HK1085575B - Spread-spectrum changeable base station - Google Patents

Description

Base station with variable spread spectrum

The present application is a divisional application of an invention patent application having an application number of "01134750.3", an application date of "16.6.1995", and an invention name of "a base station with variable spread spectrum".

Technical Field

The present invention relates to spread spectrum communications, and more particularly to a method and system for handing off a base station among a plurality of users in a spread spectrum network.

Background

Spread spectrum modulation is a well-developed technique based on generating a chipping sequence and processing a data signal using the spread spectrum of the chipping sequence. Using this technique, a communication link can be established between a transmitter and a receiver at a remote location. Also, the network may be established using conference call spread spectrum techniques. Conference call spreading techniques are disclosed in U.S. patent 5179572 entitled "spread spectrum conference call system and method" issued to Schilling and U.S. patent 5263045 entitled "spread spectrum conference call system and method" issued to Schilling.

A problem may exist when the spread spectrum conference call system is set up, but the base station may need to change hands. For example, in a military environment, a row of infantries may use spread spectrum modulation for conference calls among the members of the row. A particular squad in the row may be designated as the base station. The cited prior art does not teach how to change base stations from bank to bank or what happens between the teams of the bank if it needs to perform such a change.

Disclosure of Invention

The general object of the present invention is a conference call spread spectrum communication system and method in which the base station can be changed as required.

Another object of the invention is a spread spectrum conference call technique where any cell can act as a base station.

In the present invention, as embodied and broadly described herein, a spread spectrum system having a plurality of spreading units is provided. Each spreading unit is capable of operating as a base station and as a remote station. Each spreading unit includes a base station subunit, a remote station subunit, and a command subunit.

The method of the present invention includes receiving, in the base station subunit, at a first frequency, a plurality of spread spectrum signals transmitted from a plurality of spreading units. The plurality of spread signals are despread and demodulated in the base station subunit to produce a plurality of demodulated signals. A plurality of demodulated signals are combined and local signals such as data signals or voice signals from the users of the units are also combined to produce a combined signal. The base station subunit converts the combined signal to a base station data signal. The base station subunit spread-spectrum processes the base station data signal, and transmits the spread-spectrum processed base station data signal at the second frequency as a base station spread-spectrum signal using radio waves.

At each spreading unit, the base station spread signal is received at its corresponding remote station subunit at the second frequency. The remote station subunit includes circuitry for despreading the base station spread spectrum signal and demodulating the despread base station spread spectrum signal into a base station analog signal. The remote station subunit may also take a local voice signal, designated herein as a remote station analog signal, and convert the remote station analog signal into a remote station data signal. The remote station subunit spread spectrum processes the remote station data signal and transmits the remote station data signal as one of a plurality of spread spectrum signals at a first frequency.

The operator may initiate the base station subunit by issuing a command signal from the command subunit. Thus, when a command signal is issued, the command signal is broadcast to a plurality of spreading units. At each spreading unit, a command signal is received in a corresponding remote station subunit, and the remote station subunit is activated in response to the received command signal.

Additional objects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may also be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate preferred embodiments of the invention and together with the description, serve to explain the principles of the invention.

FIG. 1 is a block diagram of a base station subunit;

FIG. 2 is a block diagram of a remote station subunit; and

FIG. 3 is a block diagram of a command subunit.

Detailed Description

Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout the several views.

The present invention provides a unique solution to the problem of multiple spreading units used in a mobile environment, where any one spreading unit is vulnerable to neutralization (neutralization), while maintaining communication between all spreading units is still critical. Spread spectrum variable base stations find application in squadron lines, in military environments, or in law enforcement applications, where a mobile base station may be set up to control a plurality of spread spectrum remote station units. A problem posed by each of these applications is that which occurs when a base station unit becomes disabled or inoperative. In military environments, base stations may be damaged. In law enforcement situations, there may be a requirement for mobility of multiple spread spectrum units, and the base station changes from one unit to another.

A spread spectrum system has a plurality of spreading units, each having a base station subunit, a remote station subunit and a command subunit. The use of the term "subunit" to designate a base station subunit, a remote station subunit, and a command subunit is for the purposes of describing the present invention. The invention may be constituted as a general integrating unit or as a mixture of more than one unit.

A base station subunit is schematically shown in fig. 1. The base station subunit comprises receiving means, despreading means, demodulation means, combining means, transformation means, spreading processing means and transmitting means. The despreading means is connected between the receiving means and the demodulation means. The combining means is connected to the demodulating means and the transforming means. The spread spectrum processing device is connected to the conversion device and the transmission device.

The receiving apparatus is shown in fig. 1 with an antenna 11 connected to a radio frequency/intermediate frequency (RF/IF) amplifier and filter section 12. The despreading means are shown as a number of mixers 13, 14, 15. Each mixer 13, 14, 15 has a shaping sequence g1(t), g2(t), … … gn (t), respectively, for mixing with the received spread spectrum signal. The plurality of trim sequences coincide with the trim sequences of the despread desired spread spectrum signal.

