GB2492122A

GB2492122A - Diversity antenna system with de-correlation apparatus and method

Info

Publication number: GB2492122A
Application number: GB1110562.4A
Authority: GB
Inventors: Seppo Rousu; Hannu Palomaa; Andrew Frankton
Original assignee: Renesas Mobile Corp
Current assignee: Renesas Electronics Corp
Priority date: 2011-06-22
Filing date: 2011-06-22
Publication date: 2012-12-26
Also published as: GB201110562D0

Abstract

A radio communication apparatus, or method, comprises: a plurality of antenna elements, where the signal of an antenna element does not readily correlate with that of another antenna element. A phase shift between antenna radiation phase patterns may be provided. The said patterns may be associated with antenna elements which are simultaneously receiving and/or transmitting radio frequency signals via an air interface. The phase shift may be introduced in order to obtain orthogonality between the associate radio frequency signals. The phase shift may be provided by: the design of the antenna elements, electrical tuning of the antenna elements or by changing galvanic characteristics, possibly using switches, of one or more of the antenna elements. Signal feedback may be used in controlling the phase shift adjustments. The phase shift may be substantially 180 degrees. An antenna element may be replaced by another element based on various operational characteristics. A memory storing antenna configurations and tuning data may be used in obtaining a phase shift. A computer program product may be provided to execute the above radio communication method.

Description

Antenna Arrangement

Field of the Invention

The invention relates generally to communication systems. More particu-larly, the invention relates to an antenna arrangement for increasing reception and/or transmission diversity in radio a communications system.

Background of the Invention

In telecommunications, a diversity scheme refers to a method for improv-ing the reliability of a communication by using two or more communication channels with different characteristics. Diversity plays an important role in combatting fading and co-channel interference and avoiding error bursts. It is based on the fact that indi-vidual channels experience different levels of fading and interference. It is known to use either a transmit diversity scheme or a receive diversity scheme. In the transmit diversity scheme, a signal is transmitted via multiple communication channels over an air interface, and, in the receive diversity scheme, a signal is received via multiple communication channels over the air interface. Therefore, muhiple versions of the same signal may be transmitted and/or received and combined in the receiver(s) sys-tem(s) typically having analog and digital functionalities and requisite software (SW) algorithms and functionality for fulfilling the system's requirements. Diversity tech-niques may exploit so-called muhipath propagation, resulting in a diversity gain.

In radio communication networks, such as for example in the evolved high speed packet access (HSPA+), in the long term evolution (LTE), in the LTE-Advanced (LTE-A) of the 3rd Generation Partnership Project (3GPP), in the code division mul- tiple access (CDMA) and in the time division synchronous CDMA (TD-SCDMA) sys-tems, a multiple-input and multiple-output (MIMO) technique may be used. In the MIMO, multiple antennas at both the transmitter and receiver are employed to improve the communication performance. The MIMO may be applied in generating transmit and/or receive diversity in network elements and terminals. Furthermore, the MIMO may be applied in increasing data/payload throughput of the system (MIMO gainlperformance) as the need of retransmissions may be minimized. Further, different signals may be transmitted simultaneously in different data streams. However, in order to obtain increased reliability or throughput, low correlation between the applied MI- MO antennas is required. Thus, it is important to provide a solution for efficiently us-ing the diversity schemes with multiple antennas.

S Brief description of the invention

Embodiments of the invention seek to improve MIMO/diversity perfor-mance when applying multiple antennas.

According to an aspect of the invention, there is provided a method as spe-cified in claim 1.

According to an aspect of the invention, there are provided apparatuses as specified in claims 13 and 25.

According to an aspect of the invention, there is provided a computer pro-gram product as specified in claim 26.

According to an aspect, there is provided a computer-readable distribution medium carrying the above-mentioned computer program product.

According to an aspect of the invention, there is provided an apparatus comprising means for performing any of the embodiments as described in the ap-pended claims.

Other aspects and embodiments of the invention will become apparent

from the following description and claims.

Brief Description of the Drawings

In the following, the invention will be described in greater detail with ref-erence to the embodiments and the accompanying drawings, in which Figure 1 is a block diagram presenting a MIMO communication according to an embodiment; Figures 2A and 2B are schematic diagrams illustrating antenna radiation phase pattems according to some embodiments; Figures 3 and 4 are block diagrams illustrating circuits for fixing and/or tuning the antenna characteristics according to some embodiments; Figure 5 and 6 are flow diagrams illustrating methods according to some embodiments; Figure 7 is a block diagram of an apparatus according to an embodiment; Figure 8 is a graph depicting an envelope correlation coefficient according to an embodiment; Figure 9 is a block diagram depicting an embodiment with off-ground an-tennas; and Figure 10 is a block diagram illustrating tuning of a ground signal connec-tion according to an embodiment.

Summary of the Invention

The following embodiments are exemplary. Although the specification may refer to "an", "one", or "some" embodiment(s) in several locations of the text, this does not necessarily mean that each reference is made to the same embodiment(s), or that a particular feature only applies to a single embodiment. Single features of differ- ent embodiments may also be combined to provide other embodiments. Radio com- munication networks, such as the HSPA+, the Long Term Evolution (LTE), the LTE-Advanced (LTE-A) of the 3 Generation Partnership Project (3GPP), the CDMA, or the TD-SCDMA, are typically composed of at least one base station (also called a base transceiver station, a radio network controller, a Node B, or an evolved Node B, for example), at least one user equipment (UE), such as a mobile user terminal, a palm computer, personal computer/convergence devices, a gaming device, consumer elec-tronics, automotive communicationlinfotainment connected cars, a smart book, a data card, feature & basic phones, femtocell, relay, router, or any other apparatus capable of operating in a mobile communication network, in a device to device network, in a ma- chine to machine network, and optional network elements that provide the interconnec-tion towards the core network. The UE may also be called a user terminal, terminal device, a modem, or a mobile station, for example. The base station connects the UEs via the so-called radio interface to the network. The base station may provide radio coverage to a cell, control radio resource allocation, handle frequency and bandwidth allocation, handle modulations, determined the number of data streams and/or number of carriers, handle interoperability related functionalities, perform data/payload and control signaling, etc. The cell may be a macrocell, a microcell, femtocell, ad hoc net-work or any other type of cell where radio connection(s)/coverage is present between devices. Radio communication may be also between device to device (D2D, E2E) or machine to machine, electrical home equipment, etc. Radio communication may hap- pen for different needs, data/payload delivery, supervision information, safety informa- tion, entertainment information, services, location, locationlnavigation services, gam-ing, transportation services, entertainment services, as some examples.

In general, a base station may be configured to provide communication services according to at least one of the following radio access technologies (RATs): Worldwide Interoperability for Microwave Access (WiMAX), 802.1 in, Global System for Mobile communications (GSM, 2G), GSM EDGE radio access Network (GE-RAN), General Packet Radio Service (GRPS), Universal Mobile Telecommunication System (UMTS, 3G) based on basic wideband-code division muhiple access (W-CDMA), high-speed packet access (HSPA, HSPA+), LTE, CDMA, TD-SCDMA and/or LTE-A, for example. The present embodiments are not, however, limited to these protocols, they may be used in different time division duplexing (TDD) and fre-quency division duplexing (FDD) systems and combinations of those. In the terminal, a (universal) subscriber identity module(s) (SIM/USIM) may be needed for network connections and services. Each radio access operator may require own SIM/USIM or all radio access may be covered by one. Typically the SIM/IJSIM is implemented on a SIM/USIM card containing special purpose information and having memory for desig-nated features. In alternative embodiments SIM/USIM may be also implemented in the device, modem, terminal hardware (HW) and/or in a special purpose SW of the ter- minal. In standardized or ad-hoc systems a device may be a slave or a master accord- ing to handshaking. The UE device may be controlled, for example, at least by key-board, touch display, voice, external commands from air interface, external commands from galvanic interfaces, or it may be independent, for example. The UE may be de-signed to execute commands steps sequentially and/or concurrently.

As already indicated, the base station may be a node B (NB) as in the LTE, an evolved node B (eNB) as in the LTE-A, a radio network controller (RNC) as in the UMTS, a base station controller (BSC) as in the GSM/GERAN, a relay node, a router node femtocell node, picocell node or any other apparatus capable of controlling radio communication and managing radio resources, interoperability, and interferences with-in the cell, between adjacent cells and between alternative cells, for example. This may take place also between different communication systems. The base station may also have an effect on mobility management by controlling and analyzing radio signal lev-el-measurements performed, quality of service (QoS), throughput, bit error rate, block error rate, acknowledgement (ACK)/negative ACK (NACK) rated by a user terminal, carrying out its own measurements and performing handovers of user terminals.

Conventional and low cost transceivers may have only a single antenna. In contrast, devices with multiple antennas may employ diversity reception and/or trans-mission or MIMO reception and/or transmission, where at least one second antenna is needed for achieving the MIMO/diversity functionality. The MIMO gain refers to in- creased data/payload throughput, for example. Alternatively, a single-input multiple- output (SIMO) or a multiple-input single-output (MISO) system may be used, depend-ing on whether diversity reception or transmission is to take place. Antenna systems may be built with different combinations: some antennas may have only transmission (Tx) functionality, some may have only reception (Rx) functionality, and some may be employed with both the Tx and the Rx functionalities. That is, the needed Tx and Rx functionalities may be implemented with different antennas or one antenna may per-form both functionalities wherein the functionality may be switched in use with special purpose control signals. In Tx functionality, a dedicated Tx antenna may convey sig-nals from a transceiver to the air interface. In Rx functionality, an RX antenna may convey reception signal(s) from the air interface to the transceiver. A user terminal may contain several antennas and each antenna's functionality may be altered in time domain for improved correlation between antennas, interoperability between commu-nication systems, terminal use case, according running applications, total radiated power (TRP), total isotropic power (TIS), power consumption, data class, active com-munication systems, running services, and/or user defined performance level.

