Combined gps and wide bandwidth radiotelephone terminals and methods

COMBINED GPS AND BROADBAND RADIO TELEPHONE TERMINALS AND METHODS

FIELD OF THE INVENTION

In general, the invention relates to wireless communication systems and methods, and more particularly to the field of mobile radio terminals.

BACKGROUND OF THE INVENTION

In general, radio communication systems are used for the transmission of voice and data between a large number of subscribers within a defined geographical area. For example, analog cellular telephone systems, known as AMPS, ETACS, NMT-450 and NMT-900, have been successfully deployed worldwide. The IS-54B (and its successor IS-136) digital telephone system for mobile radio has recently been introduced in North America and the GSM system in Europe and is currently being rolled out. These and other systems are described, for example, by Balston et al. in Cellular Radio Systems (Artech House, Norwood, MA, 1993). In addition to the systems described above, the Personal Communication Services (PCS) is still in development. Currently, PCS systems include IS-95, PCS-1900 and PACS in North America, DCS1800 and DECT in Europe, and PHS in Japan. These PCS systems operate in the 2 GHz band of radio spectrum and are commonly used in high speed communication systems for voice and data.

FIG. 1 illustrates a conventional terrestrial radio communication system 20 in which any of the above-mentioned wireless communication standards can be used. The radio communication system may consist of one or more mobile radio terminals 22, which are in communication with a plurality of base stations 26 and mobile phones.

EE 200000337 ega Cellular Services 24 provided by the MTSO (Mobile Telephone Swiching Office) 28 Although Figure 1 shows only three cellular cells 24, a typical cellular wireless network may include hundreds of cellular cells, consist of more than one MTSO 28, and serve thousands of radiocommunications. mobile terminals 22.

Generally, cellular cells 24 are nodes of the communication system 20 that make connections between mobile radio terminals 22 and MTSO 28 using base stations 26 serving cellular cells 24. The control channel is a shared channel used to transmit cellular cell identification and search information. Voice and data information is transmitted over a communication channel. Communication system 20 and duplex radio link 30 may establish a Public Switched Network (PSTN) between two mobile radio terminals 22 or between a mobile radio terminal 22 and a fixed telephone 32 user.

Telephone Network) 34 communications. The radio communication between the cellular cell 24 and the mobile communication terminal 22 is usually controlled by the base station 26. In this connection, the base station 26 acts as a data and speech signal transmitting station.

Figure 2 illustrates a conventional satellite radio communication system 120.

The satellite communication system 120 may be used to perform similar functions to that of the conventional terrestrial radio communication system 20 shown in Figure 1. Specifically, the satellite radio communication system 120 typically comprises one or more satellites 126 serving as transmitting stations or transponders between one or more terrestrial stations 127 and satellite radio terminals. Cable 126 is connected to satellite radio mobile terminals 122 and terrestrial stations 127 via duplex link 130. Each of the ground stations 127 may in turn be connected

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PSTN 132, which allows interconnection of mobile radio terminals 122 and communication between mobile radio terminals 122 and conventional terrestrial mobile terminals 22 (Figure 1) or fixed telephones 32 (Figure 1).

The satellite radio communication system 120 may use a single antenna beam covering the entire area served by the system; or, as shown in Figure 2, designed to emit a plurality of beams 134 having a minimum overlap, each beam serving a single geographic region 136 separate from the system service area. The functions of the cable 126 and its coverage area 136 may be similar to those of the base station 26 and the cell 24 of the terrestrial radio communication system 20, respectively.

Thus, the satellite radiocommunication system 120 may be used to perform the same functions as conventional terrestrial radiocommunication systems. In particular, the satellite radiotelephone communication system 120 may find use in areas with a sparse population spread over a large geographical area or where severe natural conditions render the establishment of fixed or terrestrial radiocommunication infrastructure economically impractical.

As the radiocommunication industry continues to evolve, new technologies are likely to integrate into these radiocommunication systems to expand the capabilities of the services provided. One such technology to consider is the Global Positioning System (GPS). Therefore, it is desirable to set up a mobile radio terminal with an integrated GPS receiver. It is self-evident that the terms "Global Positioning System" or "GPS" are used to define any space-based system which measures the position of terrestrial points, including the European satellite navigation system GLONASS.

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The GPS system is depicted in Figure 3. As is well known to those skilled in the art, GPS is a space-based triangulation system that uses satellites 302 and computers 308 to measure the location of points anywhere on the earth. The GPS system was originally created by the United States Department of Defense as a navigation system. Compared to other terrestrial systems, the GPS coverage may be unlimited, the system may operate 24 hours a day, regardless of the weather, and may have a high degree of accuracy. While GPS technology, which provides the highest level of accuracy, was left for military use by the government, services with lower accuracy were made available for civilian use.

