Apparatus and Method for Channel Filtering

Abstract

A user equipment, method and computer program for adjusting an effective center frequency of a channel filter in a user equipment to improve adjacent channel selectivity when a network transmits on an irregular bandwidth channel and the user equipment receives signals via a channel filter with a passband wider than the channel bandwidth. The method includes filtering a received wireless communication signal at the channel filter. A preferred center frequency of the channel filter is identified by: adjusting the center frequency of the channel filter; determining a level of adjacent channel selectivity of the signal filtered by the channel filter; comparing the levels of adjacent channel selectivity at different center frequencies of the channel filter; and identifying the preferred center frequency as the center frequency that provides the highest level of adjacent channel selectivity.

Description

Technical Field

[0001] Various example embodiments relate to channel filtering in a user equipment, and particularly to providing support for irregular bandwidths at the user equipment through appropriate configuration of a receiver and a channel filter. Background Art

[0002] A user equipment may have a channel filter configured to receive signals within a predefined bandwidth. The filter is typically configured such that the bandwidth is consistent with the bandwidth of a New Radio (NR) channel.

[0003] To efficiently use licensed spectrum, wireless channels with "irregular" bandwidths may be used. These are channels with bandwidths that are inconsistent with the bandwidths of existing NR (New Radio) channels. Although this can enable more efficient use of the spectrum, the filters of the user equipment may not be suitable for these irregular bandwidths. One solution may be for the user equipment to use the next wider bandpass filter, i.e., a filter with a passband wider than the channel bandwidth, such that the entire channel is received. One drawback of doing so is that when the filter extends beyond the channel, signals from adjacent channels that appear as noise will be received.

[0004] There is a desire to efficiently use the spectrum of a licensed frequency band without unduly increasing the noise received from adjacent channels at the user equipment. Summary of the Invention

[0005] The scope of protection sought by various embodiments of the present invention is defined by the independent claims. Embodiments / examples and features (if any) described in this specification that do not fall within the scope of the independent claims will be construed as examples useful for understanding the various embodiments of the present invention.

[0006] According to various but not necessarily all embodiments of the present invention, there is provided, according to a first aspect, an apparatus comprising: at least one component for filtering a wireless communication signal received on a channel, the component for filtering passing signals within a predefined bandwidth and attenuating signals outside the predefined bandwidth; a component for identifying a preferred center frequency of the at least one component for filtering, the component for identifying comprising: a component for adjusting an effective center frequency of the at least one component for filtering; a component for determining a level of adjacent channel selectivity of a signal filtered by the at least one component for filtering; a component for comparing levels of adjacent channel selectivity of the at least one component for filtering at different center frequencies and identifying the preferred center frequency as the center frequency providing the highest adjacent channel selectivity.

[0007] The apparatus has a filtering component configured to pass a desired received wireless communication signal within the bandwidth of the channel for which it is configured and filter out undesired signals outside that bandwidth. The filtering component can function as a band-pass or low-pass filter within the channel bandwidth. In some cases, it can function as a band-pass or low-pass filter outside the channel bandwidth. It should be noted that the receiver can have a down-conversion component for converting the frequency of the received channel to a lower frequency, and the filtering component can receive the signal from the down-conversion component. In the case where the down-conversion component is a zero-IF or homodyne conversion component, the filtering component can be a low-pass filter. In the case where the down-conversion component is a superheterodyne conversion component, the down-conversion component can convert the frequency of the received channel to an intermediate frequency, and the filtering component can be a band-pass filter.

[0008] The width of the bandwidth passed by the filtering component for the channel can be predefined, but the effective center frequency of the filtering component for the channel can be adjustable. The effective center frequency of the component for filtering the channel depends on the center frequency of the filter relative to the center frequency of the channel it is filtering. Thus, the adjustment component can change the effective center frequency of the filtering component by reconfiguring the filtering component or by adjusting the center frequency of the received signal channel sent to the filtering component.

