WO2015166136A1

WO2015166136A1 - A multiple radio device with reduced cross-interference

Info

Publication number: WO2015166136A1
Application number: PCT/FI2015/050271
Authority: WO
Inventors: Timo Hakala
Original assignee: Nokia Inc
Current assignee: Nokia Inc
Priority date: 2014-04-30
Filing date: 2015-04-21
Publication date: 2015-11-05
Anticipated expiration: 2016-10-30

Abstract

A device comprising a plurality of radios each of which has multiple of co-banded transmitters of which any one can be selectively enabled at any time with at least one of the transmitters having its output coupled to a co-ex filter and at least one other of the transmitters having its output coupled to a non-co-ex filter, a radio antenna associated with each said radio, a selection mechanism capable of selectively coupling each said radio antenna to the output of any one of the co-ex/non-co-ex filters, a detector capable of identifying a temporal overlap of a transmission in at least one of the radios with a reception in one or more other radios, and a ontroller capable of selectively enabling each said temporally overlapping transmission through a transmitter having a co-ex filter coupled to its output, while simultaneously coupling the corresponding radio antenna to the output of the co-ex filter of the selectively enabled transmitter.

Description

A MULTIPLE RADIO DEVICE WITH REDUCED CROSS-INTERFERENCE

FIELD OF THE INVENTION

This invention relates to the field of devices incorporating radios. In particular, it relates to devices having a plurality of radios.

BACKGROUND OF THE INVENTION

Several modern devices incorporate multiple radios in order to provide the user with the capability of multiple wireless connections. A dual-SIM mobile phone is one such device available today, in which each of the SIMs corresponds to a separate connection - i.e. separate mobile phone numbers. The individual SIMs (and therefore the corresponding connection) may even correspond to separate mobile networks - i.e. subscribe to a different Network Service Providers. Mobile phones with three or even more SIMs are also known. While the most common use of multiple radio transmitters relates to mobile phones it is also applied to other devices such as laptops, tablets with 3G + WLAN capability, "Phablets" (Phone + Tablet), and similar other devices.

Multiple SIM mobile stations, of which mobile phones are a part, are of 2 basic types: "Standby Multiple SIM" and "Active Multiple SIM". In the former, all the connections in the phone are accessible from the mobile network only as long as none of the connections is active (i.e. all the connections available in the mobile station are in "Standby" mode), however the moment one of the connections becomes "active" all the remaining connections become inaccessible from all mobile networks. This limitation results from the fact that the mobile station comprises a single radio which becomes dedicated to the active connection and is therefore not available for any of the other connections for the duration of the active "call".

In "Active Multiple SIM" mobile stations on the other hand, each connection has a dedicated radio available to it, and therefore all the connections can be "active" simultaneously. It is also possible to switch between network connections utilizing different SIMs without disconnecting any prior active connection. The multiple-active radio feature of modern day devices is implemented in the context of a significant variety of technologies in use today. For instance, in the case of mobile devices 2G-GSM technology is in simultaneous use with the more modern 3G-WCDMA and 4G technologies of the same technology family. Since the deployment status of these technologies varies over time and from place to place the mobile network comprises a heterogeneous mixture of technologies within the same family. In order to remain compatible with all the different technologies in use in the network, modem day devices therefore incorporate multiple sets of transmitters and receivers (each transmitter-receiver set is termed a "transceiver"), each corresponding to the appropriate technology. Each transceiver is selectively enabled as needed - for instance, the radio of a 3G capable mobile phone may include both a 2G-GSM transceiver as well as a 3G-WCDMA transceiver. When the mobile station is connected to a 2G-GSM network station the 2G-GSM transceiver is selectively enabled. Alternatively, when the same mobile station is connected to a 3G- WCDMA network station the 2G-GSM transceiver is deselected and the 3G-WCDMA transceiver is selected.

In order to obtain long range operation the output power of a transmitter is boosted by a Power Amplifier which is connected to the output of the transmitter section of a transceiver. Each power amplifier in turn has a transmit filter coupled to its output and the antenna of the corresponding radio couples to the output of this filter during the transmit state of the radio. Similarly the same antenna couples to a receive filter which is connected to the input of the receiver section of the transceiver during the receive state of the radio. The transmit and receive filter designs and performance vary in accordance with the technology of the transceiver. Thus, the transmit filter of a 2G-GSM power amplifier is distinct from the transmit filter of a 3G-WCDMA transmit power amplifier.