As indicated, MIMO, SIMO or MISO technology may be of use when ap-plying diversity transmission or reception. MIMO has attracted attention in wireless communications, because it can offer significant increases in data throughput and link range with equal additional bandwidth or transmit power. It achieves these by applying a higher spectral efficiency (more bits per second per hertz per bandwidth) or diversity (reduced fading). Because of these properties, MIMO plays an important role in mod-em wireless communication standards such as in the IEEE 802.1 in (WIFI), in the 4G, in the 3GPP LTE, in the worldwide interoperability for microwave access (WiMAX) and in the evolved high speed packet access (HSPA+) and in other evolutions. The HSPAILTE radio communication frequencies are defined in 3GPP standards. In cur- rent standards, the lowest frequency bands start from 700 MHz and the highest fre- quencies are at 2.6 GHz frequency range. Furthermore, different FDD/TDD band allo-cations are also given an identification number from 1 to 41. However, in future, even higher and/or lower frequencies may be used. As an example, 3.5 GHz is under stan-dardization for TDD/FDD systems. Wireless LAN is in use in the industrial, scientific and medical (ISM) band, at S GHz and 60 GHz range. Indeed, communication systems may use different coding schemes, time domain activity, frequency domain activity, number of carriers, carrier aggregation, modulations, bandwidth, combinations in the transmissionlreception activity.

Commercially, within the bands in question, relatively low frequencies are most interesting for network operators, because lower frequency radio waves are able to travel longer distances than radio waves at higher frequencies. Figure 1 shows an exemplary MIMO communication scheme, where the eNB 100 of the LTE applies four antennas 102 to 108 and the UE 110 is equipped with two antennas 112 to 114. Then communication may take place via multiple communication channels as shown with solid lines between the antennas. The MIMO may thus be related to data transmission in uplink and/or downlink directions.

A single antenna may be operational with one communication system or it may be shared with multiple communication systems using the same frequency alloca-tion or multiple communication systems at a designed antenna frequency range. The UE support for communication system frequencies may be done with multiple anten-nas at different frequency ranges, for example about 1 GHz, about 1.5 GHz, about 2 GHz, about 2.6 GHz, and about 3.5 GHz, as examples of radio communication fre-quency ranges. In general, the accurate frequencies and channel numbering are detailed in standards. In some embodiments only certain frequency ranges may be handled by one antenna.. In other embodiments all needed frequency ranges may be handled by the same antenna. Further, the MIMO/diversity functionality transmissionlreception, dual active radio operation with single/dual SIM/USIM, carrier aggregation, and other radios may share the antennas available. In an embodiment, a multiple antenna struc- ture may become a single antenna structure having equal special purpose functionali-ties, characteristics and performance as the muhiple antenna structure. Moreover, when antenna radiated frequency is decreased e.g. to 1 GHz and below, also a printed wiring board (PWB) of the terminal device (UE) may be acting as a radiator in addition to the antenna radiator, and thus influence the antenna performance parameters and characte-ristics. Accordingly, the terminal PWB dimensions may be partly defined according to, for example, radiation frequencies and bandwidth needed in terminals. Antenna im- plementation challenges are related to increasing the number of frequency bands, in- cluding lower frequencies of operation, having multiple antennas as required for MI- MO and diversity, decreasing antenna volume, distortion products, port-to-port isola-tion, and imbalance between the antennas, for example. This is because, for example, UE displays are getting larger, the UE user interfaces cover larger area of the terminal, and the form factors are getting thinner.

The MIMO reception performance may be measured with a data through-put. However, a low signal correlation is needed to capture the full potential of the diversity/MIMO schemes. In order to obtain measurable gain in the data throughput by a radio modem responsible of combining the received signals from multiple antennas, the signals received by the different reception antennas need to be mutually uncorre-lated or close to uncorrelated (i.e. having a relatively low correlation). In other words, the signals received by different antennas need to be mutually orthogonal. It should be noted here that, for the signals to be orthogonal, the signals do not need to be totally uncorrelated. It is sufficient that the receiver may apply the orthogonality between the signals in order to increase the signal reception reliability. That is, for signal reception, the orthogonality means that the received signals may vary substantially independently of each other during observation time. However, an antenna arrangement that may result in the desired correlation level (orthogonality) is related to the radio frequencies in use.

Further, the antennas may share a common sub-wavelength counterpoise (for example, the PCB and the attached conductor components) so the ability to make the antennas independent may be limited. Additionally, the common counterpoise may limit the isolation between antennas. To facilitate spatial separation and exploit the best locations in the terminallUE/device, placing the RF front-end sections in more than one area of the handset may be needed. With multiple antennas, some of the an- tennas may be relegated to less optimal positions where hand effects may be more pro-nounced. Band-tuning may be used to reduce the physical size of an antenna without reducing the efficiency.

The MIMO reception may apply space diversity due to the spaced antennas according to MIMO. Therefore, the separation between the antennas with respect to the wavelength affects the correlation between the signals received/transmitted at the multiple antennas. From this it is clear that the antenna arrangement difficulty increas-es when radio communication frequency decreases. Especially for frequencies below 1 GHz in communications, the wavelength is already quite high resulting in problems when implementing the antennas into the UE, especially to portable UEs. A typical consumer handset length is around 100 mm and places for different antennas are li-mited by the volume of the industrial design. The industrial designs may be discovered with multiple form factors, multiple structures and dimensions. This causes problems in the antenna design as the available space/distances is/are limited. In addition, band-width is also highly dependent on the terminal size as small terminal size poses limits when designing antennas. Especially metal cover/metal parts in the design and thin mechanical design impacts antenna height, antenna distance to ground, antenna off- ground clearance and thus increases design challenges and may define achievable an-tenna performance parameters: bandwidth, frequencies, efficiencies, TRP performance, TIS performance, imbalance between antennas, isolations, distortion, radiation pattern,

for example.

To achieve as low a cost as possible all or special purpose radio frequency (RF) core functionalities may be integrated into a common RF integrated circuit (RFIC). Moreover, to minimize the PWB routing loss between a main antenna and a RFIC, the RFIC may be arranged to be as close as possible to the mainlfirst antenna.

However, it may be desirable to have multiple transmitters/receivers in the same fre- quency band and to increase the number of frequency bands to include lower frequen-cies as well. Multiple radio frequency (RF) blocks may be used to facilitate spatial separation and exploit the best locations in a terminal, a laptop, a handset, a UE, tablet device, a modem, etc. This may lead to a situation where PWB routing to other needed antennas (that may locate at the other end of the terminal) may be quite long with an equivalent PWB routing RF loss, which naturally is an unwanted feature to be avoided.

These needed routings to secondary antennas may limit possible form factors denoting the mechanical product concept implementations, such as a clam shell, a slide, a com- municator. That is, routings, for example trace length, connectors, cables length, isola-tion, interference, hinges, volume available for routing to second antenna locations may limit performance in different use-cases, like slide openlclosed, clam shell open/closed, monoblock, on cheek, on hand, and/or may limit mechanical concepts for tablets, laptops, monoblocks, etc. Accordingly, a RF integrated circuit (IC) may be designed to contain needed special purpose functionalities with a modem for the radio communication sys-tem where it is designed with conventional processing or vector processing. Needed diversity/MIMO functionalities may be implemented on the single special purpose RFIC or the system may contain multiple RFICs, which are physically equal or differ-ent RFICs, which may be controlled independently. From the RFIC point of view, the system may be built incorporating different combinations/features including the fol-lowing non-limiting examples: some RFICs may have Tx/Rx functionality, some may have Rx functionality only and some may have Tx functionality only. The needed Tx and Rx functionalities may be thus implemented on same RFIC, or on a different RFICs. A RFIC/combo module may have functionalities and interfaces for multiple communication systems concurrently. Other communication systems may be at least one of the following: Bluetooth, Zigbee, FM, radio data system (RDS), near field communication (NFC), global navigation satellite systems (GNSS), global positioning system (GPS), broadcasting TV transmitters/receivers, WLAN, or any other special purpose communication system. In an embodiment, at least some of the RFIC modem functionalities, processors, controllers, application processors, power management, etc. needed for the special purpose functionalities may be implemented as chips or a single chip. RFICs combinations to antenna systems may vary. In an embodiment, each RFIC may be connected to a respective antenna or an antenna may be shared with multiple RFICs and antenna connections may be altered according to the use-case, running ap-plications, active radios, sensor information, isolations, interferences, for example. In production of the terminal device or the modemlchipset, for example, there may be multiple combinations designed in order to support the different radio systems, differ- ent frequencies, different interoperability use-cases, etc. According to the system de-sign between the antenna and the RFIC, there may be special purpose RF parts in order to meet the radio specification standards, operator requirements and special require-ments for products.

It is to be understood that figure 1 is merely illustrative. The antenna count may vary with different combinations and the UE 110 may have more antennas than the eNB 100. For example, although Figure 1 shows two antennas 112 and 114 at the terminal device 100, the number of antennas in terminals may be more (which may likely increase the terminal costs). A cost effective solution may be achieved when each of the antennas do not need a separate housing (i.e. the number of housings is less than the number of antennas). The number of required dual active, dual HSPAILTE/LTE-A antennas is defined by a terminal class and the required minimum performance requirements. According to the terminal class/required performance, the number of antennas may increase in order to achieve required functionalities. Different example carrier aggregation (CA) cases may be, intra band CA, inter band CA, LTE and HSPA+, adjacent CA, non-adjacent CA, reception (Rx) CA, transmission (Tx) CA, etc. For example, upcoming carrier aggregation may benefit from the use of more antennas, for example. The carrier aggregation (CA) terminal may be active with dif-ferent frequency combinations such as, for example, LB+LB, HB+HB, LB+HB, HB+2.6GHz, wherein LB and HB denote low band and high band, respectively. 1.5 GHz radio systems may be count to the LB frequencies or the HB frequencies, as an example of frequency combinations. As indicated earlier, it is possible that the mul-tiple antenna structure becomes a single antenna structure having equal special purpose functionalities, characteristics and performance as the multiple antenna structure.