In operation, a set of 24 satellites 302 orbiting the globe continuously emits a GPS radio frequency signal in predetermined frequency packages. The GPS receiver 306, such as a portable GPS receiver with a GPS processor, receives a radio signal from the nearest GPS satellite and measures the time it takes for the radio signal from the GPS satellite to propagate to the GPS receiver antenna.

By multiplying propagation time by the speed of light, the GPS receiver can calculate the distance to each satellite in view. By using additional information transmitted by satellites in a radio signal, which includes satellite orbit and velocity data and their correlation with the satellite clock, the GPS processor can calculate the position of the GPS receiver by triangulating.

Published International Application WO 97/14056 describes a combined shared electrical circuit GPS and communication system. The combined system comprises an antenna for receiving data corresponding to a GPS signal, a frequency converter connected to the antenna, a frequency synthesizer connected to a frequency converter, an analog-to-digital converter connected to the frequency converter and a processor connected to the frequency converter. The processor processes the data contained in the GPS signal to determine the pseudorange based on the data contained in the GPS signal. The integrated communication receiver includes the common components, which are at least one antenna, frequency converter, frequency synthesizer and analog-to-digital converter. Typically, in certain embodiments, the process also includes demodulation of the received communication signals as well as control of the modulation of data transmitted as communication signals over the communication channel.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a wireless communication terminal incorporating a Global Positioning System (GPS) receiver.

Another object of the present invention is to provide a mobile radio terminal incorporating a GPS receiver which is inexpensive to manufacture and effective in use.

According to the present invention, these and other objects have been achieved by a combination of a GPS and a wireless terminal with a wireless broadband radiotelephone, in which many components are shared. In particular, the present invention has achieved the use of a common intermediate band (IFriba) for a GPS receiver and some standard satellite or terrestrial radiotelephone systems. Moreover, some standards for satellite or terrestrial radiotelephone systems fulfill a common function of processing a signal to find long pieces of code in it. Thus, the only major difference remains the difference in acceptable radio frequencies.

According to the present invention, the mobile radio terminal comprises a GPS radio frequency (RF) receiver and a broadband radiotelephone radio frequency (RF) receiver having a bandwidth of at least half the GPS chip frequency. The mobile radio terminals also include a common intermediate frequency (IF) stage that works with both the GPS RF receiver and the RF receiver of the broadband radiotelephone. The demodulator works with a commonly used IF stage. As a result, a common electrical circuit may be used, except for the GPS RF input terminals and the broadband radiotelephone RF receiver input terminals, both operating at different frequencies. However, it is possible to produce both input stages as a single, dual-band input stage to ensure low manufacturing costs. This provides the opportunity to use high-efficiency operations io.

In a preferred embodiment of the present invention, the RF receiver of a wideband radiotelephone is a code division multiple access (CDMA) RF receiver, which includes a Universal Mobile Terminal System (UMTS) and is also known as CDMA or Time Division Multiple Access (TDMA) radio. Both CDMA and TDMA receivers can have bandwidths of the order of 1 MHz, which is comparable to GPS bandwidths. Therefore, regardless of the various acceptable RF frequency spectra, many components may be shared. For CDMA, the demodulator is preferably a CDMA wide spectrum aggregator, and for TDMA, preferably a TDMA demodulator.

In fact, thanks to approximately the same bandwidths, a combined GPS / CDMA receiver can be created, with the CDMA receiver having the same bandwidth as the GPS receiver. In this case, intermediate frequency (IF) and demodulation can be effectively combined.

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It is also possible to combine parts of the GPS RF receiver and TDMA / CDMA RF receiver. For example, a dual band antenna may be provided, wherein the GPS RF receiver includes a GPS RF filter sensitive to the dual band antenna and the wide band radiotelephone RF receiver comprising a wide spectrum RF filter sensitive to the dual band antenna.

In this case, a common wide band RF amplifier and filter may be used in the RF part.

Other embodiments of the present invention may be embodied separately as GPS and CDMA / TDMA IF steps, whereby all components are used separately or where some components, such as heterodyne, are used together. In other possible embodiments, there may be a common demodulator, such as a spectrum aggregator, but all other components are separate.