[0009] The position of the effective center frequency of the filtering component can affect adjacent channel selectivity (ACS). ACS is a measure of the ability of a radio receiver to receive a signal on a desired channel or frequency in the presence of another signal on an adjacent frequency or channel. Thus, ACS is affected by the signal on the adjacent channel, and the preferred or optimal center frequency of the filtering component will vary with operating conditions, particularly with the signal level on the adjacent channel. Therefore, being able to determine the ACS at different center frequencies allows determination of the preferred center frequency of the filtering component. This can be done by comparing different levels of ACS at different configured effective center frequencies and selecting the effective center frequency that results in the highest adjacent channel selectivity. This can correspond to the center frequency that provides the maximum attenuation of adjacent channel interference or the center frequency that provides the minimum adjacent channel interference falling within the filter passband.

[0010] In some example embodiments, the above apparatus responds to the above identification component identifying an updated preferred center frequency to adjust the center frequency of the above filtering component to the updated preferred center frequency.

[0011] In some example embodiments, the above component for determining the level of the above adjacent channel selectivity includes a component for determining the signal-to-interference-plus-noise ratio, an increase in which indicates an increase in the attenuation of adjacent channel interference.

[0012] In some example embodiments, the above-described apparatus includes components for control; the components for control respond to the reception of a network signal indicating that the network supports at least one irregular bandwidth channel that does not correspond to the bandwidth of one of the at least one component for filtering to: select one of the at least one component for filtering that has a bandwidth wider than the at least one irregular bandwidth; and trigger the component for identification to identify the preferred center frequency of the selected component for filtering.

[0013] In some example embodiments, the network signal may simply be a signal indicating support for some use of a channel with an irregular bandwidth. In other example embodiments, the network signal may be a signal indicating a change to a downlink channel including an irregular bandwidth. The signal may be a reconfiguration signal. The reconfiguration signal may be a channel reconfiguration signal such as an RRC (Radio Resource Configuration signal) message.

[0014] In some example embodiments, the above-described component for adjustment is configured to adjust the effective center frequency by: increasing the effective center frequency by an amount equal to half of the difference between the bandwidth of the selected component for filtering and the irregular bandwidth; and decreasing the effective center frequency by the above amount.

[0015] In some example embodiments, the above-described component for control is configured to trigger the component for identifying the preferred center frequency of the at least one component for filtering in response to at least one of the following:

[0016] A predefined time interval;

[0017] The power of the received signal is higher than a predetermined level;

[0018] The signal-to-interference-plus-noise ratio; and

[0019] An indication that the above-described apparatus is moving at a speed above a predetermined speed.

[0020] In some example embodiments, the component includes: at least one processor; and at least one memory including computer program code, the at least one memory and the computer program code being configured to, together with the at least one processor, cause the apparatus to perform.

[0021] According to various but not necessarily all embodiments of the present invention, there is provided an apparatus including: at least one channel filter for filtering a received wireless communication signal; circuitry configured to identify a preferred center frequency of the at least one channel filter, the circuitry configured to identify including: circuitry configured to adjust an effective center frequency of the at least one channel filter; circuitry configured to determine a level of adjacent channel selectivity of a signal filtered by the at least one channel filter; and circuitry configured to compare levels of adjacent channel selectivity of the at least one channel filter at different center frequencies and identify the preferred center frequency as the center frequency providing the highest level of adjacent channel selectivity.

[0022] In some example embodiments, the apparatus responds to the circuitry configured to identify identifying an updated preferred center frequency to adjust the effective center frequency of the channel filter to the updated preferred center frequency.

[0023] In some example embodiments, the circuitry configured to determine the level of adjacent channel selectivity includes circuitry configured to determine a signal-to-interference-plus-noise ratio, an increase in which indicates an increase in attenuation of adjacent channel interference.

[0024] In some example embodiments, the apparatus includes: circuitry configured to control, the circuitry configured to control in response to receiving a network signal indicating that the network supports at least one irregular bandwidth channel not corresponding to the bandwidth of one of the at least one channel filters to: select one of the at least one channel filters having a bandwidth wider than the at least one irregular bandwidth; and trigger the circuitry configured to identify to identify the preferred center frequency of the selected channel filter.

[0025] In some example embodiments, the circuitry configured to adjust is configured to adjust the effective center frequency by: increasing the effective center frequency by an amount equal to half the difference between the bandwidth of the selected channel filter and the irregular bandwidth; and decreasing the effective center frequency by the amount.

[0026] In some example embodiments, the circuitry configured to control is configured to trigger the circuitry configured to identify the preferred center frequency for the at least one channel filter in response to at least one of: a predefined time interval; the power of the received signal being above a predetermined level; the signal-to-interference-plus-noise ratio; and an indication that the apparatus is moving above a predetermined speed.