The demodulating means and the combining means are indicated as demodulator 16 and combiners 17A, 17B. The combiners 17A, 17B may be a single combiner or separate combiners that perform the combining function. The conversion means are shown as analog-to-digital converters 18. The spread spectrum processing means is shown as a product device (product device)19 with a trimming sequence for spreading the data signal of the analog to digital converter 18. The transmitting means are shown as a transmitter 20 and an antenna 21.

The RF/IF amplifier and filter circuit 12 is coupled to an antenna 11 and a plurality of mixers 13, 14, 15. A plurality of mixers 13, 14, 15 are coupled to a demodulator 16 and to combiners 17A, 17B. The analog-to-digital converter 18 is connected to the combiner 17B and the product device 19. Transmitter 20 is coupled to product device 19 and antenna 21. The antenna 21 and the antenna 11 may be the same antenna or different antennas with suitable isolation circuitry.

The RF/IF amplifier and filter circuit 12 receives a plurality of spread spectrum signals transmitted from a plurality of spreading units at a first frequency f 1. The plurality of spread signals are despread by a plurality of mixers 13, 14, 15. The outputs of the plurality of mixers 13, 14, 15 are a plurality of despread signals. Demodulator 16 demodulates the plurality of despread signals to produce a plurality of demodulated signals. The combiner 17A combines the plurality of demodulated signals. The combined plurality of demodulated signals and the local signal from the base station may be combined using a second combiner 17B to produce a combined signal. The term "combined signal" as used herein is an analog signal comprising the combined demodulated signal of the base station's voice and combiners 17A, 17B.

The combined signal is converted to a base station data signal by an analog to digital converter 18. The term "base station data signal" as used herein is a digital signal from the analog-to-digital converter 18 and includes both analog and data signals at the base station.

The product device 19 processes the base station data signal from the analog-to-digital converter 18 with base station trim sequence spread spectrum. The spread spectrum processed base station data signal is transmitted by transmitter 20 as a spread spectrum signal for the base station at the second frequency. The antenna 11 and the antenna 21 may be a single antenna for the receiver and the transmitter.

In fig. 2, there is shown a remote station subunit comprising a receiver part, a transmitter part, receiving means, despreading means and demodulation means. The transmitting section includes a converting means, a spread spectrum processing means, and a transmitting means. The receiving device receives the base station spread spectrum signal at the second frequency. The despreading means despreads the base station spread signal as a despread base station spread signal. The demodulation means demodulates the despread base station spread signal into a base station analog signal.

The conversion means converts the remote station analog signal to a remote station data signal. The remote station analog signal is typically the remote station's voice. The base station analog signal is typically a plurality of voice signals from the base station. The spread spectrum processing means processes the remote station processed signal with a remote station shaping sequence. The transmitting means transmits the spread-spectrum processed remote station data signal at the first frequency as one of a plurality of spread-spectrum signals, which are received at the base station subunit.

As shown in fig. 2, the receiving apparatus includes an antenna 31 and an RF/IF amplifier and filter circuit 32. The despreading means and the demodulation means are implemented as a mixer 33 and a demodulator 34, respectively. The RF/IF amplifier and circuit 32 is connected between the antenna 31 and the mixer 33. The demodulator 34 is coupled to the mixer 33.

The base station spread spectrum signal at antenna 31 is amplified and filtered by the RF/IF. The base station spread signal is despread by mixer 33 using the base station trim sequence to produce a despread base station spread signal. The demodulator 34 demodulates the despread base station spread signal into a base station analog signal. The output of demodulator 34 is a plurality of voice signals from the base station.

The transmitter portion of the remote station subunit may have conversion means implemented as an analog-to-digital converter 35, spread spectrum processing means implemented as a production device 36 and transmission means implemented as a transmitter 37 connected to an antenna 38. The production device 36 is connected between the analog-to-digital converter 33 and the transmitter 37.

Analog-to-digital converter 35 converts the voice of the remote station signal, referred to herein as the remote station analog signal, to a remote station data signal. The remote station data signal is spread spectrum processed by the production equipment 36 using the remote station trim sequence. The output of the product device 36 is the spread-spectrum processed remote station data signal. Transmitter 37 transmits the spread-spectrum-processed remote station data signal as one of a plurality of spread-spectrum signals using antenna 38. Antennas 31 and 38 may be combined as a single antenna serving both functions.

The command subunit is shown in fig. 3. The command subunit includes an initiating device, a broadcasting device, and a receiving device. Upon initiation by a local user of that spread spectrum unit, the initiating device initiates a command signal. The command signal activates the base station subunit in that spreading unit. The broadcaster broadcasts the command signal to a plurality of spreading units. The receiving device receives the command signal while broadcasting from a different spreading unit. The activation means activates the remote station subunit upon receipt of the command signal.

The actuation means is shown as a push button switch 43 in figure 3. The broadcaster is shown as the transmitter portion of the transmitter/receiver 42. The transmitter transmits at frequency f 3. The receiving means is shown as a receiver part of the transmitter/receiver 42. The receiver receives at frequency f 3. The transmitter/receiver 42 is connected to the antenna 41 for radiating and receiving signals. The activation means includes circuitry for disconnecting the base station subunit and the remote station subunit activating a particular spread spectrum unit. The activation unit is shown as control circuit 44. The present invention may also replace voice signals with data.