In accordance with the present invention, the radio reception methods used in a mobile terminal include receiving a GPS RF signal at a predetermined chip frequency on a first RF channel and receiving a broadband radiotelephone RF signal on a second RF channel, wherein the RF signal of the wideband radiotelephone is The GPS RF signal and the broadband radiotelephone RF signal are then demodulated in a shared demodulator. A demodulator can

2o include a shared mixer. Accordingly, a high-efficiency, low-cost wireless terminal and a radio reception method may be realized.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 illustrates a conventional terrestrial (mobile) radio communication system.

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Figure 2 illustrates a conventional satellite radio communication system (satellite communication system).

Figure 3 shows a Global Positioning System (GPS).

Figures 4-9 illustrate methods of receiving mobile radio terminals and radio communications in accordance with the present invention.

Figure 10 graphically illustrates the correlation losses caused by filtering in the GPS receiver.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention will now be described in more detail with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. However, the present invention may be embodied in a number of different forms and should not be construed as limited to the embodiments disclosed herein; rather, embodiments are provided for the purpose of the present disclosure to be complete and exhaustive and to fully convey the scope of the invention to those skilled in the art. Throughout the description, like numbers refer to the same elements. The present invention is based on the fact that it employs a common intermediate band (IF band) for the GPS 20 receiver and some standard satellite or terrestrial radiotelephone systems, and that some of these standards have the common function of processing the signal to find long pieces of code. As a result, the elements of the GPS receiver and the receiver of the broadband radiotelephone can be successfully combined to realize mobile radio terminals and reception methods that allow efficient and inexpensive operation.

The details of GPS systems and broadband radiotelephone systems are their own

EE 200000337 Α is well known to those skilled in the art and does not require further explanation. Similarly, the subsystems that each system consists of are well known to those skilled in the art and do not require further explanation. Accordingly, the present detailed description of the invention, at the block diagram level, describes various embodiments which may demonstrate

An efficient connection between a GPS receiver and a broadband radiotelephone receiver.

FIG. 4 illustrates mobile radio terminals of the present invention and a method of receiving a radio communication. As shown in FIG. 4, mobile radio terminals and radio reception methods include a GPS RF receiver io 41, and a wideband radiotelephone RF receiver 420 having a bandwidth of at least half

GPS chip frequency. The commonly used IF stage 430 works with both the GPS RF receiver

410 as a broadband radiotelephone RF receiver 420. A demodulator, such as a spectrum combiner 450, is suitable for processing the signal from the IF stage.

The broadband RF receiver 420 is preferably CDMA or

TDMA receiver. It is also preferred that the GPS RF Receiver 410 and the Broadband Radiotelephone RF Receiver 420 have similar bandwidths in different parts of the RF spectrum. It would be even better if the GPS RF receiver 410 and the broadband radiotelephone RF receiver 420 had identical bandwidths in different parts of the RF spectrum.

Specifically, there are a number of cellular phone standards with an IF bandwidth of about 30 kHz, such as AMPS or digital AMPS, or about 270 kHz, such as GSM. These narrow bandwidths may be insufficient to receive a GPS signal with a bandwidth of 1 MHz. However, there are also many mobile phone standards with an IF bandwidth of at least 1 MHz. These include IS-95

CDMA standard 1.2 MHz bandwidth, DECT standard (Digital European Cordless

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Teleohone), the TDMA standard bandwidth is approximately 1 MHz and the proposed Japanese CDMA standard bandwidth is up to 5 MHz. Satellite communication systems (such as GLOBALSTAR), which have the same high bandwidths as CDMA signal processing, are also being designed and developed. Accordingly, the present invention enables a common IF processing of a GPS and a wideband radiotelephone receiver signal and a common spectrum aggregation process including demodulation, correlation and baseband processing. Matching can be done for different RF frequencies that are received with the same bandwidth.

In particular, it is known that the correlation loss caused by filtering in the GPS receiver is a function of the bandwidth to the frequency ratio. These correlation losses increase rapidly for bandwidths less than 50% of the chip frequency. See. Figure 10 shows a reproduction of Figure 12 textbooks entitled "Global Positioning System: Theory and Applications, Vol. \, p. is 35Γ, which are incorporated herein by reference for a better understanding of the invention. For example, if the chip frequency is 1.023 MHz and losses of up to 3 dB are acceptable, the receiver may have a single sideband width (half the bandwidth) of 0.25 x 1.023 MHz or approximately 255 kHz. The total bandwidth is then about 511 kHz or about half the chip frequency. As shown in Figure 10, at narrow bandwidths, correlation losses increase rapidly.

