Method for sequential data transmission

• US 5,367,524 A
• Filed: 05/17/1993
• Issued: 11/22/1994
• Est. Priority Date: 08/05/1991
• Status: Expired due to Fees

• Current Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Rideout, Kenneth E. Jr., Mills, Donald C.
• Primary Examiner(s): Olms, Douglas W.
• Assistant Examiner(s): Jung, Min
• Application Number:
  US08/062,032
• Time in Patent Office: 554 Days
• Field of Search: 370/95.1, 370/95.3, 370/100.1, 370/104.1, 342/356, 342/357
• US Class Current: 370/324
• CPC Class Codes: H04B 7/2693 Centralised synchronisation, i.e. using external universal time reference, e.g. by using a global positioning system [GPS] or by distributing time reference over the wireline network
• CPC Class Codes: H04J 3/0644 External master-clock
• CPC Class Codes: H04J 3/0647 Synchronisation among TDM nodes

Abstract

Sequential data transmission by a plurality of communication units may be achieved in a communication system by using an accurate external clock and transmitting at predetermined time intervals or time slots. By using a GPS clock signal as the external clock, a communication system may determine a cycle time and duration of time slots such that each communication unit is allocated a time slot for data transmission. This approach eliminates the need for polling of communication units and substantially reduces data congestion on control channels of the communication system.

Claims

1. In a wireless time division multiplexing (TDM) communication system that comprises at least two communication units and at least one TDM communication resource that is divided into at least two time slots, wherein each of the at least two communication units includes a global positioning system (GPS) receiver, and wherein a first communication unit of the at least two communication units is allocated a first time slot of the at least two time slots and a second communication unit of the at least two communication units is allocated a second time slot of the at least two time slots, a method for sequentially transmitting data by the at least two communication units, the method comprises the steps of:

a) synchronizing, via the GPS receiver, the at least two communication units to a clock signal that is produced by a global positioning system;

b) determining, by the first communication unit when the first time slot occurs within the TDM communication resource based on the clock signal;

c) determining, by the second communication unit when the second time slot occurs within the TDM communication resource based on the clock signal; and

d) transmitting, by the first communication unit and the second communication unit, data during the first time slot and the second time slot, respectively.

2. The method of claim 1 further comprises allocating at least one predetermined time slot as a priority data time slot.

3. The method of claim 1 further comprises maintaining a database to record which of the predetermined number of time slots each of the at least two communication units is allocated to.

4. The method of claim 3 further comprises deleting the allocation of at least one predetermined time slot to a communication unit when that communication unit becomes inactive.

5. In a wireless communication system that comprises a plurality of communication units, wherein each of the plurality of communication units includes a global positioning system receiver, wherein a global positioning system provides a clock signal, and wherein the plurality of communication units sequentially transmits data to a target during its allocated predetermined time slot of a selected cycle time, a method for a communication unit of the plurality of communication units to transmits its data, the method comprises the steps of:

a) monitoring the clock signal when the clock signal is available;

b) determining when its allocated predetermined time slot is active based on the clock signal;

c) transmitting data to the target when the communication units allocated predetermined time slot is active.

6. In the method of claim 5, step (a) further comprises using an internal clock to maintain synchronization when the clock signal is not available.

7. In the method of claim 6, step (a) further comprises synchronizing the internal clock with the clock signal when the clock signal is available.

8. The method of claim 5 further comprises enabling a transmitter of the communication unit prior to when its allocated predetermined time slot is active such that the transmitter is ready to transmit when the allocated predetermined time slot is active.

9. The method of claim 5 further comprises transmitting priority data during a priority time slot when a priority condition arises.