[0027] According to various but not necessarily all embodiments of the present invention, there is provided a method according to a second aspect, the method comprising: filtering a received wireless communication signal using at least one channel filter; identifying a preferred center frequency of the at least one channel filter by: adjusting an effective center frequency of the at least one channel filter; determining a level of adjacent channel selectivity of a signal filtered by the at least one channel filter; comparing the levels of adjacent channel selectivity of the at least one channel filter at different center frequencies; and identifying the preferred center frequency as the center frequency that provides the highest level of adjacent channel selectivity.

[0028] In some example embodiments, the method further comprises the step of adjusting the effective center frequency of the at least one channel filter to the preferred center frequency.

[0029] In some example embodiments, the step of determining the level of adjacent channel selectivity comprises determining a signal-to-interference-plus-noise ratio, an increase in which indicates an increase in adjacent channel selectivity.

[0030] In some example embodiments, the method comprises:

[0031] In response to receiving a network signal indicating that the network supports an irregular bandwidth channel that does not correspond to the bandwidth of the at least one channel filter:

[0032] selecting one channel filter among the at least one channel filter that has a bandwidth wider than the irregular bandwidth channel; and

[0033] initiating the identifying step to identify a preferred center frequency of the selected channel filter.

[0034] In some example embodiments, the step of adjusting the effective center frequency comprises: increasing the effective center frequency by an amount equal to half of a difference between the bandwidth of the selected channel filter and the irregular bandwidth channel; and decreasing the effective center frequency by the amount.

[0035] In some example embodiments, the method comprises: performing the step of identifying the preferred center frequency of the at least one channel filter in response to at least one of the following:

[0036] a predefined time interval;

[0037] the power of the received signal being higher than a predetermined level;

[0038] the signal-to-interference-plus-noise ratio; and

[0039] an indication that the device is moving above a predetermined speed.

[0040] According to various but not necessarily all embodiments of the present invention, there is provided a computer program which, when executed by a processor on a device, is configured to control the above-mentioned device to perform the method according to the second aspect.

[0041] Other specific and preferred aspects are set out in the appended independent and dependent claims. The features of the dependent claims may be appropriately combined with the features of the independent claims and may be combined with features other than those explicitly set out in the claims.

[0042] Where a device feature is described as being operable to provide a function, it should be understood that this includes a device feature that provides the function or is adapted or configured to provide the function. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Some example embodiments will now be described with reference to the accompanying drawings, in which:

[0044] Figure 1 shows how an irregular bandwidth channel is generated at the network and received at the user equipment;

[0045] Figure 2 shows the adjacent channel selectivity problems that may occur when the next wider bandwidth channel filter is selected;

[0046] Figures 3A to 3C schematically shows how adjacent channel selectivity varies with the center frequency of the channel filter;

[0047] Figure 4 schematically shows receiver measurements for determining adjacent channel selectivity using a wider bandwidth channel filter;

[0048] Figure 5 schematically shows the effect of shifting the center frequency of a mobile receiver or channel filter for channel filter optimization;

[0049] Figure 6 schematically shows the continuous optimization of a channel filter based on SINR measurements;

[0050] Figure 7 schematically shows the adjustment of the center frequency of a filter as a function of the center frequency of a configured carrier;

[0051] Figure 8 schematically shows a flowchart showing the steps of a method according to an example embodiment; and

[0052] Figure 9 schematically shows a user equipment according to an example embodiment. DETAILED DESCRIPTION

[0053] Before discussing the example embodiments in more detail, an overview will first be provided.

[0054] Embodiments provide a way to support irregular bandwidth configurations at a user equipment. In some cases, the network is seeking to use new channel bandwidths with higher granularity (compared to the conventional minimum 5 MHz bandwidth in NR). The user equipment typically has one or more channel filters, each configured with a bandwidth corresponding to one of the channels that the network typically supports. In the case of using an irregular bandwidth that does not correspond to the channel filter bandwidth, then receiving signals with potentially overlapping spectra can be a problem.

[0055] Example embodiments solve this problem by selecting a bandpass filter that is wider than the bandwidth of the irregular channel and adjusting the effective center frequency to a position that provides increased adjacent channel selectivity. This is an enhanced attenuation of signals outside the irregular bandwidth channel.

