Time synchronized standby state to the GPRS medium access control protocol with applications to mobile satellite systems

• US 20060072520A1
• Filed: 03/22/2001
• Published: 04/06/2006
• Est. Priority Date: 03/23/2000
• Status: Abandoned Application

• Current Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Original Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Inventors: Farnum, Philip Talbot, Chitrapu, Prabhakar Rao, Stack, Robert Michael
• Application Number:
  US09/814,788
• Publication Number:
  US 20060072520A1
• Time in Patent Office: Days
• US Class Current: 370/337
• CPC Class Codes: H04B 7/2125 Synchronisation
• CPC Class Codes: H04B 7/2656 for structure of frame, burst

Abstract

Improved throughput is provided in a spacecraft TDMA cellular communications system by introducing a standby state, in addition to the idle and transfer states, of the medium access control (MAC) protocol, which controls the transfer of data over the radio interface between the network and the user terminals. The terrestrial locations include mobile user terminals and gateways which provide connections to the land line telephone system and/or the land packet data network i.e. Internet service provider. Each of the terrestrial terminals and gateways include a MAC to control the transmitting and receiving of data between the gateway and user terminals. Since packet data is bursty, multiple transitions occur between the idle and transfer states during data transfers. The new standby state maintains synchronization, reducing the transition time to the data transfer state by comparison with the transition time from an idle state where the network does not maintain user synchronization.

Claims

1. A method for operating a user terminal of a wireless TDMA packet data communication system including a network communication center and a plurality of gateways, said method comprising the steps of:

at said user terminal, operating in an idle state in which said user terminal is attached to a network so that the network is aware of the presence of the user terminal, but said user terminal is not in communication with a gateway;

at said user terminal, transitioning from said idle state to an active state in response to one of (a) said network and (b) said user terminal generating a signal indicating that data is to be transmitted, by use of common control channels of said data communication system, by transitioning control to one of said gateways;

in said active state of said user terminal, transferring said data between said user terminal and said gateway;

immediately following said transferring of said data, transitioning from said active state to a standby state, in which timing information, but not data, is exchanged between said user terminal and said gateway;

in response to generation of a further signal indicating that data is to be transmitted by (a) said user terminal and (b) said gateway, transitioning said user terminal from said standby state of operation to said active state of operation; and

in response to expiration of a preset period of time in which no signal indicating that data is to be transmitted is generated, transitioning said user terminal from said standby state to said idle state.

2. A method for operating a user terminal of a wireless TDMA packet data communication system, which communication system includes a plurality of user terminals and a network, in which the said user terminal can be in one of an idle state, a stand-by state and an active state, wherein:

said idle state is a state in which said user terminal is attached to a network in a communication sense so that the network is aware of the presence of said user terminal, but said user terminal is not in communication with said network;

said active state is a state in which said user terminal transfers data between said user terminal and said network; and

said standby state is a state in which timing information, but not user data, is exchanged between said user terminal and said network.

3. A method according to claim 2, wherein, in said standby state, said network sends timing adjustment messages to said user terminal.

4. A method for operating a user terminal of a wireless TDMA packet data communication system, said communication system including a plurality of user terminals and a network, in which the said user terminal is capable of being in one an idle state, an active state, and a standby state, and in which said user terminal transitions from said idle state to said active state in response to one of (a) said network and (b) said user terminal generating a signal indicating that data is to be transmitted, said transition being by use of common control channels of said data communication system.

5. A method for operating a user terminal of a wireless TDMA packet data communication system, said data communication system including a plurality of user terminals and a network, in which each said user terminal is capable of being in one an idle state, an active state, and a standby state, and in which each said user terminal transitions from said active state to said standby state immediately following data transfer, and in which timing information, but not data, is exchanged between said user terminal and said network in said standby state.

6. A method for operating a user terminal of a wireless TDMA packet data communication system including a plurality of user terminals and a network, in which each said user terminal is capable of being in one of an idle state, an active state, and a standby state, and in which each said user terminal transitions from said standby state to said active state in response to generation of a further signal indicating that data is to be transmitted by (a) said user terminal and (b) said network.

7. A method for operating a user terminal of a wireless TDMA packet data communication system, said communication system including a plurality of user terminals and a network, in which each said user terminal is capable of being in an idle state, an active state, and a standby state, and in which each said user terminal transitions from its standby state to its idle state in response to expiration of a preset period of time in which no signal indicating that data is to be transmitted is generated by said network and that one of said user terminals.

8. A method for operating a user terminal of a wireless TDMA packet data communication system, said communication system including a plurality of user terminals and a network, in which each said user terminal can be in one of an idle state, a stand-by state, and an active state, and where said network includes a Network Control Center, a plurality of Gateways, and one or more satellites which provide communication between the user terminals and said NCC and at least some of said Gateways.