Moreover, neighboring antennas in an antenna arrangement may not be in-dependent of each other due to coupling that is present between the antennas. Thus, antenna isolation needs to be taken in account in the RF front end design and in the antenna system design for blocking, intermodulation, harmonic power, harmonic in-termodulation, adjacent channel leakage ratio (ACLR), wide band noise, component's power handling capability, electrostatic sensitive devices (ESD), interoperability be-tween radios/transceiver, etc. Common conductive connecting means may decrease the coupling, but it may not remove it completely. Further, a common ground (counter- poise) may couple the antenna elements. The coupling decreases as the separation be-tween antenna elements is made larger. Further factors that affect the coupling include antenna type selection, antenna material selection, antenna polarization selection, an-tenna radiator position, antenna radiation design, ground design, mechanical design, hand effects, material in proximity of antennas, antenna locations versus use case de- sign, for example. The coupling decreases the efficiency of the antenna as part of pow-er is lost to coupling. Coupling may also lead to saturation of the transceiver connected to a neighboring antenna. The small size of the terminal may cause increase in the coupling effect during use and also lead to decreased number of form factors. It may also decrease the use of mechanical change of structures and pose use limitations on the antennas.

Correlation between antennas is a measure (e.g. in the range from 0 to 1) of the receiving properties of two or more antennas. If correlation is high (i.e. approach- ing 1), then all antennas have similar properties and receive the same signal. In con- trast, when correlation is low (i.e. approaching 0), then each antenna has totally differ-ent receiving properties so they can receive different signals. Thus, low correlation (i.e. orthogonality) between the antennas is important for the MIMO/diversity operation in order to increase the MIMO/diversity receptionltransmission performance in the com-munication and thus increase the communication reliability. The orthogonality may be obtained by separating the antennas from each other by a half of a wavelength, or by a sub-wavelength, for example. To this end, there may be problems relating to the an-tenna arrangement in a terminal with MIMO/diversity receptionltransmission, which needs at least two concurrently active antennas. The correlation factors representing the correlation between the received signals easily tend to be between 0.5. . . .0.7, espe- cially at frequencies below 1 GHz. However, for MIMO reception the correlation fac- tor needs to be less than 0.5 to enable advantageous measureable reception perfor-mance gain for data throughput. Even smaller correlation is desired, for example less than 0.3. Achieving such a small correlation is cumbersome with low frequencies in small terminals, modems, handsets, tablets, laptops, finger computers, etc. Additional-ly, mechanical changes of a structure and user operation alters antenna characteristic and performance parameters and correlation.

For this reason it is proposed to take the antenna radiation patterns and/or radiation phase patterns into account for MIMO/diversity receptionltransmission in order to improve the data throughput while maintaining good reliability. A radiation pattern is basically a representation of electromagnetic power distribution in free space. The radiation pattern may have a certain phase, which may be represented with a radiation phase pattern. This allows antennas to be located and/or designed closer to each other, even in the same end of a terminal or in proximity of each other, thus keep-ing the number of antenna housings in a terminal device small and costs effective. The possibilities in industrial design are wide, thus the same end' of terminal is to be un-derstood without limitations (e.g. side or end). Moreover, the proximity of each other depends on the wavelength of frequency(s) in use. As an example, an implementation may comprise a rounded design or a sphere, where corners are difficult to define. In an altemative embodiment, the antenna(s) may be located on both sides of a corner or on multiple corners in horizontal/vertical/rotated directions. In an embodiment, it is pro-posed to apply a first antenna having a radiation phase pattern and at least one second antenna, each having a radiation phase pattern for transmitting and/or receiving radio frequency signals simultaneously via the air interface. Thus, multiple antennas or an-tennas in a single structure are to be applied in the transmission and/or in the reception simultaneously, thus enabling MIMO/diversity to be utilized. Each of the antennas also has a radiation pattern. The number of antennas to be applied is at least two with no upper limit. The antennas may be located as separate antennas and/or the antennas may be located in a single structure, for example. Each antenna may be connected to radio communication circuitry with a transmissionlreception signal path. The signal paths may eventually be combined in a radio modem for utilizing the MIMO/diversity that is obtainable from using different active antennas. In order to optimally utilize the MI-MO/diversity performance gain in the communication system, it is further proposed to introduce a phase shift between the radiation phase patterns of the associated antennas which are applicable in transmitting and/or receiving the radio frequency signals si-multaneously via the air interface, wherein the phase shift is introduced in order to obtain orthogonality between the associated radio frequency signals. The introduction of the phase shift may take place by virtue of the intrinsic design of the antennas or the required phase shift may be obtained by an in-use real-time electrical tuning of the antennas, the antenna circuitries, the RF front end circuitries with special purpose con-trol signals.

In an embodiment, the introduction of the phase shift between the radiation phase patterns of the associated antennas is obtained by performing at least one of the following: opening/closing at least one switch, and designing and/or electrically tuning at least one special purpose radio frequency component, wherein the at least one spe-cial purpose radio frequency component is located in at least one of the following: at least one of the associated antennas, at least one of the associated antenna circuitries and the radio front end. An associated antenna circuitry may be the antenna circuitry which corresponds to the associated antenna. The special purpose RF component may be fixed in design. Alternatively it may be a tunable component, such as electrically tunable. It may comprise an array of RF components. The special purpose RF compo-nent may be a capacitor, a coil, a duplexer, a filter, a diplexer, a triplexer, an isolator, a power amplifier, for example.

In an embodiment, when a mechanical change of structure (for example, change in the use-case) takes place, a low correlation may be achieved in the new posi-tion with product design or with altering/tuning/control signals. In an embodiment, the structure which position is changed may contain all antennas or antennas may be lo-cated in other structures, or combinations.

Although, as described above, a phase shift is introduced between the radi- ation phase patterns of the associated antennas in order to optimally utilize the MI-MO/diversity performance gain in the communication system, the radiation patterns of the associated antennas may have approximately equal shape, directions, etc. In an alternative or additional embodiment, the radiation patterns of the associated antennas may be rotated, may be made to be directed in different directions, may be made to have deformations in shape, etc. This may be applied to separate antennas and/or an-tennas in a single structure and combination of structures.

The orthogonality between the radio frequency signals denotes that the re- ceived/transmitted signals exhibit low mutual correlation so that a measurable MI-MO/diversity performance gain may be obtained. However, a total lack of correlation between the signals is neither required nor necessary, as described earlier. The level of correlation in order to reach the orthogonality may depend on the used frequency, for example. For low frequencies, such as below 1 GHz, the required level of correlation may be lower than for high frequencies due to implementation challenges. Further, at certain, relatively low frequency ranges, such as at <1 GHz or at -2GHz, low correla-tion is difficult to achieve in hand held devices, especially when the antennas are at same end of a terminal. By applying the appropriate phase shift between associated antennas, which causes the orthogonality between the associated signals, measureable diversity performance gain and/or measureable improved throughput of data, payload and/or information is obtained.

RF antennas may not radiate equally in all directions (i.e. they are not iso-tropic antennas). In fact, any realisable RF antenna design will radiate more energy in some directions than in others. The actual radiation pattem and the associated antenna bandwidth, for example, are dependent upon the type of antenna design, applied fre-quency, its size, the environment where the antenna is deployed, the ground distance, the ground clearance, off-ground area and shape, use case, mechanical change of struc- ture, other antennas in proximity, hand effect and a variety of other factors. This direc-tional pattern can be used to ensure that the power radiated is focussed in the desired directions. As frequency affects the pattern design, a so-called front-to-back ratio will fall off rapidly outside a given bandwidth and a carrier frequency, and so will the gain.

One way to affect the radiation pattern and/or the radiation phase pattern is to change the electrical length of the antenna which causes a change in the frequency related pa-rameters/characteristic/performance of the antennas, such as in a resonant frequency of the antenna. At the resonant frequency, which generally is the operation frequency of the antenna, only resistive impedance is present. Instead or in addition the radiation pattern may be modified by varying the phase of the radiation patterns of antennas.

Embodiments of the invention enable data streams/paths to be more uncor-related than if radiation patterns and/or radiation phase patterns were not taken into account. Further, the embodiments allow antennas in a single structure to be uncorre-lated even when they are physically close to each other. This is shown in Figure 8, where the envelope correlation coefficient (EEC) 800 between the received RF signals is depicted. It can be seen that already with an antenna separation of 0.1 of the wave-length, the achieved envelope correlation coefficient is 0.15, which is reasonably low for achieving a significant gain in reception. This allows the antenna terminals to be in the same end of a mobile phone, for example. This reduces the cost and/or RF routing loss. This is because the antennas may be designed with less antenna hous-ings/modules, which is cost efficient as housings/modules in both ends of a terminal may be avoided. The routing loss of the second antenna(s) may be lower than if the antennas were located in different ends and/or sides of the terminal. This is enabled by having the RF IC and RF front end components locate close to both the main and the diversity (second) antenna(s). Low routing loss is visible to a user by improved power levels in transmission and reception and battery life time.

Figure 2 shows exemplary radiation phase patterns 200 and 210 from two different antennas of the antenna arrangement in the terminal. According to an embo- diment, the radiation patterns are designed or tuned/altered such that the radiation pat-terns in a phase point of view (e.g. a radiation phase pattern) are substantially as shown in Figures 2A and 2B for two different antennas. In Figure 2A, a radiation phase pat-tern 200 of a first antenna is shown. The beams of the radiation phase pattern 200 shown with vertical lines may represent a first phase deviation of a radiation phase pattern, whereas beams of the radiation phase pattern 200 without vertical lines may represent a second phase deviation. In an example embodiment, the first phase devia-tion is about 60 degrees and the second phase deviation is around 240 degrees. It can be seen that the radiation phase pattern beams with 240 degrees phase deviation are located in the left lower part' and right higher part' of the radiation phase pattern 200 in Figure 2A for the first antenna. In Figure 2B, another second antenna may trans- mit/receive by using a radiation phase pattern 210. For the second antenna, the radia-tion phase pattern beams with 240 degree phase deviation are located in the left higher part' and right lower part' of the radiation phase pattern 210. Thus, there is about 180 (=240-60) degrees phase shift between the radiation phase patterns 200 and 210 of the two antennas. It is to be noted, even though Figure 2 depicts a two-dimensional X-Y representation of the antenna phase patterns, it is straight forward to imagine the radia-tion phase patterns in a three dimensional space co-ordinates.

