Shared base stations for voice and data cellular telecommunications and method

• US 5,721,762 A
• Filed: 12/27/1995
• Issued: 02/24/1998
• Est. Priority Date: 12/01/1993
• Status: Expired due to Term

• Current Assignee: Sharp Laboratories of America Incorporated (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.), Sharp Microelectronics Technology, Inc.
• Inventors: Sood, Prem
• Primary Examiner(s): Coles, Sr., Edward L.
• Assistant Examiner(s): NGUYEN, ANH-VINH THI
• Application Number:
  US08/579,452
• Time in Patent Office: 790 Days
• Field of Search: 379/59, 379/58, 379/60, 379/63, 379/57, 455/33.1, 455/33.3, 455/33.4, 455/31.1, 455/33.2
• US Class Current: 455/466
• CPC Class Codes: H04W 16/14 Spectrum sharing arrangements between different networks

Abstract

The present invention provides a system and method for using the brief time intervals between cellular telephone calls on a primary cellular network to transmit and receive data over a second data-only network. The invention uses the built-in capability of the primary network to monitor and track each call and to identify the relatively short-duration intervals between each call to pinpoint when a short burst of data from the second network can be transmitted without interfering with primary network calls. The data network includes a separate telephone exchange. Selected base stations of the primary cellular network are shared with the data-only network. Land lines or other connections link the data network exchange with the shared base stations. Preferably, the data network is accessible via a public packet data network. Data calls on the second network are directed to the shared base stations and inserted into the brief intervals between primary network calls. The data calls provide discontinuous, "virtual" connections between the users of the data network. A particular advantage of the invention is that it allows the cellular base stations, transceivers, and allocated frequencies to be shared between a primary and a secondary cellular telephone network, without interfering with or reducing the capacity of the primary network. The invention works with analog or digital primary cellular networks, including those using multiple access methods such as TDMA. A method of carrying out the invention is also disclosed.

Claims

1. In a cellular telecommunications system in which a predominately voice-carrying first cellular network includes one or more cellular telephone exchanges operatively connected to a plurality of cellular base stations located throughout a service region, each of the base stations including a plurality of first network transceivers which operate at one or more predetermined frequencies, the transceivers each providing at least one cellular channel which carries first network calls to and from mobile cellular telephones, including a base station channel monitor for determining, for each transceiver, when one first network call has ended and the channel is idle and available to carry another first network call, and including a base station controller operatively connected to the transceivers and the channel monitor, the base station controller directing incoming first network calls to idle channels, each cellular channel being at least briefly idle between the end of one first network call on the channel and the beginning of the next first network call, a system for using the base stations and transceivers of the first cellular network to carry packetized data comprising:

a cellular data network operatively connected to a plurality of base stations, said cellular data network sharing at least some base stations and transceivers with the first cellular network, said cellular data network being connected to a public packet data network and selectively transferring data packets between users of the public packet data network and mobile cellular data stations, each said shared base station which is shared by both the first cellular network and said cellular data network further including;

a first network communication link operatively connecting said shared base station and the first cellular network for carrying first network calls to and from the base station;

a second network communication link operatively connecting said shared base station and said cellular data network for carrying data packets to and from the base station;

an operative connection between said first network communication link and the base station controller of said shared base station for routing first network calls to and from the transceivers within the base station, the base station controller being also operatively connected to the base station channel monitor for identifying intervals between first network calls;

an operative connection between said second network communication link and the base station controller of said shared base station for routing data packets to and from the same transceivers within the base station used to carry the first network calls; and

a data packet call controller operatively connected to the base station controller and said second network communication link for selectively supplying and retrieving data packets to and from the base station controller in response to the base station controller routing one or more data packets through a selected transceiver in said shared base station, said base station controller routing data packets through a selected transceiver during the intervals between first network calls on the cellular channel carried by the transceiver, whereby the transceivers and cellular channels used by said shared base station carry predominately voice calls over the first cellular network and intermittently carry data packets from the cellular data network over the same cellular channels and transceivers.

