SOFTER HANDOFF IN A BASE STATION EMPLOYING VIRTUAL CHANNEL ELEMENTS

• US 20020098842A1
• Filed: 10/14/1998
• Published: 07/25/2002
• Est. Priority Date: 10/14/1998
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: LEE, KUO-CHUN, ANTONIO, FRANKLIN, WEGRZYN, JAN K., DEHESH, HOUTAN, HAMDY, WALID
• Granted Patent: US 6,519,456 B2
• Time in Patent Office: Days
• US Class Current: 455/442
• CPC Class Codes: H04W 36/06 Reselecting a communication resource in the serving access point
• CPC Class Codes: H04W 36/18 for allowing seamless reselection, e.g. soft reselection
• CPC Class Codes: H04W 52/40 during macro-diversity or soft handoff

Abstract

A base station architecture splits modem functionality into modulator and demodulator entities, each configured to handle multiple telephone calls. A high-speed digital bus with associated routing elements connects multiple-channel (i.e., multiuser) modulator and demodulator elements. The modulator and demodulator elements may be physically separated, residing on different cards, and even different shelves, within the base station. During softer handoff between forward channels of the base station, multiple modulator elements use the address of a demodulator element in communication with a mobile subscriber unit. A base station controller broadcasts forward-link frames to all modulator elements. The multiple modulator elements simultaneously receive forward-link frames from the base station controller. The multiple modulator elements filter these forward-link frames and accept only those to be transmitted to the particular mobile subscriber unit in communication with the demodulator element.

Claims

1. In a wireless communication system including at least one base station and at least one base station controller, a method of performing softer handoff of forward-link communications with a mobile subscriber unit between first and second modulators associated, respectively, with first and second forward channels of a base station, the base station receiving reverse-link communications from the mobile subscriber unit on a reverse channel through a demodulator associated with the reverse channel, the method comprising the steps of:

assigning a voice address to the first modulator;

assigning the voice address to the second modulator; and

filtering a plurality of forward-link communications so that only the forward-link communications that include the voice address are accepted by the first and second modulators.

2. The method of claim 1, wherein the assigning step is performed by the demodulator.

3. The method of claim 1, further comprising the step of adding a virtual-channel-element internal signaling address to the voice address.

4. The method of claim 3, wherein the adding step is performed by the demodulator.

5. The method of claim 1, further comprising the step of sending the plurality of forward-link communications to the base station from a base station controller.

6. The method of claim 1, further comprising the step of sending the reverse-link communications from the demodulator to a base station controller.

7. The method of claim 1, further comprising the step of removing the voice address from the first modulator.

8. In a wireless communication system including at least one base station controller, a base station configured to perform softer handoff of forward-link communications with a mobile subscriber unit between first and second modulators associated, respectively, with first and second forward channels of the base station, the base station receiving reverse-link communications from the mobile subscriber unit on a reverse channel through a demodulator associated with the reverse channel, the base station comprising:

means for assigning a voice address to the first modulator;

means for assigning the voice address to the second modulator; and

means, coupled to the first and second modulators, for filtering a plurality of forward-link communications so that only the forward-link communications that include the voice address are accepted by the first and second modulators.

9. The base station of claim 8, wherein the demodulator is configured to assign the voice address.

10. The base station of claim 9, wherein the demodulator is configured to add a virtual-channel-element internal signaling address to the voice address.

11. The base station of claim 8, further comprising means for sending the plurality of forward-link communications to the base station from the at least one base station controller.

12. The base station of claim 8, further comprising means for sending the reverse-link communications to the at least one base station controller from the demodulator.

13. The base station of claim 8, further comprising means for removing the voice address from the first modulator.

15. The base station of claim 14, wherein the demodulator is further configured to add a virtual-channel-element internal signaling address to the voice address.

16. The base station of claim 14, wherein the at least one base station controller is configured to send a plurality of forward-link communications to the base station.

17. The base station of claim 14, wherein the demodulator is configured to send the reverse-link communications to the at least one base station controller.

18. The base station of claim 14, wherein the first and second modulators are configured to use the voice address upon receiving a request from the at least one base station controller.

19. The base station of claim 14, wherein the first and second modulators are configured to stop using the voice address upon receiving a request from the at least one base station controller.

14. In a wireless communication system including at least one base station controller, a base station configured to perform softer handoff of forward-link communications with a mobile subscriber unit between first and second forward channels of the base station, the base station receiving reverse-link communications from the mobile subscriber unit on a reverse channel, the base station comprising:

a demodulator associated with the reverse channel and configured to assign a voice address;

a first modulator associated with the first forward channel and configured to use the voice address assigned by the demodulator and to accept only forward-link voice communications that include the voice address; and

a second modulator associated with the second forward channel and configured to use the voice address and to accept only forward-link voice communications that include the voice address.