In many applications some or all of the radios in a device operate in the same frequency band - a condition which is termed as ^Mco-banding" in the context of this specification. This simultaneous operation of co-banded radios gives rise to potential cross-interference between them owing to the close physical proximity of the radios and their associated antennas - a condition that is aggravated by the continuous trend towards miniaturization in all electronic devices and particularly in telecommunication devices. The power output of the transmitting radio is kept relatively high by using a transmitter power amplifiers (in order to obtain adequate range) while the sensitivity of a radio in receive mode Is designed to accept signals at very low power levels for the same reason (achieving good range). The high power signals from a co-banded transmitting radio antenna located in close physical proximity can easily mask out the weak signals from a distant radio when the transmission state of one active radio overlaps with the receive state of another active radio in the same device.

An important aspect of the performance of transmit and receive filters relates to the cross- interference suppression capability of co-banded radios which are close physical proximity - i.e. a critical feature in the multiple active radio context. Those filters which provide adequate suppression of cross-interference in these conditions are termed ^uco-ex" filters (i.e. co-existence enabling filters) while those filters which are unable to provide sufficient cross-interference suppression are termed non-co-ex filters (i.e. filters incapable of permitting co-existence of proximal co-banded radios). The conventional transmit filter at the output of a 3G-WCDMA power amplifier is an example of a "co-ex" filter while the conventional transmit filter at the output of a 2G-GSM power amplifier is an example of a "non-co-ex" filter.

Figure- 1 shows a traditional architecture of a dual-active-SIM mobile station comprising two radios (1.01) and (1.10) - one corresponding to each SIM. Each radio incorporates two transmitters, one of which is a 2G-GSM transmitter - (1.02) for radio (1.01) and (1.11) for radio (1.10) - while the other is a 3G-WCDMA transmitter - (1.03) for radio (1.01) and (1.12) for radio (1.10). Each 2G-GSM transmitter is connected to the input of a 2G-GSM power amplifier - (1.04) for transmitter (1.02) and (1.13) for transmitter (1.11). Each 2G- GSM power amplifier in turn has a low-pass 2G-GSM filter - (1.06) for GSM power amplifier (1.04) and (1.15) for 2G-GSM power amplifier (1.13) - at its output Similarly, each 3G- WCDMA transmitter is connected to the input of a 3G-WCDMA power amplifier - 3G-WCDMA transmitter (1.03) is connected to 3G-WCDMA power amplifier (1.05) and 3G-WCDMA transmitter (1.12) is connected to 3G-WCDMA power amplifier (1.14). Each 3G-WCDMA power amplifier is, in turn, connected to the Tx port of a duplex filter - (1.07) for 3G- WCDMA power amplifier (1.05) and filter (1.16) for 3G-WCDMA power amplifier (1.14) - while the Rx port of the duplex filter connects to the input of the corresponding 3G-WCDMA receiver. A selection mechanism - (1.08) for radio (1.01) and (1.17) for radio (1.10) - connects each antenna - (1.09) for radio (1.01) and (1.18) for radio (1.10) - to the output of the corresponding low-pass 2G-GSM filter or the antenna port of the duplex 3G-WCDMA filter. This architecture experiences significant cross-interference under dual-active-SIM conditions.

