Wireless private branch exchange (WPBX) and communicating between mobile units and base stations

• US 20020160806A1
• Filed: 02/20/2002
• Published: 10/31/2002
• Est. Priority Date: 04/07/2000
• Status: Active Grant

• Current Assignee: Commil USA LLC (Commil)
• Original Assignee: Commil, Ltd.
• Inventors: Barak, Haim, Arazi, Nitzan, Soffer, Yaron
• Granted Patent: US 7,231,212 B2
• Time in Patent Office: Days
• US Class Current: 455/555
• CPC Class Codes: H04M 1/724 User interfaces specially adapted for cordless or mobile telephones
• CPC Class Codes: H04M 1/725 Cordless telephones user interfaces specially adapted therefor H04M1/724
• CPC Class Codes: H04M 1/733 with a plurality of base stations connected to a plurality of lines for selection in cordless PBX H04W84/16
• CPC Class Codes: H04M 2250/02 including a Bluetooth interface
• CPC Class Codes: H04W 36/0033 with transfer of context information
• CPC Class Codes: H04W 36/00835 Determination of neighbour cell lists
• CPC Class Codes: H04W 36/08 Reselecting an access point
• CPC Class Codes: H04W 56/00 Synchronisation arrangements
• CPC Class Codes: H04W 76/00 Connection management
• CPC Class Codes: H04W 8/005 Discovery of network devices, e.g. terminals
• CPC Class Codes: H04W 84/105 PBS [Private Base Station] network H04W84/12 - H04W84/16 take precedence
• CPC Class Codes: H04W 84/16 WPBX [Wireless Private Branch Exchange]
• CPC Class Codes: H04W 88/02 Terminal devices

Abstract

Methods to create a cellular-like communication system, such as a Wireless Private Branch Exchange (WPBX), which includes mobile devices such as standard cordless phones (handsets), particularly, mobile devices utilizing the Bluetooth short-range wireless communication protocol. The methods provide seamless and reliable handoff of sessions between Base Stations while the mobile device is moving between picocells, by implementing a high-level of synchronization between the Base Stations and the Switch. Base Stations of picocells having small coverage areas communicate with the handsets. The communication protocol is divided into a low-level protocol performed by the Base Stations and a high-level protocol performed by the Switch connected to all the Base Stations. The methods support mobile computing or telephony devices and communication protocols, which are not specified to handle handoffs of sessions while moving between Base Stations coverage areas in a data, voice or telephony wireless network.

Claims

1. In a wireless communication system comprising at least two Base Stations, at least one Switch in communication with the Base Stations, and at least one mobile unit, a method of handing off the mobile unit from a Base Station communicating with the mobile unit and a neighboring Base Station, comprising:

smoothing a plurality of signals received from a handset by a plurality of Base Stations;

comparing the signals with one another; and

selecting a Base Station for handoff based on signal quality.

2. Method, according to claim 1, wherein:

the signals are compared by computing an average signal quality received from a given Base Station over a time interval encompassing subsequent signals from the given Base Station.

3. Method, according to claim 1, further comprising:

comparing the signals only during times in which the signal was received by more than one Base Station.

4. Method, according to claim 1, wherein the signal quality is based on a measurement selected from the group consisting of energy level, signal-to-noise ratio (SNR), packet loss ratio, and bit error rate (BER).

5. Method, according to claim 1, wherein:

the Base Stations communicate with the mobile units in hops;

the method further comprising;

prior to comparing the signals, aligning in time the measurements of the same hops.

6. Method, according to claim 5, wherein:

the measurements are averaged over a number (X) of hops

7. Method, according to claim 1, wherein the mobile unit is a device selected from the group consisting of:

telephone handset, standard cordless telephone handset, cellular telephone handset, personal data device, personal digital assistant (PDA), computer, laptop computer, e-mail server, a device utilizing point-to-point protocol (PPP) to the Internet via a central remote access server, a headset, a personal server, a wearable computer, a wireless camera, and a mobile music player.

8. Method, according to claim 1, further comprising:

providing communication links between the Base Stations, wherein the communication links between the Base Stations are selected from the group consisting of RF links and land lines; and

transferring connection status information and synchronization information between the Base Stations over the communications links.

9. Method, according to claim 1, wherein:

the Base Stations and the Switch are connected via a wired or wireless local area network (LAN).

10. Method, according to claim 1, wherein:

the wireless communication system comprises a wireless private branch exchange (WPBX) handling calls from mobile units comprising handsets.

11. In a wireless communication system comprising at least two Base Stations and at least one Switch in communication with the Base Stations, a method of performing handoff of a session from a Base Station connected with a mobile unit to a neighboring Base Station, wherein an instance of a low-level communications protocol is running at the Base Station connected with the mobile unit, comprising:

at the Switch, determining when to perform handoff to a selected one of the neighboring Base Stations;

at the selected one of the neighboring Base Stations, creating a copy of the low-level communications protocol, including at least a synchronized time of day (TOD) parameter;

from the Switch, sending a command to stop communication with the mobile unit at a specified TOD to the Base Station connected with the mobile unit and sending a command to start communication with the mobile unit at the specified TOD to the selected one of the neighboring Base Stations; and

updating session status tables in the Switch and in the Base Stations.

12. Method, according to claim 11, wherein:

the session is selected from the group consisting of phone call and data link.

13. Method, according to claim 11, wherein:

the low-level communications protocol comprises procedures selected from the group consisting of control and modulation of RF signals transmitted to the mobile unit by the Base Station, frequency hopping, error correction, accurate time synchronization, device address, rough Time Of Day (TOD), voice channel allocation, forward error correction parameters, encryption keys, authentication keys, voice coding, device addressing, address of a parked mobile unit, definition of an asynchronous data link, and data FIFOs.

14. Method, according to claim 11, wherein:

the mobile unit is equipped with a short-range wireless communication transmitter/receiver.

15. Method, according to claim 11, wherein the mobile unit is a device selected from the group consisting of:

telephone handset, standard cordless telephone handset, cellular telephone handset, personal data device, personal digital assistant (PDA), computer, laptop computer, e-mail server, a device utilizing point-to-point protocol (PPP) to the Internet via a central remote access server, a headset, a personal server, a wearable computer, a wireless camera, and a mobile music player.

16. Method, according to claim 11, further comprising:

providing communication links between the Base Stations, wherein the communication links between the Base Stations are selected from the group consisting of RF links and land lines; and

transferring connection status information and synchronization information between the Base Stations over the communications links.

17. Method, according to claim 11, wherein:

the Base Stations and the Switch are connected via a wired or wireless local area network (LAN).

18. Method, according to claim 11, wherein:

the wireless communication system comprises a wireless private branch exchange (WPBX) handling calls from mobile units comprising handsets.