As the two antennas simultaneously transmit/receive radio frequency sig-nals, the obtained two signals from the two antennas having phase shifted radiation patterns exhibit low mutual correlation. Thus, a measureable MIMO/diversity perfor-mance gain may be obtained. As can be seen from Figure 2, in an embodiment, a phase shift to be introduced between the radiation phase patterns, which phase shift causes orthogonality between the associated radio frequency signals, is substantially 180 de-grees. However, a different phase shift than 180 degrees may also be applied as long as the resulting radiation phase patterns differ such that the received/transmitted RF sig-nals are substantially orthogonal and measureable MIMO/diversity performance gain may be obtained. In other words, the phase shift between the antenna radiation phase patterns is applied so that the radiation patterns are not alike in phase point of view.

In order to introduce an appropriate phase shift between the radiation phase patterns, the associated antenna radiators may, in an embodiment, be designed to gen-erate a certain sufficient phase shift between the radiation phase patterns, which certain phase shift causes orthogonality between the associated radio frequency signals. Thus, the associated antennas may, prior to deployment, be designed to have the appropriate phase shift. Such design may comprise design of different components, dimensions, rotations, moves, use-cases, use-case instructions in manual. These may be aided with voice commands, with user interface commands, warning sounds, vibrations, volumes, mechanics and/or materials and selection of parameters/characteristic that are needed in the special purpose antenna arrangement, special purpose antenna circuitries, anten-na parasitic elements and/or mechanical concept when structure is changed and which affect the radiation pattern and/or the radiation phase pattern either directly or indirect-ly. In an embodiment multiple antennas may be designed and tested to be functional when embedded to mechanics, antenna housing elements, printed on PWB, flexible PWB, PWB modules, LTCC modules, for example. The parameters to design may include at least one of the following non-limiting list: electrical length of the antenna element, electrical distance between the antenna elements, electrical distance between the feed points of the antennas, electrical distance between ground connections, elec-trical distance between the feed point and the edge of the radio front end, such as the PWB edge, shielding, metal or corresponding material in proximity of the antenna, frequency, bandwidth, location of ground, phase of the feed signal (e.g. phase of the feed current), parameters related to impedance matching, etc. Changing any of the above mentioned parameters may affect the radiation pattern and/or the radiation phase pattern of the antenna. The correct parameter values may be obtained by testing and trying or they may be obtained with a mathematical model, for example. Implementa-tion details for different special purpose environments for different embodiments may be explained in product documentation, for example.

In one exemplary design structure the antenna feed points are located close to each other and off ground-antennas are used where ground material is removed in proximity of antennas. In this embodiment, as shown in Figure 9, the off-ground area 900 is separated from the PWB 902 area by removal of any metal material in the de- signed shape in the proximity of antenna. Alternatively antenna may be located in out-side of the PWB edge and thus not having metal in proximity of antenna. Antenna may be located with designed height above the level of the PWB. Alternatively, the PWB may have an opening below the antenna. Antenna feeds 904 and 906 may locate on the off-ground area and/or on a ground area, for example. The off-ground area may be lifted from the ground level by distance 908, for example. This embodiment allows for positioning the antenna feeds 904 and 906 at one end of the terminal close to each oth-er, such as 10 mm apart from each other or antennas in a single structure, yet keeping the correlation coefficient small in order to obtain orthogonality between the associated signals. The other end(s) and/or side(s) and/or corners of the terminal need not have antennas for functionality for enabling measurable diversity/MIMO performance gain.

In an ahernative embodiment, a terminal may support a higher data class (e.g. class 5 is specified for 4 antennas). The needed additional antennas may be lo-cated in the other end(s) and/or side(s) and/or corners of the terminal. The terminal or the network may request to alter the data class and, thus, the number of special purpose antennas, for example. The terminal/network may send information to net-work/terminal, respectively, capable to change the terminal class.

In an alternative embodiment, the UE/terminal may inform the network about current reception characteristic/performance parameters including the diversi- ty/MIMO correlation. Further, the network may request the terminal to al-ter/maintainlincrease/decrease the correlation in the communication.

In an embodiment, the UE/terminal may store the current reception charac- teristic/performance parameters including the diversity/MIMO correlation with alter- ing/tuning parameters to terminal memory or to external memory in the network, com- puter, processor, etc. for further analysis and improvement of diversity/MIMO recep-tion performance. This may happen during a component/module/antenna research, development and life cycle of a product.

The antenna or antennas in a single structure circuitry may be designed so that the required shift between different radiation phase patterns is obtained. The com-ponents within the circuitry may include power amplifiers, filters, duplexers, switches, isolators, power splitters, diplexers, phase shifters, couplers, matching components, antenna feed line, and other components, for example. Those may be active/passive, tunable, fixed or any combinations. The parameterization and modification of the above mentioned parameters and component in order to reach a desired phase shifted radiation pattem and/or radiation phase pattem with respect to another radiation pattern and/or radiation phase pattern may be obtained with testing, for example.

The design of the antenna or antennas in a single structure may also com-prise the selection of a proper antenna type. As known to a skilled person, different antennas have different properties. The selection of an individual antenna may be made from a vast variety of different antenna types comprising a dipole, a monopole, a pla-nar antenna, a horn antenna, a parabolic antenna, an F-type antenna, an isolated mode antenna technology (iMAT), antennas in a single structure, a whip antenna, to only mention a few of antennas well known to a skilled person. Some antennas are on-ground antennas, while others are so called off-ground antennas, where ground metal material is removed from antenna radiator proximity. Antennas may be implemented as wires, for example. However a variety of different antenna implementation tech-niques exist from different materials.

An antenna circuitry may be seen to feed the radio waves to the rest of the antenna structure in a transmit operation, or in a receive operation, antennas collect the incoming radio waves, convert them to electric currents and the antenna circuitry con-veys them to the receiver. Antennas typically consist of a feed line and an additional reflecting or directive structure whose function is to form the radio waves from the feed line into a beam or other desired radiation pattern. The antenna circuitry is usually considered to be all the components between the beam-shaping part of the antenna and the RF front end, including the feed points, the transmission line/path (i.e. a feed line/path or an antenna interface) and components on the transmission line that con-veys the signal between the antenna and the transceiver. Antenna typically needs at least one feed having a RF path connection. Additionally antenna may have none, one or more ground connections to which the feed line is at least operatively connected.

The transmission feed line may or may not locate on the printed wiring board of the terminal. Interconnection between antenna radiator and transceivers may be provided with galvanic connection(s) on the PWB, for example, or with coaxial cables, as ex-amples on how signals are conveyed between the radiation element and the RF front end. According to one example, in a laptop having a transceiver part below a keyboard base, the antenna radiators may be located in the base and/or in the proximity of the display structure. The radio frequency signals/control signals may be conveyed by coaxial cables, by flexible PWB, or by any combination of any conveying means, for example, between the functional parts of the special purpose system. The display may be a conventional display, a touch display, fixed or flexible or something else special purpose industrial design for communication.

Antenna impedance may be designed according to the special purpose de-sign. In an embodiment, the antenna impedances may be substantially equal. In another embodiment, introducing the phase shift between the associated radiation phase pat- terns takes place by designing or electrically tuning the antenna impedances of the as-sociated antennas to be unequal in order to obtain orthogonality between the associated radio frequency signals. As indicated, the selection of a high impedance, a low imped- ance, the equal or unequal impedance may be performed in the design and/or manufac-turing of the antenna and/or antenna circuitry or during operation by electrically tuning the impedance with control signals. The impedance of the antenna circuitry is selected according to implementation and antenna types. For example, approximately 50 ohms may be used. The antenna or antennas in a single structure and the antenna circuitry may have tuning possibility and controls may be provided for example with dedicated control interfaces, with radio frequencies over air interface or via galvanic connec-tion(s) to control unit, which generate the needed control signal(s). Controls may be provided with standardized control methods, ad-hoc control methods using various frequencies, modulations and amplitudes, etc. As indicated, the embodiments provide for fixed antenna structure where phase shift is introduced when designing the antenna characteristics. However, in an embodiment, the phase shift between the radiation phase patterns of the associated antennas is introduced by electrically tuning the current phase shift between the radia-tion phase patterns of the associated antennas in order to obtain orthogonality between the associated radio frequency signals. In this way the antenna characteristics of at least one of the associated antennas may be altered. The altering/tuning of the phase of the radiation pattern affects the radiation phase pattern, such as the phase pattern of Figures 2A and 2B, for example. These Figures are merely examples of radiation phase pattern shapes, wherein the shape may change according to the antenna design and during operation. The ahering/tuning may be obtained during use (i.e. practically in real time) by applying control signals from a controller. Embodiments relating to the tuning may contain control circuitry, control signals, feedback signals, information for controlling decisions, flow charts, look up tables to assist appropriate altering/tuning, for example. The electrical altering/tuning is performed by at least one of the follow- ing: at least one of the associated antennas, at least one of the associated antenna cir-cuitries, and the radio front end. For example, the tuning may be performed for the circuitry connected to a feed signal path, for the circuitry connected to a ground con-nection, for the parasitic load. Tuning control may take account of hysteresis, that is, it may apply the history knowledge of earlier tuning and the effects of earlier tuning.

