GB2399993A

GB2399993A - Dual-mode radio communications device

Info

Publication number: GB2399993A
Application number: GB0307245A
Authority: GB
Inventors: Richard Ormson
Original assignee: NEC Technologies UK Ltd
Current assignee: NEC Technologies UK Ltd
Priority date: 2003-03-28
Filing date: 2003-03-28
Publication date: 2004-09-29
Anticipated expiration: 2023-03-28
Also published as: GB0307245D0; GB2399993B

Abstract

The invention provides for a radio communications device comprising a power amplifier for delivering transmission signals to an antenna, first modulating means of a first radio technology arranged to deliver a modular signal to the power amplifier, second modulating means of a second radio technology, and routing means arranged to deliver a signal from the said second modulating means to the said power amplifier. The modulation schemes may be related such that both are linear and are arranged to operate in similar wavebands. The invention may also include a second power amplifier wherein the routing means delivers a third radio technology to said second power amplifier. Said radio technologies may include WODMA, EDGE and GSM respectively.

Description

1 2399993

RADIO COMMUNCATIONS DEVICE

The present invention relates to a radio communications device and, in particular, to a mobile radio communications device arranged for use in accordance with one of a plurality of radio technologies.

As the number of cellular communication standards increases, so does the desire for a single handset that can provide for selective multimode operation.

It is currently thought that network operators, and particularly those providing services in the US are seeking to introduce the EDGE radio interface as an overlay onto existing GSM/GPRS networks. However, other operators tend to emphasise the potential importance of other technologies such as WCDMA networks.

There is a desire therefore to provide mobile communication device handsets that can support, for example, GSM/GPRS,EDGE and UMTS standards.

These three aforementioned standards, by their very nature, place particular architectural requirements upon the hardware to be introduced in accordance with the standards such that, for example, each of these three standards require different radio interfaces which, in turn, require three separate radios and related RF devices to support them.

Thus, the increase in possible modes of operation of a mobile handset nevertheless can carry disadvantages with regard to the increase in the number of components and circuits required which will lead to corresponding cost implications and disadvantageous restrictions on further miniaturization of such devices.

The present invention seeks to provide for a radio communications device, and at least a dual mode device, which can limit the potential disadvantages likely to arise from the operation of such devices.

According to the present invention there is provided a radio communications device comprising a power amplifier for delivering transmission signals to an antenna, first modulating means of a first radio technology arranged to deliver a modular signal to the power amplifier, second modulating means of a second radio technology, and routing means arranged to deliver a signal from the said second modulating means to the said power amplifier.

Through an appropriate choice of the first and second modulating means, and their respective radio technologies, the routing means advantageously allows for the use of the common amplifier by signals from both modulating means. This can advantageously serve to limit the number of power amplifiers required having regard to the plurality of possible modes of operation of the device.

Advantageously, the first and second modulating means are arranged to provide for related modulation schemes which can, for example, comprise linear modulation schemes. This relationship can also be based on the spectral efficiency of the modulation scheme.

Also the modulating means can be arranged to operate in sufficiently similar frequency bands.

In a particular embodiment, the said routing means can comprise switching means.

Yet further, the second modulating means can be arranged in accordance with a third radio technology and the said switching means then advantageously arranged to deliver the signal in accordance with the said second radio technology to the said power amplifier.

Yet further, a second power amplifier can be provided and the switch means arranged to deliver only the third radio technology to the said second power amplifier.

Preferably, the third radio technology can comprise GSM, the second radio technology can comprise EDGE and the first radio technology can comprise WCDMA.

As will be appreciated, the invention can therefore provide for an architecture for the base band of the mobile handset that supports, for example, UMTS, GSM/GPRS and EDGE and advantageously incorporates component and interface reuse and sharing so as to minimise the complexity and component count of the overall system.

The invention is described further hereinafter, by way of example only, with reference to the accompanying drawings in which: Fig. 1 is a schematic block diagram of current handset architecture; and Fig. 2 is a schematic block diagram of a handset architecture embodying the present invention.

In the illustrated example there is a requirement for the three radios; GSM, EDGE and UMTS. These differ in modulation schemes and frequencies according to Table 1 which follows and in which only handset transmission frequencies are shown.

