Method of handoff control in an enterprise code division multiple access wireless system

• US 7,154,870 B2
• Filed: 08/05/2005
• Issued: 12/26/2006
• Est. Priority Date: 09/05/2000
• Status: Expired due to Fees

• Current Assignee: Cisco Systems, Inc.
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Joo, Ki Hyun, Hyun, Sang Kyoon, Rha, Peter S., Kang, Chol Su
• Primary Examiner(s): Phunkulh, Bob A.
• Application Number:
  US11/198,651
• Publication Number:
  US 20060034229A1
• Time in Patent Office: 508 Days
• Field of Search: None
• US Class Current: 370/334
• CPC Class Codes: H04W 36/14 Reselecting a network or an air interface
• CPC Class Codes: H04W 36/32 by location or mobility data, e.g. speed data
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management
• CPC Class Codes: H04W 80/00 Wireless network protocols or protocol adaptations to wireless operation

Abstract

A wireless office communication system including a wireless internet base station (WIBS) encompassing a base station controller (BSC), a mobile switch controller (MSC), and an ethernet interface module for coupling the wireless internet base station (WIBS) to an existing internet protocol (IP) based network. A wireless office communication system can also be based on the conventional architecture comprising the base station transceiver subsystem BTS, BSC, and MSC. The WIBS or BTS is attached to a number of antennas via different and identifiable delay elements for the purpose of determining the serving antennas of mobile communication units. A location determination logic enables the system to handle handoffs between a WIBS or BTS and the external public communication system in an optimum manner. Handling handoff requests in this manner prevents unnecessary ping-ponging of hand off and can also increase the percentage of successful handoff by frequency monitoring of the quality of the mobile communication units located in the handoff transition area, particularly to the public communication system.

Claims

1. A system for executing a handoff, comprising:

means for sending a plurality of hand off request signals associated with a communication session to a base station within an enterprise system, wherein one of the plurality of handoff request signals emanating from a pre-designated handoff transition region within the enterprise system is identified, whereby time delaying of the handoff request signals to the base station is performed, and wherein the time delaying of the handoff request signals includes dividing the handoff request signals into multiple request signals responsive to antenna units within the enterprise system; and

means for executing the communication session.

2. The system of claim 1, further comprising:

means for combining the divided delayed signals into a single request signal to be sent to the base station.

3. The system of claim 1, wherein a transmit distribution subsystem is provided to interact with a base transceiver station and the means for sending the handoff request signal.

4. The system of claim 1, wherein the means for time delaying the handoff request signals includes means for inserting time delays only in handoff request signals sent by mobile units within the enterprise system.

5. The system of claim 1, wherein the means for time delaying the handoff request signals includes the step of inserting time delays only in the handoff request signals sent to base stations within the enterprise communication system.

6. The system of claim 1, wherein a handoff request is denied if it is not within the transition region.

7. The system of claim 1, wherein if a mobile communication device is within the transition region, then handoff parameters are changed in order to enhance a successful execution of a handoff.

8. A system for managing a handoff between a mobile communication unit within a code division multiple access (CDMA) communication system and an external public cellular system, comprising:

means for receiving a plurality of handoff request signals, wherein a handoff region within the communication system is designated;

means for identifying an originating location of the handoff request signals by making delay measurements of each of the plurality of handoff request signals;

means for using location identification information to hand off each of the request signals; and

means for time delaying the handoff request signals to a base station, wherein time delaying of the handoff request signals includes dividing the handoff request signals into multiple request signals responsive to multiple extended antenna units within the enterprise system.

9. The system of claim 8, further comprising:

means for determining whether handoff request signals are emanating from the handoff region.

10. The system of claim 8, wherein if the handoff request signal emanates from the transition region, the mobile communication unit transmitting the handoff request signal is handed off to the external public cellular system.

11. The system of claim 8, wherein if the handoff request signal emanates from a location outside of the transition region, then the mobile communication unit transmitting the handoff request signal is handed off to a base station within the communication system.

12. An apparatus for optimizing handoff between an enterprise code division muitiple access (CDMA) communication system and a cellular communication system, comprising:

a mobile communication unit operable to send a plurality of hand off request signals to a base station within the enterprise system, wherein an identification is performed of which one of the plurality of handoff request signals emanates from a pre-designated handoff transition region within the enterprise system, whereby the identified handoff request signal is handed off to the cellular communication system, and wherein time delaying of the handoff request signals to the base station is executed, the handoff request signals being divided into multiple request signals responsive to antenna units within the enterprise system.

13. The apparatus of claim 12, wherein the divided delayed signals are combined into a single request signal to be communicated to the base station.

14. The apparatus of claim 12, wherein the mobile communication unit is coupled to a transmit distribution subsystem.

15. The apparatus of claim 14, wherein the transmit distribution subsystem includes a plurality of signal transmit delay elements coupled to a signal dividing unit.

16. The apparatus of claim 12, wherein time delays are only inserted in handoff request signals sent by mobile communication units in the enterprise system.

17. The apparatus of claim 12, wherein time delays are only inserted in the handoff request signals sent to base stations within the enterprise communication system.

18. The apparatus of claim 12, wherein the mobile communication unit is operable to send a handoff request signal comprising a pilot strength measurement message (PSMM) to a base station within the CDMA communication system.

19. The apparatus of claim 18, wherein locations of mobile communication units are determined by making delay measurements of each of the mobile communication units.

20. The apparatus of claim 18, wherein prior to a handoff being performed, a determination is made as to whether the handoff request signals meets an enterprise system criteria or a public cellular system handoff criteria.

21. The apparatus of claim 20, wherein if the handoff request signal meets the enterprise system and public cellular system handoff criteria, then the PSMM is sent to a target base station.

22. The apparatus of claim 12, wherein a handoff request is denied if it is not within the transition region.

23. The apparatus of claim 12, wherein if a mobile communication device is within the transition region, then handoff parameters are changed in order to enhance a successful execution of a handoff.