Forward and reverse link channels dynamic processing gain

• US 7,058,400 B2
• Filed: 06/14/2002
• Issued: 06/06/2006
• Est. Priority Date: 06/14/2002
• Status: Expired due to Fees

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Brooks, Frank P.
• Primary Examiner(s): NGUYEN, DUC MINH
• Application Number:
  US10/172,677
• Publication Number:
  US 20030232621A1
• Time in Patent Office: 1,453 Days
• Field of Search: 455423-424, 455/425, 455/522, 455/67.11, 455/67.14, 455/67.16, 455 68- 69, 4551151-1154, 4552261-2264, 370/333
• US Class Current: 455/424
• CPC Class Codes: H04W 24/00 Supervisory, monitoring or testing arrangements
• CPC Class Codes: H04W 28/22 Negotiating communication rate
• CPC Class Codes: H04W 76/10 Connection setup
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A method and apparatus for dynamically controlling forward and reverse link channel processing gain to minimize dropped connections and improve the reliability of hard handoffs is disclosed. The transmission bit stream of a forward or reverse link channel is allowed to become dynamic under controlled conditions in such a way as to take advantage of the inherit strengths that the concept of processing gain provides and thereby improve the probability of establishing and maintaining a forward or reverse link traffic channel. Dropped connections due to reverse link fades and dropped connections during call origination are minimized by allowing a MS to transmit reverse traffic channel data using dynamically adjustable data rates to increase the processing gain and the effective transmit power level. In addition, dropped connections during hard handoffs are minimized by using a special code channel and dynamically adjustable data rates to evaluate the proposed new link.

Claims

1. In a system comprising a network of base stations (BSs) and a mobile station (MS) for establishing a connection and maintaining one or more communication channels between them, a method for minimizing dropped connections between the MS and one of the BSs, comprising:

determining a frame error rate (FER) of a communication channel being maintained between the MS and the BS, the communication channel being a reverse traffic channel;

increasing a processing gain of the communication channel by decreasing a data rate of the communication channel if the FER is within an unacceptable range; and

during call origination,

initially transmitting the reverse traffic channel at a standby data rate lower than a voice data rate, and

incrementally increasing the standby data rate if the FER is within an acceptable range until the standby data rate is increased to the voice data rate.

2. The method as recited in claim 1, wherein the standby rate is initially selected to be lower than a MS access channel data rate.

3. The method as recited in claim 1, further comprising:

maintaining a call drop timer that starts when the reverse traffic channel is first transmitted at the standby data rate; and

dropping the connection if the call drop timer expires before the standby data rate is increased to the voice data rate.

4. In a system comprising a network of base stations (BSs) and a mobile station (MS) for establishing a connection and maintaining one or more communication channels between them, the MS having a current connection with a first BS and a proposed new connection to a second BS is being evaluated for a hard handoff, a method for evaluating a quality of the connection between the MS and the second BS, comprising:

assigning code channels as forward and reverse link evaluation channels for performing an active characterization of the connection;

temporarily dropping the connection between the MS and the first BS;

establishing a temporary connection between the MS and the second BS;

transmitting and receiving a known number progression across the forward and reverse link evaluation channels for each data rate in a sequence of data rates;

determining a frame error rate (FER) for each forward and reverse link evaluation channel at each data rate;

dropping the temporary connection between the MS and the second BS;

reestablishing the connection between the MS and the first BS; and

determining whether the proposed new connection should be used in the hard handoff based on the FER for each forward and reverse link evaluation channel at each data rate over the temporary connection.

5. A mobile station (MS) for communicating with a base station (BS) in a network of BSs via forward and reverse link channels, the BS for determining a frame error rate (FER) of the reverse link channel to assist in minimizing the chance of a dropped connection, the MS comprising:

a MS processor programmed for

receiving an indication of the FER of the reverse link channel, the reverse link channel being a reverse traffic channel,

increasing a processing gain of the reverse link channel if the indication of the FER shows that the FER is within an unacceptable range,

increasing the processing gain of the reverse link channel by decreasing a data rate of the reverse link channel, and

during call origination,

initially transmitting the reverse traffic channel at a standby data rate lower than a voice data rate, and

incrementally increasing the standby data rate if the indication of the FER shows that the FER is within an acceptable range, until the standby data rate is increased to the voice data rate.

6. The MS as recited in claim 5, wherein the standby rate is initially selected to be lower than a MS access channel data rate.

7. The MS as recited in claim 5, the MS processor further programmed for:

maintaining a call drop timer that starts when the reverse traffic channel is first transmitted at the standby data rate; and

dropping the connection if the call drop timer expires before the standby data rate is increased to the voice data rate.

8. A mobile station (MS) for establishing a connection with a base station (BS), communicating with the BS via forward and reverse link channels, and evaluating a quality of the connection, the MS having a current connection with a first BS and a proposed new connection to a second BS is being evaluated for a hard handoff, the MS comprising:

a MS processor programmed for

establishing reverse and forward link evaluation channels for performing an active characterization of the connection;

temporarily dropping the connection between the MS and the first BS;

establishing a temporary connection between the MS and the second BS;

transmitting a first known number progression across the reverse link evaluation channel and receiving a second known number progression across the forward link evaluation channel for each data rate in a sequence of data rates;

determining a frame error rate (FER) for the forward link evaluation channel at each data rate;

dropping the temporary connection between the MS and the second BS;

reestablishing the connection between the MS and the first BS; and

determining whether the proposed new connection should be used in the hard handoff based on the FER for the reverse link evaluation channel at each data rate over the temporary connection.

9. A network of base stations (BSs) for establishing a connection with a mobile station (MS), communicating with the MS via forward and reverse link channels, and evaluating a quality of the connection, the MS having a current connection with a first BS in the network and a proposed new connection to a second BS in the network is being evaluated for a hard handoff, the network comprising:

a network processor programmed for

establishing forward and reverse link evaluation channels for performing an active characterization of the connection;

temporarily dropping the connection between the MS and the first BS;

establishing a temporary connection between the MS and the second BS;

transmitting a first known number progression across the forward link evaluation channel and receiving a second known number progression across the reverse link evaluation channel for each data rate in a sequence of data rates;

determining a frame error rate (FER) for the reverse link evaluation channel at each data rate;

dropping the temporary connection between the MS and the second BS;

reestablishing the connection between the MS and the first BS; and

determining whether the proposed new connection should be used in the hard handoff based on the FER for the forward link evaluation channel at each data rate over the temporary connection.