2. The system of claim 1 including, in each of said shared base stations, a data buffer operatively connected to said data packet call controller for receiving and temporarily storing data packets from the public packet data network, said data packet call controller responding to the base station controller to retrieve selected data packets from said buffer such that the data packets are directed to available cellular channels during the intervals between first network calls.

3. The system of claim 2 in which the predominately voice-carrying first cellular network provides multiple cellular channels on selected predetermined cellular frequencies through the use of multiplexing, whereby each transceiver in said shared base stations carries a plurality of cellular channels, including a multiplex controller at each said shared base station, and said data packet call controller being operated in coordination with said multiplex controller at each shared base station for inserting data packets from said buffer in the available cellular channel.

4. The system of claim 1 in which the predominately voice-carrying first cellular network provides multiple cellular channels on selected predetermined cellular frequencies through use of time division multiplexing, whereby each transceiver in said shared base stations carries a plurality of cellular channels in different predetermined time slots, including a time slot controller at each said shared base station, and said data packet call controller being operated in coordination with said time slot controller at each shared base station for inserting data packets from said buffer in the time slot of the available cellular channel during intervals between first network calls.

5. A method of sharing the cellular channels of a predominately voice-carrying first cellular network with packetized data cellular calls carried on a cellular data network connected to a public packet data network of the type which selectively transfers data packets via the cellular data network between users of the public packet data network and mobile cellular data stations, the first cellular network being of the type that includes a plurality of base stations each having a plurality of transceivers which operate at one or more predetermined frequencies, the transceivers each providing at least one cellular channel which carries first network calls to and from mobile cellular telephones, and each base station includes a base station controller for directing incoming first network calls to idle channels carried by a selected transceiver at the base station, each cellular channel being at least briefly idle between the end of one first network call on the channel and the beginning of the next first network call, the method comprising the steps of:

operatively linking the cellular data network to at least some of the base stations used by the first cellular network to provide shared base stations used by both the cellular data network and the first cellular network and, at each said shared base station;

operatively connecting the first cellular network to the base station controller, wherein the base station controller directs first network calls to and from transceivers within the base station;

operatively connecting the cellular data network to the same base station controller used in the preceding step, wherein the base station controller directs data packets carried via the cellular data network to and from transceivers within the base station, and;

the base station controller directing first network calls from the first cellular network and data packets from the cellular data network to cellular channels carried by selected transceivers in the base station in accordance with the following step;

when the base station controller identifies idle periods on a channel between the end of one first network call and the beginning of the next first network call, the base station controller selectively directs one or more data packets from the cellular data network to the transceiver carrying such channel for receipt or transmission of the one or more data packets during the intervals between first network calls, whereby the transceivers and cellular channels used by the shared base station carry predominately voice calls over the first cellular network and intermittently carry data packets from the cellular data network over the same cellular channels and transceivers.

6. A method as in claim 5 including, at each shared base station as part of the step of operatively connecting the cellular data network to the base station used to direct first network calls, providing a data buffer for temporarily storing data packets from cellular data calls in the operative connection between the base station and the cellular data network, including the step of selectively storing one or more data packets in the data buffer until the base station controller directs the one or more data packets to a selected cellular channel, and further including, in the step of selectively directing one or more data packets from the cellular data network to the transceiver carrying the selected channel, retrieving the one or more stored data packets from the data buffer for transfer to the transceiver carrying the selected channel during the interval between first network calls.

7. A method as in claim 5 in which the first cellular network uses time division multiplexing to provide multiple first network cellular channels on selected predetermined frequencies, said step of the base station controller selectively directing one or more data packets from the cellular data network to the transceiver including, for each first network cellular channel into which data packets are inserted, inserting the data packets into the time division of the cellular channel.

8. A method as in claim 5 in which the first cellular network uses multiplexing to provide multiple first network cellular channels on selected predetermined frequencies, said step of the base station controller selectively directing one or more data packets from the cellular data network to the transceiver including, for each first network cellular channel into which data packets are inserted, inserting the data packets into the available multiplexed cellular channel.