Wideband wireless basestation making use of time division multiple-access bus having selectable number of time slots and frame synchronization to support different modulation standards

• US 5,592,480 A
• Filed: 03/13/1995
• Issued: 01/07/1997
• Est. Priority Date: 03/13/1995
• Status: Expired due to Term

• Current Assignee: Treble Investments LLC (Intellectual Ventures LLC)
• Original Assignee: AirNet Communications Corporation (Tecore Incorporated)
• Inventors: Williams, Terry L., Schmutz, Thomas R., Carney, Ronald R.
• Primary Examiner(s): Safourek, Benedict V.
• Application Number:
  US08/402,585
• Time in Patent Office: 666 Days
• Field of Search: 370/18, 370/23, 370/57, 370/58.1, 370/67, 370/68, 370/70, 370/85.7, 370/95.3, 370/105.1, 370/123, 455/17, 455/33.1, 455/53.1, 455/102, 455/131, 455/142, 455/143
• US Class Current: 370/347
• CPC Class Codes: H04B 7/2646 for broadband transmission
• CPC Class Codes: H04W 88/08 Access point devices

Abstract

A wireless communication system basestation making use of a wideband, multichannel digital transceiver having incorporated therein a time division multiple-access (TDM) bus for providing digital samples of a plurality of wireless communication channels, wherein the time slot duration and frame rate of the TDM bus may be reconfigured. The invention allows various air interface standards, even those having different channel bandwidths, to be serviced by the same basestation, without having to install additional or different equipment, and by automatically redistributing signal processing resources, eliminating the need to reconfigure the basestation when different types of wireless signaling must be accommodated.

Claims

1. A basestation for processing signals in a multiple mobile subscriber unit wireless communication system comprising:

an antenna for receiving signals from a plurality of the mobile units as a composite radio frequency, RF, signal;

wideband digital tuner means, connected to the antenna, for down-converting a selected bandwidth of the RF signal to an intermediate frequency, IF, signal and for performing an analog to digital conversion on the IF signal, to provide a wideband digital tuner output signal;

digital channelization means, being connected to receive the wideband tuner output signal, and providing multiple digital channel signal outputs, each digital channel signal output having a predetermined channel bandwidth, and each digital channel signal corresponding to one of the signals received from one of the mobile units;

a plurality of digital signal processing means, for providing digitally processed channel signal outputs;

time division multiplex switching means, disposed between the multiple digital channel signal outputs and the plurality of digital signal processing means, the switching means for interconnecting any one of the multiple digital channel signal outputs to any one of the plurality of digital signal processing means; and

synchronization timing means, connected to control the time division multiplex means, to provide, at a frame rate which depends upon the predetermined bandwidth of the channel signals, a plurality of time slots, the number of time slots depending upon the number of digital channel signals.

2. The basestation of claim 1 wherein the signals received from the mobile units contain modulation, and the digital signal processors include demodulators to remove the modulation.

3. The basestation of claim 1 additionally comprising:

signal-transport encoding means, connected to the output of the digital signal processing means, for encoding the digitally processed channel outputs for further transmission to a mobile telephone switching office, MTSO.

4. The basestation of claim 3 wherein the signal-transport encoding means is a T1 encoder.

5. The basestation of claim 1 additionally comprising:

second digital channelization means, being connected to receive the wideband tuner output signal, and providing a second set of multiple digital channel signal outputs, each one of the second set of the digital channel signal outputs having a predetermined channel bandwidth which is different from the predetermined channel bandwidth of said above mentioned first digital channel signals, and each one of the second set of digital channel signals corresponding to one of the signals received from one of the mobile units.

6. The basestation of claim 1 additionally comprising:

second wideband tuner means, connected to the antenna, for downconverting a second selected bandwidth of the RF signal to a second intermediate frequency, IF, signal, and for performing an analog to digital conversion on the second IF signal, to provide a second wideband digital tuner output signal; and

second digital channelization means, being connected to receive the second wideband tuner output signal, and providing a second set of multiple digital channel signal outputs, each one of the second set of the digital channel signal outputs having a predetermined channel bandwidth which is different from the predetermined channel bandwidth of said above mentioned first digital channel signals, and each one of the second set of digital channel signals corresponding to one of the signals received from one of the mobile units.

7. A basestation as in claim 6 wherein the first and second set of digital channel signals are modulated in accordance with first and second standards, respectively.

8. A basestation as in claim 7 wherein the digital signal processors include a first set of digital signal processor means for demodulating said first set of digital channel signals, and a second set of digital signal processors for demodulating said second set of digital channel signals.

