound delay time is based on the receiver time stamp message and time when the receiver time step message was received; and

k) storing, by the identified master transceiver site, the inbound delay time for the at least one receiver site.

3. In a simulcast communication system that includes a plurality of sites including at least two transceiver sites, a time reference, and a plurality of communication units, and wherein the plurality of sites are operably linked together by a non-star topology digital communication network, a method for a transceiver site of the at least two transceiver sites to determine simulcast delay times of the digital communication network, the method comprising the steps of:

a) receiving, from a master transceiver site identified by a call assignment, a time stamp message on the non-star topology digital communication network;

b) upon receiving the time stamp message, calculating, by the transceiver site, an outbound delay time, wherein the outbound delay time is based on the time stamp message and time when the time stamp message was received; and

c) transporting, by the transceiver site, the outbound delay time and a transceiver time stamp message to the master transceiver site via the non-star topology digital communication network, such that the master transceiver site calculates an inbound delay time for the transceiver site based on the transceiver time stamp message.

4. In a simulcast communication system that includes a plurality of sites including at least two transceiver sites, a time reference, and a plurality of communication units, wherein at least one of the plurality of sites is a receiver site that includes a receiver, and wherein the plurality of sites are operably linked together by a non-star topology digital communication network, a method of determining simulcast transmit times of received signals, the method comprising the steps of:

a) receiving, by a receiver site or a transceiver site, a signal from a communication unit to produce a received signal;

b) transporting, by the receiver site or the transceiver site, the received signal and a signal time stamp message to an assigned master transceiver site via the non-star topology digital communication network;

c) calculating, by the assigned master transceiver site, a wait period based on calculated inbound delay times for each receiver site and each transceiver site, wherein the assigned master transceiver site waits for a duration of the wait period to receive the received signal from another receiver site or transceiver site;

d) when the wait period expires, selecting when there is more than one received signal, by the assigned master transceiver site, the received signal to broadcast from among the more than one received signal to produce a selected received signal;

e) determining, by the assigned master transceiver site, a launch time based on stored outbound delay times of each transceiver site;

f) transporting, by the assigned master transceiver site via the non-star topology digital communication network, the selected received signal and the launch time to the other transceiver sites of the at least two transceiver sites; and

g) transmitting the selected received signal by each of the at least two transceiver sites at the launch time.

5. In the method of claim 4, the calculation of the wait period of step (c) further comprises calculating the wait period to be substantially equal to the stored inbound delay time of the receiver site or transceiver site having greatest stored inbound delay time.

6. In the method of claim 4, the determination of the launch time of step (e) further comprises determining the launch time to be substantially equal to the stored outbound delay time of the transceiver site of the at least two transceiver sites having greatest stored outbound delay time.