The block diagram of Figure 3 shows a base band (BB) block 300 compris-ing a signal source 302 (in case of transmission) or a signal combiner 302 (in case of a receiver). The block 302 may be considered to represent the radio modem of the ter-minal. Block 300 may contain numerous other blocks as display, touch display, 2 display, flexible display, flexible user interface, earpiece, microphone, keypad, battery, connectors, proximity sensors, regulators, controllers, application processors, other special purpose radios according product. From the BB block 300, the signal is di-rected to the RF front end-block 306, which comprises components such as frequency converters, power amplifiers, fihers, duplexers, switches, isolators, power splitters, diplexers, phase shifters, couplers, detectors, antenna tuners, frequency band selectors, matching components and other components which may be needed in a special pur- pose RF system. These parts may be discrete, integrated circuits or modules with pas- sive, actively tunable, or fixed characteristics. Components may be fixed and/or tuna-ble with controls. Furthermore, components may be active and/or passive and those may be designed as modules. In the case of transmission, after the radio front end-block 306 are the interfaces 308 to 312, such as antenna feed lines. Naturally, there may be more or less than three interfaces, which is merely an example in Figure 3. The interface 308, for example, may be considered to be comprised in the antenna circuitry comprising all the components (including the associated components from a switch block 316) and conductive transmission line between the RF front end-block 306 and the antenna 318. Further, the antenna circuitries may or may not be connected to a ground 314. The switch block 316 may comprise switches that may be opened or closed with control signals 324 from the controller 304.

Antennas 318 to 322 may be located in same mechanical structure or at least some of them may be located in different mechanical structures. Furthermore, two or antennas may be designed to a module, which can be implemented in the de-sign. Antennas in the module may be tested so that they are designed to have tested/specified minimum correlation, e.g. EEC. One or more antennas in the module may be designed for interoperability. Isolation between antennas may have tested/specified minimum value. Antenna functionality in the module may be altered according active radios interoperability.

The controller 304 may be used to tune the antennas 318 and 322 with the control signals 324. The tuning of the antennas may comprise tuning of bandwidth, resonance, efficiency, gain, directivity, beam forming parameters, radiation, radiation phase parameters. A single antenna may have a single or multiple resonance frequen-cies, each of which may be tunable. The tuning may comprise changing the electrical length of the antenna or the special purpose antenna circuitry, for example. For this purpose, the antenna elements 318 to 322 or the antenna circuitries may be equipped with switches that may be opened/closed in order to change at least one of the electric- al length of the antenna structure, electrical length of the ground connection, termina-tion of ground connection, parasitics of the antenna, the phase of antenna feed and/or the ground feed, etc. In some embodiments, the antenna elements or the antenna circui- tries may be equipped with capacitors, coils, phase shifters, splitters, isolators and oth-er special purpose RF components which may be fixed or tunable with special purpose controls. The controls may come from a special purpose processor which generates controlling steps according to special purpose control sequence, for example. The change in the antenna circuitry may affect the resonance frequency(ies) of the antenna, for example. The change in the antenna circuitry affects the phase of the feed signal and, therefore, the phase of the radiation pattern (e.g., the radiation phase pattern) of the associated antenna. This allows for more efficient use of diversity. This is because the tuning of the antenna may be used to obtain the required phase shift between the antenna radiation phase patterns of the associated antennas.

In an embodiment, galvanic characteristics between at least two of the as-sociated antennas are altered/changed in order to control the phase shift, wherein the galvanic characteristics comprise at least one of the following: a distance, a phase of a signal and impedance of a related antenna circuitry. By tuning it is meant that the cha- racteristics may be altered/varied/changed. The signal may be any signal that is con-veys between the antennas, for example, the antenna feed signal. The related antenna circuitry may be the circuitry that is related to the any of the at least two antennas. The changing of the characteristics may be obtained by performing at least one of the fol-lowing: opening/closing at least one switch, and designing and/or tuning at least one special purpose radio frequency component, wherein the at least one special purpose radio frequency component is located in at least one of the following: at least one of the associated antennas, at least one of the associated antenna circuitries and the radio front end.

Looking at Figure 3, the switch block 316 comprises at least one switch that may be opened or closed by the control signal(s) 324 from the controller 304. The switches may be used to control the characteristics, such as the length, phase and im- pedance, of the feed transmission lines of the two associated antennas such that coupl- ing effect between the antennas is altered. In an embodiment, the altering of characte- ristics may be done by at least one of the following: a switch selection, a low imped-ance selection, a high impedance selection, a phase shift selection, for example. For example, the electronic distance between associated antennas may be altered. The switches and special purpose components in alternative interfaces may be used to alter the transmission feed line characteristics so that the electrical distance between the antenna 318 to 322 and the radio front end-block 306 is altered, thus affecting the phase of the feed signal and consequently the phase of the radiation pattern. The switches of the switch block 316 may further be used to alter the galvanic connection between the antennas when such galvanic connection exists via a conduct line. In an embodiment, galvanic characteristics between at least one of the associated antenna interfaces 308 to 312 and the ground 314 are changed in order to control the phase shift, wherein the galvanic characteristics comprise at least one of the following: a dis-tance, a phase of a signal and an impedance of a related antenna circuitry. The signal may be any signal that is conveyed between ground and the associated antenna, for example, the antenna ground feed signal. The related antenna circuitry may the circui-try that is related to the any of the at least one associated antenna. The changing of the characteristics may be obtained by performing at least one of the following: open-ing/closing at least one switch, and designing and/or tuning at least one special purpose radio frequency component, wherein thc at least one special purpose radio frequency component is located in at least one of the following: at least one of the associated an-tennas, at least one of the associated antenna circuitries and the radio front end.

Let us take a closer look of the controlling of the charactcristics, such as distances and electrical lengths in the antenna arrangement by using the switches. Fig-ure 4 shows a controller or a control circuitry 400 which may provide control signals 402 to 416 to components such as to switches 418 to 430 and to a RF front end 432 including the possibly tunable amplifiers, adaptive antenna matching unit, fihers, dup- lexers, diplexers, phase shifters, adaptive filter matching, tunable filters, tunable dup-lexers, tunable diplexers, band selectors, for example. The transmission feed lines 448 and 450, also called the interfaces, to antennas 440 and 442, respectively, may or may not be connected to a ground 434. To this end it should be noted that any change in the antennas or in the electrical antenna circuitry (feed point, feed path, ground connec-tion, etc.), affects the phase relation between the antenna radiation patterns. It should also be noted that each of the switch blocks 418 to 430 may comprise a single switch or a plurality of switches.

The control signal 402 is aimed to the RF front end for tuning the compo- nents within the RF front end. These components may need tuning according to trans-missionlrcception frequencies, transmission/reception activity, modulation, bandwidth, different transmit power, reception power, diversity/MIMO operation, carrier aggrega- tion operation, when the use-case situation alters, interoperability, when the mechani-cal structure changes, for example. Control circuit 400 may be located in the RF front end, in the RFIC, in a power management unit, in any special purpose controller, in the BB block, in the special purpose application processors. Figure 4 shows only a simpli-fled figure for clarity.

The special purpose control signals 404 and 406 may be used to electrical-ly open/close the switches 418 and 420, respectively. Let us assume that the switch block 418 comprises two parallel switches, a first and a second switch. When the con-trol signal 404 opens the first switch and closes the second switch, the electric current to the antenna 442 runs via the closed second switch. The electrical length, phase, and/or impedance of the route via the second switch may be different than via the first switch. Thus, the electrical impedance, phase and/or length of the feed line (a.k.a. the interface) may be altered. As the coupling connects the two antennas together and the coupling takes place between the circuitries of the antennas, the electrical characteris-tics, such as the distance, phase and/or impedance between the two antennas and the coupling may be controlled by the use of the switches in the feed line.

Even though it is shown that some of the switches are located in the anten-na feed paths 448 and 450, they or some of them may instead be located elsewhere in the antenna circuitry or be connected to the antenna circuitry in order to tune the an-tennas and/or the antenna circuitries. In an embodiment, at least some of the switches may be located in the PWB of the terminal device, antenna housings, mechanical hous-

ings, as examples.

As indicated, the transmission feed line 450 may this way be electrically adjustable which affects the phase of the feed signal to the antenna 430 and therefore alters the phase of the radiation pattem 446.

In an embodiment, the feed signal phase may be designed/altered/tuned in a modem in order achieve the desired phase in the feed signals which affects the phase of the feed signal to the antenna and therefore alters the phase of the radiation pattern.

The same may be done in the network side. Different delays and /or phases of different frequency signals may be measured in the design phase and stored to memory or processing code to be used in order to achieve MIMO diversity performance gain in the design or during use by tuning/altering. The terminal and the network may com-municate between each other the special purpose parameters/characteristics prior and/or after the change of parameters/characteristics. The same may be done in con- junction with beamforming. Therefore, by applying appropriate phases of the feed sig-nals, a beam directed to desired direction may be formed. The appropriate phases may be obtained by testing or by applying mathematical modeling, for example.

The control signals 408 and 410 are for electrically tuning the galvanic characteristics, such as the distance, the phase and/or the impedance, between the inter-face and the ground, when such ground connection exists, by opening/closing switches 422 and 424, respectively. The connection line between the feed line 448 and the ground 434 may be equipped with a parallel pair of switches 422, for example. When a first switch is open and a second switch is closed, the distance between the ground 434 and the feed 448 is different from the distance when the first switch is closed and the second switch is open. In this way the distance to the ground 434 may be varied. Al- ternatively or in addition, a switch may be applied in selecting between a high imped-ance state, and a low impedance state, or to introduce different phase shifts between the radiation phase patterns. Varying the characteristics, such as distance, impedance and/or phase, affects the phase of the radiation pattern due to changed phase of the signal. In another embodiment, as shown in Figure 10, the ground feed 1006 from the ground 1000 to the antenna feed path 1002 forms a U-shape. The distance may then be altered with a switch 1004 which have the effect that closing the switch 1004 shortens the ground feed line 1006 as electricity may flow without the U-shape. The open-ing/closing of the switch 1004 may be controlled with electrical control signals from the controller (CTRL). In alternative embodiment, the U-shape may have multiple switches for the distance adjustment.

The control signal 412 is for electrically tuning the galvanic connection be-tween the antennas by opening closing the switch 426. Again the switch 426 may comprise a plurality of switch elements. When the connection between the antenna elements is closed (i.e. connection exists via a conduct line, not merely coupling), the coupling may be decreased as the electric current may flow via the conduct line where the switch 426 is located. By having parallel switches in the switch block 426, the elec-trical distance and the electrical connection, special purpose impedances between the antennas may be tuned, which affects the phase of the feed signal and the phase of the radiation pattern.