This problem of the architecture of figure-1 is explained in figure-2 where GSM SIM 1 represents the operation of radio 1 and GSM SIM 2 represents the operation of radio 2 in relation to the time slots during which they either transmit or receive signals. The interference occurs during those time slots in which one radio is in transmit mode while the other radio is in receive mode at the same time (2.1) overlapping with (2.2), or (2.3) overlapping with (2.4), or (2.5) overlapping with (2.6) as shown. The overlapping transmission and reception result in desensitization of the radio which is in the receive mode by a factor of as much as 30db. This may result in a dropped call. In such conventional multiple SIM active mobile stations, the cross-interference problem is not addressed at all and the associated call drops are accepted as unavoidable. Figure-3 illustrates one elementary solution to the problem for the case of a dual-active- SIM. Each 2G-GSM power amplifier is provided with an additional co-ex filter (3.08) in Radio- 1 and (3.19) in Radio-2 along with additional selection mechanism (3.06) in Radio-i and (3.17) in Radio-2, which enable the selective use of the co-ex filter during a dual-active- SIM condition. However, this arrangement involves increased cost and space and is therefore unacceptable for many applications. Also, since the additional co-ex filter is used only when multiple radios are used simultaneously, there is inefficient utilization of resources.

WO 2013/007869 relates to an apparatus comprising of multiple SIM card connectors in a communication system configured to operate according to multiple communication protocols and coupled to at least one processor (610) for processing communication signals, a control unit (632) configured to generate a control signal to select a communication path (629-1, 629-2, 631-1, 631-2, 645-1, 647-1, 647-2) dedicated to an associated SIM card connector, and a switch (630) responsive to the control signal to switch the communication signals received from or transmitted to any one of the multiple SIM card connectors using the selected communication path. An apparatus comprises multiple radio frequency integrated circuit RFICs (640-1, 640-2) coupled to a plurality of RF interfaces of a digital baseband (600) of a communication apparatus, the multiple RFICs include a programmable state machine that executes programmed instructions to perform write to the RFICs, thereby enabling RF control.

WO 2013/150171 discloses coupling radio modems (22, 24) to antennas (40, 42) in a radio apparatus. In an embodiment, a first antenna (40) of the radio apparatus is coupled to a first signal line connecting the first antenna (40) to a first radio transmitter (22) of the radio apparatus; a second antenna (42) of the radio apparatus is coupled to a first signal interface (32) of a second radio transmitter (24) via a second signal line; and, simultaneously with coupling the first antenna (40) to the first signal line, the first antenna (40) is coupled to a third signal line connecting the first antenna (40) to a second signal interface (30) of the second radio modem (24)

SUMMARY OF THE INVENTION In order to address the aforementioned drawbacks of conventional systems, the present invention provides a solution in which, wherever possible, cross-interference between multiple active co-banded radios is avoided without any additional hardware elements, by improved utilization of the existing resources. The present invention provides a device which comprises a plurality of radios each of which has a plurality of co-banded transmitters of which any one can be selectively enabled at any time with at least one of the transmitters having its output coupled to a co-ex filter and at least one other of the transmitters having its output coupled to a non-co-ex filter, a radio antenna associated with each radio, a selection mechanism for selectively coupling each radio antenna to the output of any one of the co-ex/non-co-ex filters; a detector capable of identifying a temporal overlap of a transmission in at least one of the radios with a reception in one or more other radios and a controller capable of selectively enabling each said temporally overlapping transmission through a transmitter of said radio having a co-ex filter coupled to its output, while simultaneously coupling the corresponding radio antenna to the output of the co-ex filter of the selectively enabled transmitter.

The present invention also provides a method of controlling a mobile station having multiple radios each of which contains a plurality of selectable transmitters comprising the steps of detecting simultaneous operation of a plurality of co-banded said radios and selectively coupling the radio antenna of each active radio having a transmission overlap with reception in another radio to a transmitter incorporating co-ex filtering.

The present invention also provides a mobile station having multiple radios each of which contains multiple selectable transmitters with means for detecting simultaneous operation of a plurality of said radios and means for selectively coupling the radio antenna of each active radio which has a transmission overlapping with the reception of a co-banded radio, to a transmitter incorporating co-ex filtering. The present invention also covers a controller for a device comprising a plurality of radios each of which contains a plurality of individually selectable co-banded transmitters each having its output coupled to a transmit filter with at least one of the transmit filters being a co-ex filter, in which the controller selectively enables only those transmitters that have co-ex transmit filters while at the same time coupling a radio antenna associated with the corresponding radio to the output of the enabled co-ex transmit filter in those radios in which it detects a temporal overlap with a reception in one or more other co-banded radios.