[0056] Figure 1 An example of how the network can support new bandwidths by combining overlapping carriers at the gNB side is shown. There are different ways to achieve this capability, such as a wider channel BW (bandwidth), overlapping CA (carrier aggregation), or overlapping channel BW from the network side. One possible implementation can involve overlapping the RF (radio frequency) channel BW at both the network side and the UE side, which provides improved channel filtering and spectral utilization. However, this technique is not supported at the UE side. Figure 1 Schematically shows how an irregular BW channel is generated at the network to be received at the UE.

[0057] This enhanced concept and implementation of irregular bandwidths meet the needs of network providers to purchase spectra that do not necessarily match the existing 3GPP BW definitions. The problem is that the UE faces challenges in correctly receiving overlapping spectra. UE vendors are suggesting that the UE can configure the channel BW to the next wider channel bandwidth, which means that if the BW is configured by the NW (network) to be, for example, 7 MHz, the UE should apply the configuration of the next wider bandwidth of 10 MHz. This approach will clearly raise concerns about adjacent channel selectivity ACS (especially when adjacent spectral blocks belong to different operators such that coexistence cannot be guaranteed), because adjacent channels become insufficiently filtered. Figure 2 Schematically shows the UE applying a filter that is wider than the BW of the signal transmitted from the NW, and shows how the filter fails to correctly attenuate the received signals from potentially strong adjacent channels, because a portion of these signals will be received within the passband of the channel filter.

[0058] Although this problem can be solved by adding NW support, this will involve additional signaling between the NW and the UE and related overhead. In addition, if this becomes a network management issue, cross-operator cross-consistency of UE conditions is required, especially when the UE is located at the cell edge.

[0059] Such a proposal not only introduces new signaling but also poses a complex (almost impossible in some cases) task of collecting information for the required signaling on the NW.

[0060] It would be desirable if this problem could be solved without or with minimal signaling from the network.

[0061] The example embodiments utilize the ability of the UE receiver to measure the ACS to self-adjust the most optimal position of the channelization filter for a given irregular bandwidth configuration. Thus, the example embodiments focus on an alternative to the ACS processing problem that still allows the UE to utilize the next wider channel bandwidth, but does not require signaling and supports signal generation via overlapping RF carriers on the network side as one of the deployment options.

[0062] In the example embodiments, reception of signals in channels with irregular bandwidths can even be supported by appropriately configured legacy UEs that are configured to measure the ACS and place the effective center frequency of the next wider channel filter at a position determined based on the best SINR measurement.

[0063] The potential improvement of the ACS by moving the effective center frequency of the channel filter is schematically shown in Figures 3A to 3C These figures illustrate how the movement of the center frequency of the channel filter changes the amount of signal from adjacent channels passed by the filter. In the example shown, one of the adjacent channels in the adjacent channels has a much stronger signal than the other adjacent channel, such that placing the channel filter to overlap with the weaker signal rather than the stronger signal can reduce the amount of signal energy received from the adjacent channel. The change in the effective center frequency of the channel filter is shown in these figures by a change in the filter bandwidth. Another way to adjust the effective center frequency of the channel filter is to move the frequency of the received signal in the opposite direction by a corresponding amount. In the case where the receiver has a downconversion component, then performing effective center frequency adjustment at the downconversion component may be cost-effective.

[0064] It can be seen that the UE will be able to evaluate the SINR of each of the three presented cases by making, for example, 3 measurements, and then place the next wider channel BW channelization filter at the center frequency of the channel providing the best SINR. This method does not require gNB monitoring and signaling to support the UE with the channel filter configuration because the UE can make the measurements itself. InFigures 3A to 3C In the example of Figure 3C the filter setting, which results in the best SINR and the lowest interference level from adjacent channels.

[0065] Examples of how to measure and configure ACS measurements are described in detail below.

[0066] The UE can perform ACS estimation at any time, which means that even if the network is not configured with an irregular bandwidth, it can do so to prepare for future configurations and can immediately select the preferred position of the channel filter. In the case where the operating band has more frequency allocations than currently used, then the UE can configure a wider receiver bandwidth (wider passband channel filter) for the receiver to check the SINR, as Figure 4 schematically shown.