It should be noted that the switch and the switch blocks in the Figures may also represent special purpose RF components or special purpose RF functionalities which may be designed or tuned to alter the impedances, phase, lengths, and distances between two elements, for example. This affects the phase of the feed signal and the phase of the radiation pattern (the phase radiation pattern). The special RF components may comprise tunable coils, tunable capacitors, tunable filters, tunable duplexers, tun-able diplexers, etc. The control signals 414 and 416 may be used to electrically tune the anten-nas 440 and 442 with respective switches 428 and 430. As indicated the electrical length of the antenna may be made longer or shorter by using the switches. Similarly, the impedance may be changed. This affects the antenna characteristics, including the frequency related parameters and, in particular, the phase of the radiation pattern. As a result, the radiation patterns 444 and 446 of the antennas 440 and 442 may be tuned/altered by appropriately changing the phase shift between the radiation phase patterns. The patterns 444 and 446 may be made to have, for example, 180 degrees phase shift between a first and a second antenna which allows measureable improve- ment in diversity/MIMO performance in the associated transmitted/received RF sig-nals. Also, this may be of use when interference is present at some frequency and this frequency is to be avoided (i.e. shift away from interference frequency range). Alterna- tively or in addition to, isolation between interfering and victim antennas may be in-creased by altering radiation pattern and/or the radiation phase pattern.

In an embodiment, the controller 400 obtains feedback 438 related to per- formed radio communication. Based on the feedback 438, the controller 400 may per- form the electrical altering/tuning of the phase shift between the radiation phase pat-terns of the associated antennas. Thus, when the controller 400 obtains information that diversity/MIMO performance gain is not as desired, the controller 400 may decide to tune/alter the phase shift of the radiation phase patterns of the associated antennas.

When this type of closed loop tuning is performed, the feedback may be obtained from at least one of the following: the RF block 432, the BB 300 of Figure 3, a radio mod-em, special purpose controller, a power management IC, a dedicated feedback circuitry 436, an application processor, for example. The feedback information may be origi- nated from detectors, proximity sensors, circuitries having connection to the RF trans- missionlreception paths, information may be extracted from communication parame-ters, processed from receptionltransmission signal parameters. The feedback related to the radio communication may comprise information about the applied use-case, the mechanical structural of the device, interoperability, etc. Interoperability feed-back/information may contain for example information about an interference source system, interference source systems, and/or interference victim systems. Further feed- back information may be, for example, radio frequencies, transmission power(s), re- ception power(s), ACLR power(s), wideband noise level(s), in-band spurious lev-el(s)/frequency(s), out-of-band spurious levels/frequencies, harmonics frequencies and power levels, intermodulation results and power levels, blocking frequencies and pow-er levels. The network parameters and downlink/uplink quality parameters may be utilized and quality parameters may be calculated in the radio modem for controlling purposes. The calculated output may contain information about which antenna radiator parameters need to be tuned/altered and/or which antennas need to be replaced by a third antenna radiator in order to achieve a measureable diversity/MIMO performance improvement. The feedback may be for example data throughput, reception quality indicator, ACK and NAK relation, network feedback signal, correlation calculated from by the radio modem, etc. The feedback may be analog or digitally controlled by a standard control system or the control system may be chipset specific. However, in-stead of closed loop tuning, an open loop tuning may be performed without feedback signals.

In an embodiment, the tuning is performed on the basis of at least one of the following: transmission/reception frequency, transmission/reception activity, transmission/reception bandwidth, number of carriers, modulation, diversity/MIMO operation, and carrier aggregation operation. That is, when change in the radio com-munication related parameters is needed, the tuning of the antenna 440 and 442 or the radio front end -block 434 may be triggered, for example. The tuning of the radio communication related parameters may then be followed by or combined with tun-ing/altering the radiation pattems and/or the radiation phase patterns in any of the means as provided by the embodiments or combinations of the embodiments.

In an embodiment, at least one of the associated antennas is replaced with another antenna on the basis of at least one of the following: transmission/reception activity, mechanical change in the structure of a terminal device comprising the anten- nas, interference level, transmission/reception power level(s), transmission band-widths, modulation, interoperability between different radio functionalities and change in carrier aggregation configuration. The replacement may also be based on a change in the diversity/MIMO radio parameters. The replacing may be part of tuning process.

The replacement may be obtained with switches by opening a switch to the currently associated antenna and conveying the feed signal to another antenna by closing the switch or switches that correspond to that antenna. The transmission/reception activity may comprise switching between Tx and Rx antennas when transmission and reception are to take place in adjacent turns. Further criteria for replacing an antenna may in-clude whether or not multiple radios are active concurrently, interoperability between the radios, etc. When interference is present at one antenna, the antenna may be re- placed with another. When received power is high, an antenna connected to compo- nents of low power tolerance may be replaced with another antenna connected to com-ponents of higher tolerance or with antennas having higher isolation. Alternatively, the radiation pattern of an antenna with low power tolerance may be tuned so that less power is received. When bandwidth is changed, the antenna may need to be changed as well to better cope with the required bandwidthlfrcquency/carrier aggregation re-quirements. The change of the antenna also affects the electrical distance between the feed points of the associated antennas.

The mechanical change in the structure of a terminal device may comprise, for example, slide open/closed, hinge open/closed, clam shell open/closed. Thus, the apparatus comprising the antenna arrangement may comprise detectors and/or sensors for detecting such changes in the mechanical structure of the terminal device. When such change is detected, the controller 400 may replace an antenna with another anten-na which is located in a more optimal position with respect to the MIMO/diversity reception performance gain. Further criteria for replacing an antenna with another may comprise the position of the terminal device. The sensors and detectors may also be responsible of determining the position and placement of the terminal device. Such positions may comprise cheek, hand, table, above knees, for example. When an anten-na is located against a table, for example, it may be advisable to replace that antenna with another. Therefore, special purposes steps and/or functionalities may be executed by a controller in order to achieve a measureable diversity/MIMO performance im-provement.

Figure 5 shows a flow diagram for introducing the phase shift between the radiation patterns and electrically altering/tuning the radiation patterns and/or the radi-ation phase pattern when needed. In step 500, at least two antennas are simultaneously applied, thus corresponding to a multiple antenna transmissionlreception. In step 502, a phase shift is introduced by designing the antennas in an appropriate manner as de-scribed above or by tuning the antennas during use. Consequently, data communication may be performed by applying the introduced phase shift in step 504. Next, in step 506, it is determined whether or not a change in the phase shift is needed. The need to change may be obtained on the basis of the feedback or as part of reconfiguring the system. If the answer is negative, then communication may be continued at step 508.

However, if the answer is positive, then step 510 may be followed wherein another phase shift is introduced by tuning the characteristics of the antenna, the antenna cir-cuitry, the radio front ends, or by replacing the antennas in use with another antenna, for example. In any case, a new phase shift that corresponds to orthogonal signal transmission/reception in the prevailing situation is obtained. The tuning at this step may be any of the tuning methods described above such as altering the galvanic dis- tance between antennas, altering the galvanic connection between the antennas, alter- ing the impedance and/or phase of the antenna feed path and altering the galvanic dis-tance between the antenna feed points and the ground plane, for example. After the newly introduced phase shift is obtained, the communication may be started/continued with the new phase shift in step 504.

Figure 6 illustrates a method for increasing diversity in multi-antenna communication. The method starts in step 600. In step 602, the method comprises in-troducing a phase shift between radiation phase patterns of associated antennas which are applicable in transmitting and/or receiving radio frequency signals simultaneously via an air interface, wherein the phase shift is introduced in order to obtain orthogo-nality between the associated radio frequency signals. The method ends in step 604.

In an embodiment, as shown in Figure 7, an apparatus 700 comprises at least one processor 702 and at least one memory 704 including a computer program code, wherein the at least one memory 704 and the computer program code are config-ured, with the at least one processor 702, to cause the apparatus 700 to carry out any one of the above-described processes relating to the tuning/altering of the antenna, the antenna circuitry, the radio front end circuitry, for example. It should be noted that Figure 7 shows only the elements and functional entities required for understanding the apparatus 700. Other components have been omitted for reasons of simplicity. The implementation of the elements and functional entities may vary from that shown in Figure 7. The connections shown in Figure 7 are logical connections, and the actual physical connections may be different. The connections can be direct or indirect and there can merely be a functional relationship between components. It is apparent to a person skilled in the art that the apparatus may also comprise other special purpose functions and special purpose structures. The apparatus 700 may be implemented as a unit or module and have analog, digital, power, antenna interfaces, for example.

The apparatus 700 may comprise the terminal device of a cellular commu-nication system, e.g. a computer (PC), a laptop, a tablet computer, a cellular phone, a communicator, a smart phone, a communication unit, a smart book, a palm computer, or any other communication apparatus. In another embodiment, the apparatus is com-prised in such a terminal device, e.g. the apparatus may comprise a circuitry, e.g. a chip, a processor, a micro controller, or a combination of such circuitries in the termi- nal device and cause the terminal device to carry out the above-described functional-ities. Apparatus may be part of chipset. Further, the apparatus 700 may be or comprise a module (to be attached to the UE) providing connectivity, such as a plug-in unit, an "USB dongle", or any other kind of unit. The unit may be installed either inside the UE or attached to the UE with a connector or even wirelessly.

As indicated, the apparatus 700 may comprise the at least one processor 702. The at least one processor 702 may be implemented with a separate digital signal processor provided with suitable software embedded on a computer readable medium, or with a separate logic circuit, such as an application specific integrated circuit (AS-IC). The at least one processor 702 may comprise an special purpose interface(s), such as a computer port, for providing communication capabilities.