Figure 5 shows another general embodiment of the present invention. This embodiment is implemented by means of a separate GPS RF receiver 510 and a wideband radiotelephone RF receiver 520, but also by a separate GPS IF stage 540 and a wide band radiotelephone IF25 520. A common demodulator is used, which is a spectrum concentrator 550. This embodiment may be desirable if separate IF steps are preferred.

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Figure 6 illustrates in more detail the combined GPS / wideband radiotelephone terminal and methods. As shown in Figure 6, the GPS RF portion includes a GPS antenna 612, an RF filter 614, an RF amplifier 616, and an RF filter 618. The RF portion of a wide band radiotelephone includes a cellular antenna 611, an RF filter 613,

RF amplifier 615 and RF filter 617. The terminal is provided with a separate GPS mixer 630 and a high bandwidth radiotelephone mixer 640, each mixer utilizing a separate heterodyne 632 and 642 respectively. The key 644 is provided for switching between the GPS and the wide band radiotelephone system. A common IF filter 646 and a common demodulator which is a spectrum extender 650 io (demodulator / correlator / baseband processor) are used. A common microprocessor 652 and a shared memory 654 are also used.

It will be appreciated by those skilled in the art that the terminals and methods depicted in Figure 6 may be realized by attaching a GPS antenna to a conventional CDMA mobile terminal.

612, RF filter 614, RF amplifier 616 and RF filter 618, mixer 630, heterodyne 632, and key 644, to enable the combined device to operate in dual mode GPS / CDMA mode depending on key 644 setting and digital signal processing by correlator / baseband processor 650 and microprocessor 652 by. The software may require tuning to look for different codes and slightly different code chip rates, and then use the information obtained to perform both tasks appropriately.

With GPS reception, code phase shifts can be found for each visible satellite, and data demodulation allows for time and ephemeris data. The data can be analyzed using a microprocessor 652 to determine position. When using a mobile phone, the polarity of the code contains data that is further processed by CODEC to receive a call. It is also to be understood that Figure 6 does not, for the sake of clarity, show the transmission path used in the CDMA mobile terminal.

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It will be appreciated that in the terminals and methods shown in Figure 6, the phase shifts of the code for each visible satellite are obtained either from an internal storage medium or from information transmitted over a mobile telephone channel. This information may be stored in memory 654 and then switched to GPS reception mode for use with a CDMA mobile phone. The code phase shift information may be transmitted via a mobile telephone channel to a server where location is determined by additional information from the exchange.

Figure 7 shows an alternative embodiment of the present invention. The io elements in Figure 7 correspond to the elements in Figure 6 except for the common oscillator

732, which is used as both a GPS mixer 630 and a high bandwidth radiotelephone mixer 640. The use of a common heterodyne in a dual mode GPS / radiotelephone terminal is described in application no. No. 08 / 925,566 to Horton and Camp Jr., entitled "Systems and Methods for Sharing Reference Frequency Signals Within a Wireless Mobile Terminal Between a Wireless Transiver," belonging to the present invention, which are incorporated herein by reference for a better understanding of the present invention. In the embodiment of FIG. 7, the circuit controlling the oscillator 732 may be tuned to generate a suitable frequency signal and to receive either GPS or high bandwidth radiotelephone signals.

Figure 8 shows another embodiment using a common mixer 830 and a common heterodyne 832. Accordingly, key 844 is used to provide two RF signals to mixer 830. As in Figure 7, the oscillator can be re-tuned to generate a suitable frequency signal.

Structures with the same architecture can be used for GPS / DECT and GPS / WCS terminals and methods. In a DECT system that does not have a correlator function, it may be necessary to equip the digital hardware with proprietary or scalable programs to realize correlation in digital resources.

Figure 9 illustrates terminals and methods for sharing parts of an RF system. As shown in Figure 9, dual-band GPS and cellular antenna 910 can receive both GPS and high bandwidth radiotelephone signals. A key pair 911 and 912 may be used to switch the appropriate GPS RE filter 914 or mobile phone filter 913. Although these filters are shown separately in FIG. 10, the filters may be implemented as a common filter having removable or switchable elements. This is followed by an RF broadband amplifier 915 and a mixer 830. As previously described, the embodiment of FIG. 9 also includes an oscillator 832, an IF filter 646, a spectral converter 650, a microprocessor 652, and a memory 654. It is also to be understood that dual-band GPS and cellular antennas may be replaced by 15 separate GPS antennas and cellular telephone antennas in combination with a common broadband amplifier.

The drawings and the description of the invention disclose typical preferred embodiments of the invention, and although specific terms are used, preferred embodiments are used only in a general and descriptive sense and are not intended to limit the scope of the invention as defined by the following claims.