9. A basestation as in claim 7 wherein said first and second standards are each different one of a time division multiplex, TDMA, code division multiplex, CDMA, Advanced Mobile Phone System, AMPS, Personal Communications System, PCS, or Groupe Especiale Mobile, GSM.

10. A basestation as in claim 1 additionally comprising:

basestation controller means, connected to the time division multiplex switching means and the digital signal processing means, for maintaining a list of unused digital signal processing means that are not presently interconnected through the time division multiplex switching means to one of the digital channel outputs, and for dynamically allocating digital signal processing means from the list of unused digital signal processing means to be interconnected to one of the digital channel outputs only when the digital channel output contains an active signal being transmitted by the mobile unit which has not yet been assigned to one of the digital signal processing means.

11. A basestation as in claim 1 wherein the time division multiplex switching means further comprises:

a time division multiplex, TDM, data bus including data lines;

basestation controller means, connected to the TDM bus, and to generate TDM bus synchronization signals and driver address signals, the TDM bus synchronization signals used to identify access timeslots on the TDM bus; and

TDM bus driver means, connected to the TDM bus, the basestation controller means, and at least one of the digital channel signals, for receiving the TDM bus synchronization signals and the driver address signals, for storing the driver address signals, and for asserting the digital channel signal on the TDM bus when the value of driver address signals corresponds to the value of the bus synchronization signals, thereby indicating that a timeslot associated with the digital channel signal is currently active.

12. A basestation as in claim 11 wherein the basestation controller means, connected to the TDM bus, additionally generates receiver address signals, and the time division multiplex switching means additionally includes:

TDM bus receiver means, connected to the TDM bus, the basestation controller means, and at least one of the digital signal processor means, for receiving the TDM bus synchronization signals and the receiver address signals, for storing the receiver address signals, and for reading a signal asserted on the TDM bus and providing such asserted signal to the digital signal processor means when the value of receiver address signals corresponds to the value of the bus synchronization signals, indicating that a timeslot associated with the digital signal processor is currently active.

13. A wideband basestation as in claim 6 wherein the first and second channelizers each comprise:

a convolutional digital filter, connected to receive the respective one of the digitized wideband signals; and

a fast Fourier transform, FFT, processor, connected to receive the output of the convolutional digital filter, and to provide the digital channel signals.

14. A basestation as in claim 1 additionally comprising:

a second plurality of digital signal processing means, connected to receive digital input signals from a communication signal source;

a wideband digital combiner, being connected to receive a second plurality of digital channel signals, and to provide a composite digital signal for transmission;

wherein the time division multiplex switching means is also disposed between the second plurality of digital signal processors and the wideband digital combiner, the switching means connecting any one of the second set of digital signal processors to any one of the digital channel signals input to the combiner;

a wideband digital exciter, connected to receive the composite digital signal and to provide a combined RF signal; and

a transmit antenna, connected to receive the combined RF signal and the radiate the combined RF signal.

15. A basestation as in claim 14 additionally comprising:

basestation controller means, connected to the time division multiplex switching means and the first and second plurality of digital signal processing means, for maintaining a list of all unused digital signal processing means that are not presently interconnected through the time division multiplex switching means to one of the digital channel outputs, and for dynamically allocating digital signal processing means from the list of unused digital signal processing means to function as one of the first or second digital signal processing means only when the digital channel output contains an active signal being transmitted by the mobile unit which has not yet been assigned to one of the digital signal processing means, or when the digital inputs from the communications source are active.

16. A wideband basestation transceiver including:

a wideband digital tuner that provides a wideband digital signal at an output;

a digital channelizer, connected to the wideband tuner, to produce a plurality of sampled channel signals, with each channel signal representing signal energy in one of a plurality of radio frequency channels serviced by the basestation;

a time division multiple-access, TDM, data bus;

means for selectively connecting the digital samples of each channel signal, in turn, to the TDM bus;

basestation controller means, for controlling the means for selectively connecting the digital samples of each channel signal to the TDM bus, by so connecting each channel signal in a predetermined timeslot, in a predetermined order;

means, coupled to the TDM bus, for selecting the digital samples in a particular timeslot, and for generating a reconstructed channel signal thereby;

means for allocating a demodulator to be coupled to the reconstructed channel signal when the associated radio frequency channel is active, the demodulator providing a demodulated channel signal;

means for allocating a T1 line encoder to the demodulated channel signal, to format the demodulated channel signal for transmission over a T1 span line;

and

synchronization and clock generation means, connected to the base station controller means, for selecting a number of time slots, as well as a bus frame rate to be used on the TDM bus, such that the number of time slots and the bus frame rate depend upon, respectively, the number of the channel signals and the bandwidth of each of the channel signals provided by the digital channelizer.