Systems and methods for fast terminal synchronization in a wireless communication system

• US 6,353,645 B1
• Filed: 11/22/2000
• Issued: 03/05/2002
• Est. Priority Date: 10/15/1998
• Status: Expired due to Term

• Current Assignee: Optis Wireless Technology, LLC (Brevet Capital)
• Original Assignee: Ericsson, Inc. (Telefonaktiebolaget LM Ericsson)
• Inventors: Solve, Torbjorn, Ranta, Mark
• Primary Examiner(s): CORRIELUS, JEAN B
• Application Number:
  US09/718,167
• Time in Patent Office: 468 Days
• Field of Search: 375/354, 375/365, 375/366, 375/368, 370/503, 370/509, 370/510, 370/513, 370/520, 455/522, 455/502, 455/574, 455/609
• US Class Current: 375/354
• CPC Class Codes: H04W 48/16 Discovering, processing access restriction or access information
• CPC Class Codes: H04W 48/20 Selecting an access point

Abstract

Methods and systems are provided for synchronization of a mobile terminal to a communication system which provide faster access to the communication system and reduced risk of non-productive battery power consumption. In particular, the methods and systems of the present invention test one candidate carrier from a list of candidate carriers and perform a power profile to obtain an indication of signal strength of the carrier. This signal measurement is then compared to a threshold criteria. If the criteria is satisfied, the mobile terminal attempts synchronization with that carrier and, if successful, establishes a connection with the communication system. If the criteria is not satisfied, another candidate carrier is selected and tested similarly. Furthermore, the methods and systems of the present invention provide for tiered searching for a valid carrier with each level providing an increased likelihood of finding a carrier while, potentially, requiring a greater amount of time to obtain synchronization. The methods and systems of the present invention also provide a hierarchical approach to searching when no carrier has been identified which reduces the rate of battery power consumption while the mobile terminal is attempting to synchronize with a communication system.

Claims

1. A method for initial synchronization of a mobile terminal with a communication system, the mobile terminal having a list of candidate carriers for the communication system, the method comprising the steps of:

selecting a first carrier from the list of candidate carriers, wherein the mobile terminal is not synchronized to the communication system;

generating a power profile of the first carrier before attempting to synchronize to the first carrier;

comparing the power profile of the first carrier to a first threshold criteria; and

then

synchronizing to the first carrier if the power profile of the first carrier satisfies the first threshold criteria.

2. A method according to claim 1 further comprising the steps of:

selecting a second carrier from the list of candidate carriers if the power profile of the first carrier does not satisfy the first threshold criteria;

generating a power profile of the second carrier before attempting to synchronize to the second carrier;

comparing the power profile of the second carrier to a second threshold criteria; and

then

synchronizing to the second carrier if the power profile of the second carrier satisfies the second threshold criteria.

3. A method according to claim 2 wherein the second threshold criteria is more lenient than the first threshold criteria.

4. A method according to claim 1 wherein the synchronizing step includes the steps of:

coarse synchronizing to the first carrier; and

then

fine synchronizing to the first carrier.

5. A method according to claim 4 wherein the synchronizing step includes the steps of:

reading data from the first carrier;

determining if the data is valid; and

then

repeating the selecting, generating, comparing and synchronizing steps if the data is not valid.

6. The method of claim 1 wherein the list of candidate carriers for the communication system comprises a list of candidate control channels for the communication system.

7. A synchronization system for initial synchronization with a communication system of a mobile terminal having a list of candidate carriers for the communication system, the synchronization system comprising:

means for selecting a first carrier from the list of candidate carriers, wherein the mobile terminal is not synchronized to the communication system;

means for generating a power profile of the first carrier before attempting to synchronize to the first carrier;

means for comparing the power profile of the first carrier to a first threshold criteria; and

means for synchronizing to the first carrier if the power profile of the first carrier satisfies the first threshold criteria.

8. The system of claim 7 wherein the list of candidate carriers for the communication system comprises a list of candidate control channels for the communication system.

9. A synchronization system for initial synchronization with a communication system of a mobile terminal having a list of candidate carriers for the communication system, the synchronization system comprising:

a transceiver configured to receive a selected carrier; and

a processor that selects a first carrier from the list of candidate carriers to be received by the transceiver, wherein the mobile terminal is not synchronized to the communication system, generates a power profile of the first carrier before attempting to synchronize to the first carrier, compares the power profile of the first carrier to a first threshold criteria, and synchronizes to the first carrier if the power profile of the first carrier satisfies the first threshold criteria.

10. The system of claim 9 wherein the list of candidate carriers for the communication system comprises a list of candidate control channels for the communication system.