The at least one processor 702 may comprise a special purpose control cir-cuitry 712 The control circuitry 712 may be responsible from performing the tuning based on the control signal provided by the control circuit 712. The at least one proces- sor 702 may also comprise a feedback circuitry 710 for providing feedback to the con-troller circuitry 712, as described above. The feedback circuitry 710 may determine the correlation (EEC) values from received information and this way inform the control circuitry of possibly needed tuning/altering.

The apparatus 700 may further comprise radio interface components 706 (TRX) providing the apparatus with radio communication capabilities with the radio access network. The radio interface components 706 may comprise standard well-known components such as amplifier, filter, frequency-switches, other special purpose RF components, converter, (de)modulator, and encoder/decoder circuitries and one or more antennas. The TRX 706 may comprise a plurality of switches, a capacitor bank, a coil bank, capacitors, coils, etc. that are used in tuning the phase shifts of the antenna radiation patterns and/or the radiation phase patterns according to any of the embodi-ments.

As indicated, the apparatus 700 may comprise a memory 704 connected to the processor 702. However, memory may also be integrated to the processor 702 and, thus, no memory 704 may be required. The memory may be for storing data related to tuning functions, such as look-up tables, feedback information, etc. In an embodiment, parameters that may be tuned and the appropriate values of the parameters may be ob-tained in production and stored to memory for further use. That is, in use, the memory may be used to retrieve correct values for certain parameters that need to be tuned. For example, with certain frequency certain electrical characteristics of the antenna circui-try may be needed. The certain electrical characteristics may be stored in memory and by knowing the characteristics, correct switches or correct amount of switches may be opened or closed or capacitors/coils/phase shifters may be tuned, thus obtaining suita-ble length, distance, phase or impedance, for example.

In an embodiment, at least one configuration comprising tuning instrnction for at least one of the following: at least one of the associated antennas, at least one of the associated antenna circuitries and the radio front end is stored in the memory, wherein each configuration produces a certain phase shift. Consequently, the network element performing the tuning, may then apply an appropriate configuration from the memory when the certain phase shift is to be obtained between the radiation phase patterns of the associated antennas. This has the advantage that computational re-sources may not need to be applied in that point for calculating the configuration.

There may be a plurality of configurations. The parameter values for the RF compo-nents, the switches to be opened/closed, etc. may be obtained through testing in the design phase, or via mathematical modeling, for example.

In an embodiment, different design structures are stored and the apparatus may be caused to select one of the stored design structures. The different design struc-tures may be obtained when the associated antenna radiators, the radio front end and/or the associated antenna circuitries are designed to generate a certain phase shift between the radiation phase patterns. Thereafter, the selected design structure may be used in the antenna arrangement.

As used in this application, the term circuitry' refers to all of the follow- ing: (a) hardware-only circuit implementations, such as implementations in only ana-log and/or digital circuitry, and (b) combinations of circuits and software (and/or firmware), such as (as applicable): (i) a combination of processor(s) or (ii) portions of processor(s)/software including digital signal processor(s), software, and memory(ies) that work together to cause an apparatus to perform various functions, and (c) circuits, such as a microprocessor(s) or a portion of a microprocessor(s), that require software or firmware for operation, even if the software or firmware is not physically present.

This definition of circuitry' applies to all uses of this term in this application. As a further example, as used in this application, the term circuitry' would also cover an implementation of merely a processor (or multiple processors) or a portion of a proces-sor and its (or their) accompanying software and/or firmware. The term circuitry' would also cover, for example and if applicable to the particular element, a baseband integrated circuit or applications processor integrated circuit for a mobile phone or a similar integrated circuit in a server, a cellular network device, or another network de-vice.

As indicated, the apparatus 700 may also be or be comprised in a module which can be attached to the apparatus whose antenna patterns may need to be con-trolled. The module may naturally contain also other components than antenna and those may comprise proximity sensors, antenna matching components, adaptive anten- na matching, etc. The module may be simply attached to the PWB of the terminal de-

vice, for example.

The invention provides several advantages. For example, data through-put/speed may be increased with measureable amount. Moreover, the antenna locations impact the terminal's form factor, allow dimensions to be decreased and thus different kind of terminal structures and use cases. The embodiments improve the network ca-pacity because it reduces the fail rate in data package reception and may thus allow use of higher data classes.

The techniques and methods described herein may be implemented by various means. For example, these techniques may be implemented in hardware (one or more devices), firmware (one or more devices), software (one or more modules), or combinations thereof For a hardware implementation, the apparatus(es) of embodi-ments may be implemented within one or more application-specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGA5), proces-sors, controllers, micro-controllers, microprocessors, other electronic units designed to perform the functions described herein, or a combination thereof For firmware or software, the implementation can be carried out through modules of at least one chip set (e.g. procedures, functions, and so on) that perform the functions described herein.

The software codes may be stored in a memory unit and executed by special purpose processors. The special purpose memory unit may be implemented within the proces-sor or externally to the processor. In the latter case, it can be communicatively coupled to the processor via various means, as is known in the art. Additionally, the compo- nents of the systems described herein may be rearranged and/or complemented by ad-ditional components in order to facilitate the achievements of the various aspects, etc., described with regard thereto, and they are not limited to the precise configurations set forth in the given figures, as will be appreciated by one skilled in the art.

Thus, according to an embodiment, the apparatus comprises processing means configure to carry out embodiments of any of the Figures 1 to 10. In an em-bodiment, the at least one processor 702, the memory 704, and the computer program code form an embodiment of processing means for carrying out the embodiments of the invention.

In an embodiment, the apparatus comprises processing means configured to perform the tasks of Figures 1 to 10.

Embodiments as described may also be carried out in the form of a com-puter process defined by a computer program. The computer program may be in source code form, object code form, or in some intermediate form, and it may be stored in some sort of carrier, which may be any entity or device capable of carrying the pro- gram. For example, the computer program may be stored on a computer program dis-tribution medium readable by a computer, a processor, or a special purpose device able to execute commands. The computer program medium may be, for example but not limited to, a record medium, computer memory, read-only memory, electrical carrier signal, telecommunications signal, and software distribution package, for example.

Even though the invention has been described above with reference to an example according to the accompanying drawings, it is clear that the invention is not restricted thereto but can be modified in several ways within the scope of the appended claims. Therefore, all words and expressions should be interpreted broadly and they are intended to illustrate, not to restrict, the embodiment. It will be obvious to a person skilled in the art that, as technology advances, the inventive concept can be imple- mented in various ways. Further, it is clear to a person skilled in the art that the de- scribed embodiments may, but are not required to, be combined with other embodi-ments in various ways.