Table 1

Standard Modulation Frequency (MHz) North America Europe (etc) I GSM/GPRS GMSK 824-849 1850-1910 890-915 1710-1785 EDGE 8PSK824-849 1850- 1910 1710-1785 WCDMA QPSK1850-1910 1920-1980 From the table it can be appreciated that EDGE can be globally deployed in the GSM/GPRS frequency band. It might therefore be expected that the same radio can be used for both. However this is not possible without changes to the power amplifier section of the radio since the modulation schemes are significantly different. That is 8PSK is a linear modulation scheme, whereas GMSK is Gaussian. This places different requirements on the transmit section of the RF circuitry. Also, GMSK is a constant envelope modulation scheme that can be amplified with high efficiency and this is the main reason for it being chosen for GSM. 8PSK is a more spectrally efficient modulation scheme, but is not so easy, or efficient, to amplify and a different form of amplifier is needed. Therefore in order to produce 8PSK modulation, a different power amplifier from that used for GMSK is reuired. It is noted that WCDMA uses QPSK, which is also a linear scheme. Thus an 8PSK power amplifier can clearly be used for QPSK, as the latter is merely a subset of the former. This is supported by the large number of dual 8PSK/QPSK products and modules - not least under IS136 where support of both modulation techniques is a requirement of the standard. Thus in the case of the dual EDGE/GSM power amplifier, the same PA can clearly be used for WCDMA. In a dual mode handset therefore there is clearly an opportunity to reduce the number of power amplifiers by combining the functions for 8PSK and QPSK.

This is possible when frequencies are similar. This advantageously reduces costs and board space. In a dual mode handset, such sharing does not prove difficult. All the control circuitry for the linear power amplifier is already present although some rerouting of signals is required, along with additional control software, but no additional components are needed.

From Table 1 above, it can be seen that there is a direct match between EDGE and WCDMA on the 1900 band used in North America. Very similar frequencies arise on EDGE 1800 and WCDMA 1900 and that are similar enough to use the same power amplifier.

On this basis, dual mode handsets in the US could share one power amplifier for EDGE and WCDMA, while European tri band handsets could share a power amplifier for EDGE 1800/1900 and WCDMA.

Fig. 1 is a diagram showing a multi mode EDGE handset as might be achieved with conventional circuitry, whereas Fig. 2 illustrates a handset employing architecture embodying the present invention and incorporating a dual-use power amplifier. It should be appreciated that the diagrams show a GSM/GPRS/EDGE 1900, WCDMA 1900 handset, as this allows the simplest illustration and is also a design that gives the greatest proportionate saving.

Turning first to Fig.1, there is provided a schematic block diagram of a handset 10 including baseband circuitry 12 from which extend control signal lines 14 - 22. These lines are arranged to deliver control signals to a WCDMA modulation section 24, a GSM/EDGE modulation section 26, a WCDMA power amplifier 28, an EDGE power amplifier 30 and a GSM power amplifier 32 as shown. Each of the power amplifiers 28 - 32 are arranged to deliver communication signals to a common antenna 34.

In addition to the control signals discussed above, the baseband circuitry 12 also provides data signals 36 to the GSM/EDGE modulation section 26 which are output as GSM or EDGE signals 38 to a switch 40 from which EDGE signals 42 are delivered to the EDGE power amplifier 30; and GSM signals 44 are delivered to the GSM power amplifier 32. Data signals 46 are also delivered from the baseband circuitry 12 to the WCDMA modulation section 24 so as to provide for WCDMA signals 48 to the WCDMA power amplifier 28.

Of course the switch 40 also receives a control signal 50 from the baseband circuitry 12. From the discussions above it will be appreciated that, due to similarities, the GSM and EDGE signals from the baseband section 12 share a modulation section 26 and the controlled switch then determines that the appropriate signals 42, 44 are delivered to the appropriate power amplifier 30, 32.

In comparison, Fig. 2 illustrates an architecture embodying the present invention. The same features as found in Fig. 1are identified by the same reference numbers.

As will be appreciated, the EDGE power amplifier of Fig. 1, along with its control and data lines, has been removed and the switch 140 arranged to deliver signals to the GSM power amplifier 32 or to the WCDMA power amplifier 28.

The configuration of Fig. 2 is based on a realisation that the WCDMA power amplifier 28 can be used also by the EDGE signals 142 and this allows for a reduction in the number of power amplifiers and control/data lines otherwise required as illustrated in comparison with Fig. 1.