BRIEF DESCRIPTION OF THE DRAWINGS: The invention will now be described with reference to the accompanying figures. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears.

« FIGURE 1 shows a conventional dual active SIM mobile station architecture.

■ FIGURE 2 shows the problem associated with the operation of dual active SIM mobile station according to the prior art.

« FIGURE 3 shows a direct (conventional) implementation which solves the problem addressed by the invention.

■ FIGURE 4 shows a general multiple transmitter architecture according to the invention.

■ FIGURE 5 shows an embodiment incorporating the invention.

^■ FIGURE 6 shows a flowchart depicting the operation of the invention. DETAILED DESCRIPTION OF THE DRAWINGS:

The embodiments described and illustrated in the figures are presented by way of example only and are not intended as a limitation upon the concepts and principles of the present invention. As such, it will be appreciated by one having ordinary skill in the art that various changes in the elements and their configuration and arrangement are possible without departing from the spirit and scope of the present invention as set forth in the appended claims. Figure-1 has been explained in the background to the invention. Figure-2 has also been described in the background to the invention. Figure-3 has similarly been explained in the background to the invention.

Figure-4 shows a block diagram of a generic implementation of the radio section of a device incorporating the present invention. The device incorporates "m" radios identified as "Radio 1" (4.1) to "Radio m" (4.43), some or all of which may be co-banded. Each radio comprises "n" transceivers identified as 'Transceiver 1.1" (4.02) to "Transceiver l.n" (4.15) for "Radio 1" (4.01), as "Transceiver 2.1" (4.23) to "Transceiver 2.n" (4.36) for "Radio 2" (4.22) and so on until "Transceiver m.l" (4.44) to "Transceiver m.n" (4.57) for "Radio m" (4.43). Each radio has an associated radio antenna identified as "Antenna 1" (4.21) to "Antenna m"

(4.63) . Each transceiver also has a corresponding filter-set at its output/input. The transceivers within each radio comprise a mix of filter types - i.e. some which support "co- existence" of physically co-located adjacent channels (i.e. "Co-ex" filters), while other transceivers within the same set have filters which do not support physical co-location (i.e. non-Co-ex filters). The output/input of any one of the transceivers in each radio transmitter can be selectively coupled to the radio antenna associated with that radio. A single controller

(4.64) determines the transceiver selection for each active radio, such that whenever multiple radios are active and the transmission of one or more radios overlaps in time with a receive function in one or more other active radios only a transmitter having a Co-ex filter at its output is enabled in each transmitting radio while at the same time its radio antenna is selectively coupled to the output of the co-ex filter at the output of the enabled transmitter. Figure-5 shows an embodiment of a device incorporating the invention. It is a generalized figure of a Dual-active SIM phone. This phone comprises two co-banded radios (5.01) and (5.10) - one corresponding to each SIM, each of which has two transmitters one of which is a 2G-GSM transmitter ~ (5.02) in Radio-1 (5.01) and (5.11) In Radio-2 (5.10), while the other is a 3G-WCDMA transmitter ~ (5.03) in Radio-1 (5.01) and (5.12) in Radio-2 (5.10). The 2G-GSM is connected to a GSM power amplifier having a low-pass GSM filter at its output. The 3G-WCDMA transmitter is connected to a 3G-CDMA power amplifier having one section of a duplex filter at its output while the second section of the duplex filter connects to the 3G receiver. A selection mechanism - (5.08) in Radio-1 and (5.17) in Radio-2 - connects either the output of the low pass 2G-GSM filter or the duplex 3G-WCDMA filter to the antenna of the Radio-l(5.01). A single common controller (5.19) selectively enables either one of the transmitters in each radio and also controls both the selection switches. It determines the selection in a manner that whenever both the radios are active and one radio is in a transmit state while the other is at the same time in a receive state only a transmitter having a Co-ex filter at its output is selectively coupled to the radio antenna in the radio which is in the transmit state.