Claims

Claims 1. A radio communications method, comprising: introducing a phase shift between radiation phase pattems of associated an-tennas for transmitting and/or receiving radio frequency signals simultaneously via an air interface, wherein the phase shift is introduced in order to obtain or increase ortho-gonality between the associated radio frequency signals.
2. The method of claim 1, wherein the phase shift is introduced by design-ing associated antenna radiators, a radio front end and/or associated antenna circuitries to generate a certain phase shift between the radiation phase pattems.
3. The method of any of claims 1 to 2, wherein the phase shift is intro- duced by electrically tuning the current phase shift between the radiation phase pat-tens of the associated antennas in order to obtain or increase orthogonality between the associated radio frequency signals.
4. The method of claim 3, wherein the electrical tuning is performed to at least one of: at least one of the associatcd antennas, at least one of associated antenna circuitries and a radio front end.
5. The method of any of claims 3 to 4, further comprising: changing galvanic characteristics between at least two of the associated an-tennas, wherein the galvanic characteristics comprise at least one of: a distance, a phase of a signal and an impedance of a related antenna circuitry.
6. The method of any of claims 3 to 5, wherein galvanic characteristics are changed between at least one of the associated antenna interfaces and a ground in order to control the phase shift, wherein the galvan- ic characteristics comprise at least one of: a distance, a phase of a signal and an imped-ance of a related antenna circuitry.
7. The method of any of claims 3 to 6, further comprising: obtaining feedback related to performed radio communications; and electrically tuning the phase shift between the radiation phase patterns of the associated antennas on the basis of the feedback.
8. The method of any of claims 1 to 7 wherein the phase shift is introduced by designing and/or electrically tuning antenna impedances of the associated antennas to be unequal in order to obtain or increase orthogonality between the associated radio frequency signals.
9. The method of any of claims 1 to 8, wherein the introduction of the phase shift between the radiation phase patterns of the associated antennas is obtained by performing at least one of opening/closing at least one switch, and designing and/or electrically tuning at least one special purpose radio frequency component, wherein the at least one special purpose radio frequency component is located in at least one of at least one of the associated antennas, at least one of the associated an-tenna circuitries and the radio front end.
10. The method of any of claims 1 to 9, wherein the phase shift, which causes or increases orthogonality between the associated radio frequency signals, is substantially 180 degrees.
11. The method of any of claims 1 to 10, further comprising: replacing at least one of the associated antennas with another antenna on the basis of at least one of transmissionlreception activity, mechanical change in the structure of a terminal device comprising the antennas, interference level, transmis- sionlreception power level, transmission bandwidths, modulation, interoperability be-tween different radio functionalities, and change in carrier aggregation configuration.
12. The method of any of claims 1 to 11, further comprising: storing to a memory at least one configuration comprising a tuning instruc-tion for at least one of: at least one of the associated antennas, and at least one of the associated antenna circuitries and the radio front end, wherein each configuration pro-duces a certain phase shift; and applying an appropriate configuration from the memory when the certain phase shift is to be obtained between the radiation phase patterns of the associated an-tennas.
13. A radio communications apparatus, comprising: a processor arranged to: introduce a phase shift between radiation phase pattems of associated an- tennas which are for transmitting and/or receiving radio frequency signals simulta-neously via an air interface, wherein the phase shift is introduced in order to obtain or increase orthogonality between the associated radio frequency signals.
14. The apparatus of claim 13, wherein the phase shift is introduced by de- signing associated antenna radiators, a radio front end and/or associated antenna circui-tries to generate a certain phase shift between the radiation phase patterns.
15. The apparatus of any of claims 13 to 14, wherein the phase shift is in- troduced by electrically tuning the current phase shift between the radiation phase pat-terns of the associated antennas in order to obtain or increase orthogonality between the associated radio frequency signals.
16. The apparatus of claim 15, wherein the electrical tuning is performed to at least one of: at least one of the associated antennas, at least one of associated anten-na circuitries and a radio front end.
17. The apparatus of any of claims 15 to 16, which is further arranged to: change galvanic characteristics between at least two of the associated an-tennas, wherein the galvanic characteristics comprise at least one of: a distance, a phase of a signal and an impedance of a related antenna circuitry.
18. The apparatus of any of claims 15 to 17, wherein the galvanic characte-ristics are changed between at least one of the associated antenna interfaces and a ground in order to control the phase shift, wherein the galvanic characteristics com- prise at least one of: a distance, a phase of a signal and an impedance of a related an-tenna circuitry.
19. The apparatus of any of claims 15 to 18, wherein the apparatus is fur-ther arranged to: obtain feedback related to performed radio communication; and electrically tune the phase shift between the radiation phase patterns of the associated antennas on the basis of the feedback.
20. The apparatus of any of claims 13 to 19, wherein the apparatus is fur-ther arranged to: introduce the phase shift by designing and/or electrically tuning antenna impedances of the associated antennas to be unequal in order to obtain orthogonality between the associated radio frequency signals.
21. The apparatus of any of claims 13 to 20, wherein the introduction of the phase shift between the radiation phase patterns of the associated antennas is ob-tamed by performing at least one of: opening/closing at least one switch, and designing and/or electrically tuning at least one special purpose radio frequency component, wherein the at least one special purpose radio frequency component is located in at least one of: at least one of the associated antennas, at least one of the associated an-tenna circuitries and the radio front end.
22. The apparatus of any of claims 13 to 21, wherein the phase shift, which causes orthogonality between the associated radio frequency signals, is substantially degrees.
23. The apparatus of any of claims 13 to 22, wherein the apparatus is fur-ther arranged to: replace at least one of the associated antennas with another antenna on the basis of at least one of: transmission/reception activity, mechanical change in the struc- ture of a terminal device comprising the antennas, interference level, transmis- sionlreception power level, transmission bandwidths, modulation, intcroperability be-tween different radio functionalities, and change in carrier aggregation configuration.
24. The apparatus of any of claims 13 to 23, wherein the apparatus is fur-ther arranged to: store to a memory at least one configuration comprising a tuning instruc- tion for at least one of at least one of the associated antennas, at least one of the asso-ciated antenna circuitries and the radio front end, wherein each configuration produces a certain phase shift; and apply an appropriate configuration from the memory when the certain phase shift is to be obtained between the radiation phase patterns of the associated an-tennas.
25. An apparatus comprising means configured to cause the apparatus to carry out the method according to any one of claims 1 to 12.
26. A computer program product embodied on a distribution medium read-able by a computer and comprising program instructions which, when loaded into an apparatus, execute the method according to any of claims 1 to 12.
27. A radio communications apparatus comprising plural antennas which are adapted and/or are adaptable to transmit and/or receive, simultaneously, orthogonal radio frequency signals.
28. A radio communications apparatus substantially as herein described and/or as illustrated by the accompanying drawings.
29. A radio communications method substantially as herein described and/or as illustrated by the accompanying drawings.Amendments to the claims have been made as follows: Claims 1. A radio communications method, comprising: introducing a phase shift between radiation phase patterns representing the phases of radiation patterns of associated antennas for receiving radio frequency sig-nals simultaneously via an air interface, wherein the phase shift is introduced so that the radiation phase patterns are substantially un-correlated with respect to one another whereby the associated radio frequency signals are substantially un-correlated with respect to one another.2. The method of claim 1, wherein the phase shift is introduced by design-ing associated antenna radiators, a radio front end and/or associated antenna circuitries C\i to generate a certain phase shift between the radiation phase patterns. r3. The method of any of claims 1 to 2, wherein the phase shift is intro- duced by electrically tuning the current phase shift between the radiation phase pat-o terns of the associated antennas.4. The method of claim 3, wherein the electrical tuning is performed to at least one of: at least one of the associated antennas, at least one of associated antenna circuitries and a radio front end.5. The method of any of claims 3 to 4, further comprising: changing galvanic characteristics between at least two of the associated an-tennas, wherein the galvanic characteristics comprise at least one of: a distance, a phase of a signal and an impedance of a related antenna circuitry.6. The method of any of claims 3 to 5, wherein galvanic characteristics are changed between at least one of the associated antenna interfaces and a ground in order to control the phase shift, wherein the galvan- ic characteristics comprise at least one of: a distance, a phase of a signal and an imped-ance of a related antenna circuitry.7. The method of any of claims 3 to 6, further comprising: obtaining feedback related to performed radio communications; and electrically tuning the phase shift between the radiation phase patterns of the associated antennas on the basis of the feedback.8. The method of any of claims 1 to 7 wherein the phase shift is introduced by designing and/or electrically tuning antenna impedances of the associated antennas to be unequal.C\i 9. The method of any of claims 1 to 8, wherein the introduction of the phase shift between the radiation phase patterns of the associated antennas is obtained by performing at least one of: opening/closing at least one switch, and designing and/or electrically tuning at least one special purpose radio frequency component, o wherein the at least one special purpose radio frequency component is located in at least one of: at least one of the associated antennas, at least one of the associated an-tenna circuitries and the radio front end.10. The method of any of claims 1 to 9, wherein the phase shift between the radiation phase patterns is substantially 180 degrees.11. The method of any of claims 1 to 10, further comprising: replacing at least one of the associated antennas with another antenna on the basis of at least one of: transmission/reception activity, mechanical change in the structure of a terminal device comprising the antennas, interference level, transmis- siorilreception power level, transmission bandwidths, modulation, interoperability be-tween different radio functionalities, and change in carrier aggregation configuration.12. The method of any of claims ito 11, further comprising: storing to a memory at least one configuration comprising a tuning instruc-tion for at least one of: at least one of the associated antennas, and at least one of the associated antenna circuitries and the radio front end, wherein each configuration pro-duces a certain phase shift; and applying an appropriate configuration from the memory when the certain phase shift is to be obtained between the radiation phase patterns of the associated an-tennas.13. A radio communications apparatus, comprising: means arranged to: introduce a phase shift between radiation phase patterns representing the phases of radiation patterns of associated antennas which are for receiving radio fre- C'\J queney signals simultaneously via an air interface, wherein the phase shift is intro-r..duced so that the radiation patterns are substantially un-correlated with respect to one another whereby the associated radio frequency signals are substantially un-correlated with respect to one another. C)14. The apparatus of claim 13, wherein the phase shift is introduced by de- signing associated antenna radiators, a radio front end and/or associated antenna cir-cuitries to generate a certain phase shift between the radiation phase patterns.15. The apparatus of any of claims 13 to 14, wherein the phase shift is in- troduced by electrically tuning the current phase shift between the radiation phase pat-terns of the associated antennas.16. The apparatus of claim 15, wherein the electrical tuning is performed to at least one of: at least one of the associated antennas, at least one of associated anten-na circuitries and a radio front end.17. The apparatus of any of claims 15 to 16, which is further arranged to: change galvanic characteristics between at least two of the associated an-tennas, wherein the galvanic characteristics comprise at least one of: a distance, a phase of a signal and an impedance of a related antenna circuitry.18. The apparatus of any of claims 15 to 17, wherein the galvanic charac-teristics are changed between at least one of the associated antenna interfaces and a ground in order to control the phase shift, wherein the galvanic characteristics com- prise at least one of: a distance, a phase of a signal and an impedance of a related an-tenna circuitry.19. The apparatus of any of claims 15 to 18, wherein the means is further arranged to: C\i obtain feedback related to performed radio communication; and electrically tune the phase shift between the radiation phase pattems of the associated antennas on the basis of the feedback.o 20. The apparatus of any of claims 13 to 19, wherein the apparatus is fur-ther arranged to: introduce the phase shift by designing and/or electrically tuning antenna impedances of the associated antennas to be unequal.21. The apparatus of any of claims 13 to 20, wherein the introduction of the phase shift between the radiation phase patterns of the associated antennas is ob-tained by performing at least one of: opening/closing at least one switch, and designing and/or electrically tuning at least one special purpose radio frequency component, wherein the at least one special purpose radio frequency component is located in at least one of: at least one of the associated antennas, at least one of the associated an-tenna circuitries and the radio front end.22. The apparatus of any of claims 13 to 21, wherein the phase shift is sub-stantially 180 degrees.23. The apparatus of any of claims 13 to 22, wherein the means is further arranged to: replace at least one of the associated antennas with another antenna on the basis of at least one of: transmissionlreception activity, mechanical change in the struc- ture of a terminal device comprising the antennas, interference level, transmis- sionlreception power level, transmission bandwidths, modulation, interoperability be-tween different radio ftinctionalities, and change in carrier aggregation configuration.24. The apparatus of any of claims 13 to 23, wherein the means is further arranged to: store to a memory at least one configuration comprising a tuning instruc- C\i tion for at least one of: at least one of the associated antennas, at least one of the asso-r. ... . ciated antenna circuitries and the radio front end, wherein each configuration produces a certain phase shift; and apply an appropriate configuration from the memory when the certain o phase shift is to be obtained between the radiation phase patterns of the associated an-tennas.25. An apparatus according to any of claims 13 to 24 wherein the means comprises a processor.26. A radio communications apparatus according to any of claims 13 to 25 further comprising plural antennas for transmitting and/or receiving, simultaneously, the associated substantially un-correlated radio frequency sigiials.27. A computer program product embodied on a distribution medium read-able by a computer and comprising program instructions which, when loaded into an apparatus, execute the method according to any of claims 1 to 12.28. A radio communications apparatus according to claim 13 and as sub-stantially as herein described and/or as illustrated by the accompanying drawings.29. A radio communications method according to claim 1 and as it has been substantially as herein described and/or as illustrated by the accompanying draw-ings. c\J r C)