Table 2. illustrates the saving in power amplifiers that can be achieved for the various radio technology combinations

Table 2

GSM/GPRS/EDGE WCDMA PAs PAs PAs band(s) band(s) previously now saved 1900 1900 3 2 1 850/1900 1900 5 4 1 900/1800/1900 1950 1 900/1800/1900 1900/1950 1 Although it might be considered that a potential problem with the dual use power amplifier is that the power output of a WCDMA power amplifier is generally less than those for GSM, it is noted that this is also true of the available range of EDGE amplifiers. Provision has been made in the EDGE signalling message to allow a handset to have a lower power output in EDGE that in GSM, so it is clearly expected that handsets will behave in this way. So while a handset with a dual use PA may give less power, this will not prove problematic as far as the network is concerned.

Although it is appreciated that the manufacture of dual purpose GSM/EDGE power amplifiers is planned, the availability of such components will not reduce the effectiveness of the present invention, particularly since the invention is directed to aspects of architecture rather than the power amplifier itself. Indeed, it is considered that the availability of such dual-purpose devices will further enhance and emphasize the advantages offered by the present invention. For example there would only then be a need for one power amplifier for each waveband and the same power amplifier could be used for all of the three technologies noted above in Table 2.

The values would then appear as follows in Table 3.

Table 3

G S M/G P R S/E D G. E WC D MA PAs PAs PAs band(s) band(s) assuming Now saved dual EDGE/GSM 1900 1900 2 1 1 850/1900 1900 2 1 900/1800/1900 1950 2 1 900/1800/1900 1900/1950 2 1 Although the same number of power amplifiers are saved, the basic number of power amplifiers from which the reduction is achieved is less and so the percentage saving, and related improvement in efficiency, is correspondingly greater.

Claims

Claims 1. A radio communications device comprising a power amplifier for

delivering transmission signals to an antenna, first modulating means of a first radio technology arranged to deliver a modular signal to the power amplifier, second modulating means of a second radio technology, and routing means arranged to deliver a signal from the said second modulating means to the said power amplifier.

2. A device as claimed in claim 1, wherein the first and second modulating means are arranged to provide for related modulation schemes.

3. A device as claimed in claim 2, wherein the said relationship is such that the schemes comprise linear modulation schemes.

4. A device as claimed in claim 2, wherein the said relationship is based on spectral efficiency.

5. A device as claimed in any one or more of claims 1 to 4, wherein the modulation means are arranged to operate in similar frequency bands.

6. A device as claimed in any one or more of the preceding claims, wherein the said routing means comprises switching means.

7. A device as claimed in any one or more of the preceding claims, wherein the second modulating means is arranged in accordance with a third radio technology and the said switching means is arranged to deliver the signal in accordance with the said second radio technology to the said power amplifier.

Amendment to the claims have been filed as follows Claims 1. A radio communications device comprising a power amplifier for delivering transmission signals to an antenna, first modulating means of a first radio technology arranged to deliver a modular signal to the power amplifier, second modulating means of a second radio technology, and routing means arranged to deliver a signal from the said second modulating means to the said power amplifier, wherein the first and second modulating means are arranged to provide for related modulation schemes, and wherein the said relationship is such that the schemes comprise linear modulation schemes.
2 A device as claimed in claim 1, wherein the said relationship is based on spectral efficiency.
3. A device as claimed in claim 1 or 2, wherein the modulation means are arranged to operate in similar frequency bands.
4. A device as claimed in any one or more of the preceding claims, wherein the said routing means comprises switching means.
5. A device as claimed in any one or more of the preceding claims, wherein the second modulating means is arranged in accordance with a third radio technology and the said switching means is arranged to deliver the signal in accordance with the said second radio technology to the said power amplifier.
6. A device as claimed in claim 5 and including a second power amplifier and wherein the switch means arranged to deliver only the third radio technology to the said second power amplifier. 1'
7. A device as claimed in claim 5 or 6, wherein the third radio technology comprises GSM, the second radio technology comprises EDGE and the first radio technology can comprise WCDMA.

8. A radio communications device substantially as herein before described with reference to and as illustrated in Fig 2 of the accompanying drawings. i

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8. A device as claimed in claim 7 and including a second power amplifier and wherein the switch means arranged to deliver only the third radio technology to the said second power amplifier.
9. A device as claimed in claim 7 or 8, wherein the third radio technology comprises GSM, the second radio technology comprises EDGE and the first radio technology can comprise WCDMA.
10. A radio communications device substantially as herein before described with reference to and as illustrated in Fig 2 of the accompanying drawings.