Mobile station using synchronization word order information for improved channel acquisition

• US 6,256,304 B1
• Filed: 03/31/1998
• Issued: 07/03/2001
• Est. Priority Date: 03/31/1998
• Status: Expired due to Fees

• Current Assignee: Nokia Mobile Phones UK Limited (Nokia Corporation)
• Original Assignee: Nokia Mobile Phones UK Limited (Nokia Corporation)
• Inventors: Vayrynen, Mika
• Primary Examiner(s): Ton, Dang
• Assistant Examiner(s): TON, ANTHONY T
• Application Number:
  US09/052,658
• Time in Patent Office: 1,190 Days
• Field of Search: 370/350, 370/277, 370/347, 370/514, 370/345, 370/336, 370/330, 375/365, 375/367, 375/354, 375/368, 455/434, 455/343, 455/455, 455/525, 455/502, 714/704, 714/774
• US Class Current: 370/350
• CPC Class Codes: H04J 3/0605 Special codes used as synchronising signal

Abstract

A method is disclosed for operating a mobile station (10). The method includes a first step of receiving a message from a base station (30), the message being descriptive of an assigned forward digital channel and including an information element that specifies an order of occurrence of time slot synchronizing word sequences within a frame. A next step receives a forward channel from the base station, the forward channel being transmitted to contain repeating frames each having N time slots, individual ones of the time slots including a synchronization word. A further step correlates the received forward channel in accordance with the received information element so as to obtain a plurality of frame synchronization indications within one frame, thereby decreasing the frame synchronization time.

Claims

1. A method for operating a wireless terminal, comprising the steps of:

receiving a message from a base station, the message being descriptive of an assigned forward digital channel and including an information element that specifies an order of occurrence of time slot synchronization words within a frame;

receiving a forward digital channel signal from the base station, the forward digital channel signal being transmitted to contain repeating frames each comprising N time slots, individual ones of the time slots including a synchronization word such that there are N synchronizing words within a frame; and

correlating the received forward digital channel signal in accordance with the received information element so as to obtain a plurality of frame synchronization indications within one frame.

2. A method as in claim 1, wherein there are M possible different sequences of the synchronizing words, and where M>

N.

3. A method as in claim 2, wherein M=8 and N=6.

4. A method as in claim 1, wherein the first N/2 of the time slots are transmitted to have a same sequence of N/2 synchronization words whether the channel is a half-rate channel or a full-rate channel, and wherein the second N/2 of the time slots are transmitted to have a variable sequence of synchronization words depending on whether half data rate or full data rate wireless terminals are assigned to the frame.

5. A method as in claim 1, wherein the message is a Digital Traffic Channel Designation message for assigning the wireless terminal to a digital traffic channel.

6. A method as in claim 1, wherein the message is a Digital Traffic Channel Handoff message for handing off the wireless terminal from a current digital traffic channel to a different digital traffic channel.

7. A mobile station, comprising:

a receiver and demodulator for receiving and demodulating a forward digital channel signal from a base station, the forward digital channel signal being transmitted to contain repeating frames each comprising N time slots, individual ones of the time slots including a synchronization word such that there are N synchronizing words within a frame, said receiver and demodulator further receiving and demodulating a message from the base station, the message being descriptive of an assigned forward digital channel and including an information element that specifies an order of occurrence of time slot synchronization words within a frame;

a memory storing a plurality of predetermined synchronization word sequences and said received information element;

a correlator for correlating the received forward digital channel signal in accordance with the stored received information element and at least some of the plurality of predetermined synchronization word sequences so as to obtain a plurality of frame synchronization indications within one frame; and

a controller for synchronizing to a desired time slot of the forward digital channel using the plurality of frame synchronization indications.

8. A mobile station as in claim 7, wherein there are M possible different sequences of the synchronizing words, and where M>

N.

9. A mobile station as in claim 8, wherein M=8 and N=6.

10. A mobile station as in claim 7, wherein the first N/2 of the time slots are transmitted to have a same sequence of N/2 synchronization words whether the channel is a half-rate channel or a full-rate channel, and wherein the second N/2 of the time slots are transmitted to have a variable sequence of synchronization words depending on whether half data rate or full data rate mobile stations are assigned to the frame.

11. A mobile station as in claim 7, wherein the message is a Digital Traffic Channel Designation message for assigning the mobile station to a digital traffic channel.

12. A mobile station as in claim 7, wherein the message is a Digital Traffic Channel Handoff message for handing off the mobile station from a current digital traffic channel to a different digital traffic channel.

13. A method for operating a mobile station, comprising the steps of:

storing M time slot synchronization word sequences in a memory of the mobile station;

receiving a message from of a base station, the message being one of a Digital Traffic Channel Designation message for assigning the mobile station to a digital traffic channel or a Digital Traffic Channel Handoff message for handing off the mobile station from a current digital traffic channel to a different digital traffic channel, the message including a Synchronization Word Structure information element that specifies an order of occurrence of time slot synchronizing word sequences within a frame;

storing the received Synchronization Word Structure information in the memory of the mobile station;

receiving a Digital Traffic Channel signal that is transmitted by the base station to contain repeating frames each comprising N time slots, where M>

N, individual ones of the time slots including a synchronizing word;

correlating the received Digital Traffic Channel signal in accordance with the stored time slot synchronization word sequences and the stored Synchronization Word Structure information so as to obtain a plurality of frame synchronization indications within one frame; and

synchronizing the mobile station to at least one assigned time slot of the Digital Traffic Channel in cooperation with the plurality of frame synchronization indications.

14. A method as in claim 13, wherein M=8 and N=6.

15. A method as in claim 13, wherein the first N/2 of the time slots are transmitted to have a same sequence of N/2 synchronization words whether the channel is a half-rate channel or a full-rate channel, and wherein the second N/2 of the time slots are transmitted to have a variable sequence of synchronization words depending on whether half data rate or full data rate mobile stations are assigned to the frame.