In use, a particular spreading unit may operate with its active remote station subunit. Thus, the remote station subunit of that particular spreading unit receives the base station spread signal at the second frequency and despreads the base station spread signal as a despread base station spread signal. The despread base station spread signal is demodulated. Thus, that particular spreading unit receives all of the base station signals via its remote station subunit. When transmitted to the plurality of spreading units, that particular spreading unit converts the voice signal, implemented as an analog signal at the remote station, to a data signal at the remote station. The remote station data signal is spread spectrum processed and transmitted at a first frequency as one of a plurality of spread spectrum signals.

When a command signal is initiated by the user of that particular spreading unit by pressing button 43, that particular spreading unit switches from operating with the remote station subunit to operating with the base station subunit. At the same time, the command signal is radiated to another spreading unit of the plurality of spreading units. Upon receipt of the command signal, each spreading unit has its remote station subunit activated and thereafter operates in the remote station subunit mode. The particular spreading unit has then become the base station.

When operating as a base station, the particular spreading unit has its active base station subunit. Thus, the plurality of spread signals transmitted at the plurality of spreading units of each unit are received by the RF/IF amplifier and circuit 21 via the antenna 11. The plurality of spread signals are despread by a plurality of mixers 13, 14, 15 and demodulated by a demodulator 16 which outputs a demodulated signal. The plurality of demodulated signals from combiner 17A are voices from a plurality of remote stations. Voice from a plurality of remote stations is combined with the voice of the base station by combiner 17A and converted to a base station data signal by analog to digital converter 18. The base station data signal is spread spectrum processed by the product device 19 and transmitted by the transmitter 20 and via the antenna 21 at a second frequency.

It will be apparent to those skilled in the art that various changes can be made in the spread spectrum variable base station of the present invention without departing from the scope or spirit of the invention, and it is intended that the present invention cover modifications and variations of the spread spectrum variable base station provided consistent with the appended claims and their equivalents.

Claims (17)

1. A base station subunit for a wireless spread spectrum communication system, the base station subunit comprising:

an antenna for receiving a signal of a first frequency;

a plurality of mixers for mixing the received signal with a plurality of shaping sequences to produce a plurality of despread voice signals;

a combiner for combining said despread voice signal with a voice signal generated at said base station subunit;

a product device for mixing the combined signal with a trim sequence; and

an antenna for transmitting the mixed combined signal at the second frequency.

2. The base station subunit of claim 1 wherein said base station subunit further comprises a demodulator for demodulating said despread voice signals prior to combining.

3. The base station subunit of claim 1 wherein the combiner comprises a first combiner for combining the despread voice signal and a second combiner for combining the combined despread voice signal and the voice signal generated at the base station subunit.

4. The base station subunit of claim 1 wherein said base station subunit further comprises an analog-to-digital converter for converting said combined signal to a digital signal.

5. The base station subunit of claim 3 wherein the output of the first combiner is a combined voice signal of a plurality of remote units.

6. A base station subunit for a wireless spread spectrum communication system, the base station subunit comprising:

an antenna for receiving a signal of a first frequency;

a plurality of matched filters for mixing the received signals to produce a plurality of despread voice signals;

a combiner for combining said despread voice signal with a voice signal generated at said base station subunit;

a product device for mixing the combined signal with a trim sequence; and

an antenna for transmitting the mixed combined signal at the second frequency.

7. The base station subunit of claim 6 wherein said base station subunit further comprises a demodulator for demodulating said despread voice signals prior to combining.

8. The base station subunit of claim 6 wherein the combiner comprises a first combiner for combining the despread voice signal and a second combiner for combining the combined despread voice signal and the voice signal generated at the base station subunit.

9. The base station subunit of claim 6 wherein said base station subunit further comprises an analog-to-digital converter for converting said combined signal to a digital signal.

10. The base station subunit of claim 8 wherein the output of the first combiner is a combined voice signal of a plurality of remote units.

11. A base station subunit for a wireless spread spectrum communication system, the base station subunit comprising:

a receiving device for receiving a first frequency signal;

generating means for generating a plurality of despread voice signals using the received signal;

combining means for combining said despread voice signal with a voice signal generated at said base station subunit;

mixing means for mixing the combined signal with a trimming sequence; and

transmitting means for transmitting the mixed combined signal at a second frequency.

12. The base station subunit of claim 11 wherein the generating means is a plurality of mixers.

13. The base station subunit of claim 11 wherein the generating means is a plurality of matched filters.

14. The base station subunit of claim 11 wherein said base station subunit comprises a demodulator for demodulating said despread voice signals prior to combining.

15. The base station subunit of claim 11 wherein the combining means comprises a first combiner for combining the despread voice signal and a second combiner for combining the combined despread voice signal and the voice signal generated at the base station subunit.

16. The base station subunit of claim 11 wherein said base station subunit further comprises an analog-to-digital converter for converting said combined signal to a digital signal.

17. The base station subunit of claim 15 wherein the output of the first combiner is a combined voice signal of a plurality of remote units.