Figure-6 shows a flowchart depicting the operation of the invention in a device which incorporates multiple radios at least some of which are capable of operating simultaneously. The activity begins by continuous monitoring of the active state of each radio (6.1). If multiple radios are found to be simultaneously active, the status of each active radio which is in transmit mode (6.2) as well as each active radio in receive mode (6.3) is checked for a possible temporal overlap with any of the other radio which are in receive mode (6.4). If an overlap is detected, then it is determined whether the transmitter involved in the overlap has a co-ex filter coupled to its output (6.5). If the transmitter does have a co-ex filter, then there is no interference and no action is required. However, if the filter coupled to the output of the transmitter is a non-co-ex filter, then another transmitter which has co-ex filtering is selected (6.6) and the transmissions are then routed through it (6.7).

The present invention was described in part above with reference to flowchart illustrations and/or block diagrams of methods and apparatus, according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and/or block diagrams, and combinations of blocks in the flowchart illustrations and/or block diagrams, can also be implemented by computer program instructions in certain embodiments.

The flowchart and schematic diagrams illustrate the architecture, functionality, and operations of some embodiments of methods, systems, and computer program products according to the invention. Each block may represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical functions). It should also be noted that in other implementations, the function(s) noted in the blocks may occur out of the order noted in the figures. For example, two blocks shown in succession may in fact, be executed substantially concurrently or the blocks may sometimes be executed in reverse order depending on the functionality involved.

Only exemplary embodiments of the invention have been disclosed in the drawings and description and the scope of the invention is defined only by the following claims.

Claims

We datm:

1. A device comprising:

- a plurality of radios;

- each said radio having a plurality of individually selectable co-banded transmitters;

- each said transmitter having its output coupled to a transmit filter;

- at least one of said transmit filters being a co-ex filter;

- a radio antenna associated with each said radio;

- a selection mechanism capable of selectively coupling said radio antenna to the output of any one of said transmit filters; and

- a detector capable of identifying a temporal overlap of a transmission in at least one of said radios with a reception in one or more other said radios,

- a controller capable of selectively enabling each said temporally overlapping transmission through a transmitter of said radio having a co-ex filter coupled to its output, while simultaneously coupling the corresponding radio antenna to the output of the co-ex filter of the selectively enabled transmitter.

2. A device as claimed in claim 1, comprising two radios.

3. A device as claimed in any of the preceding claims, wherein at least one radio comprises a 2G-GSM transmitter.

4. A device as claimed in any of the preceding daims, wherein at least one radio comprises at least one of a 2G-GSM receiver, a 3GWCDMA receiver, an LTE receiver, a WLA receiver, a Bluetooth receiver or a GPS receiver.

5. A method of controlling a device containing multiple co-banded radios each of which incorporates a plurality of transmitters with at least one of said transmitters utilizing co-ex filtering, comprising the steps of:

- identifying whether a plurality of said radios are active;

- detecting a temporal overlap of a transmission in one or more active radios with a reception in one or more other active other co-banded radios; and - enabling the temporally overlapping transmissions through transmitters which utilize co-ex filtering.

6. A method as claimed in claim 5, comprising of two co-banded radios.

7. A method as claimed in claim 5, wherein routing the temporally overlapping transmissions comprises the step of routing 2G-GSM transmissions through a co- banded 3G-WCDMA transmitter.

8. A device containing multiple co-banded radios each of which incorporates a plurality of transmitters with at least one of said transmitters utilizing co-ex filtering, said device comprising:

- means for determining whether a plurality of said radios are active;

- means for detecting a temporal overlap of a transmission in one or more active radios with a reception in one or more other active radios; and

- means for routing the temporally overlapping transmissions through transmitters which incorporate co-ex filtering.

9. A device as claimed in claim 8, comprising of two radios.

10. A device as claimed in claim 8, wherein routing the temporally overlapping transmissions comprises the step of routing 2G-GSM transmissions through a co- banded 3G-WCDMA transceiver.

11. A controller for a device comprising:

- a plurality of radios;

- each said transmitter having its output coupled to a transmit filter;

- at least one of said transmit filters being a co-ex filter;

- a radio antenna associated with each said radio;

said controller being capable of enabling each said temporally overlapping transmission through a selected one of said transmitters of said radio having a co- ex filter coupled to its output, white simultaneously coupling the corresponding radio antenna to the output of the co-ex filter of the selectively enabled transmitter.