[0067] To avoid or at least suppress a severe degradation in the ongoing reception, this can be planned by the UE in a short period of time and when it is in good signal conditions (e.g., RSRP (Reference Signal Received Power) is higher than a threshold). As mentioned before, the UE has the ability to perform the desired measurements to identify the SINR under wider BW operation. The time for these measurements can be set in various ways.

[0068] It can be performed continuously before the channel BW reconfiguration so that when the reconfiguration occurs, the UE knows the preferred center frequency and can immediately provide an improved next wider BW channel filter configuration. Alternatively, it can be triggered when receiving an RRCReconfiguration message that configures the BW to an irregular BW (i.e., the next wider BW is required).

[0069] For the continuous or ongoing case, the UE will be at risk of signal quality during the measurement instance because it broadens the RX BW, but at the same time when the network configures an irregular bandwidth, it enables the UE to hit the next wider BW at the optimal or at least improved position of the center frequency of the receiver. It may be necessary for the UE to know the configured BW to calculate the exact center frequency required for the filter with the next wider BW, but the UE can apply the maximum irregular BW and estimate where the best SINR can be obtained.

[0070] For the RRCReconfiguration-triggered update, the UE makes measurements at different center frequencies, some of which provide a poor SINR before it can place the RX filter at the preferred or optimal frequency position. The optimal placement is achieved when the SINR is the best.

[0071] Figure 5Schematically shows the signal strength from adjacent channels, and how to move the center frequency from the center to a lower frequency position and then to a higher frequency position to bring the noise signal into the passband of the filter. The higher frequency position has lower noise from adjacent channels and is preferred.

[0072] As a further fine-tuning, the UE can optionally continue to iterate the new position of the effective center frequency of the channel filter to further balance the interference levels on either side of the channel, thereby further improving the SINR in the slot-to-slot process (see Figure 6 ).

[0073] If the balance of power or the presence of adjacent channels changes, the UE can continuously move the center frequency of the receiver to obtain an optimal or at least improved SINR. f c,filter (The selection of the center frequency of the channel filter) remains an internal configuration, which means that the NW will never be informed of the actual center frequency that the UE is using during the channel filtering phase.

[0074] Those skilled in the art will recognize that the effective center frequency of the channel filter can be adjusted by changing the center frequency of the channel filter itself or by changing the center frequency of the channel that is the input signal to the channel filter. For example, it can be changed by reconfiguring the channel filter and / or by shifting the frequency of the input channel signal by a desired amount. In this regard, the receiver in the UE can have a homodyne or heterodyne down-conversion circuitry associated therewith. This down-conversion circuitry shifts the center frequency of the received channel to a lower frequency. In the presence of such circuitry, a simple way to adjust the effective center frequency of the filter can be to simply use the circuitry to adjust the amount by which the channel is offset.

[0075] The process of measuring and adjusting the center frequency of the filter (independent of runtime) can be explained as follows:

[0076] 1. The UE calculates the center frequency of the filter, f c,filter , which center frequency f c,filter is set to the next wider BW as a function of the center frequency f c,carrier of the configured carrier, where the configured irregular BW is called BW configured , and the next wider BW is called BW next wider , as shown in Figure 7 .

[0077] a. In Figure 7 , 3 measurements are made, but the UE can decide to make more than 3 measurements in order to achieve a finer placement of f c,filter .

[0078] 2. Measure the SINR for each filter setting, i.e., SINR A , SINR B , SINR C

[0079] 3. Select the f corresponding to the maximum SINR c,filter .

[0080] 4. Periodically repeat the measurement for refinement if necessary

[0081] a. The UE can repeat at time intervals defined within the UE

[0082] b. The UE can repeat based on criteria such as SINR or RSRP thresholds or mobility status.

[0083] Figure 8 A flowchart is provided which schematically shows the steps for measurement and adjustment regarding the above-mentioned center frequency. Initially at step D5, the UE is monitoring the signal and when it receives a signal indicating that an irregular bandwidth channel is supported by the network, it proceeds to step S10. This signal can be a general signal indicating that a part of the network the UE is entering supports irregular bandwidth channels, or it can be a reconfiguration signal such as an RRC message indicating that the network will use a specific irregular bandwidth channel. At step S10, the UE selects a channel filter with a bandwidth wider than the irregular bandwidth channel it is interested in. At this point, if it has received an RRC configuration signal, it knows the irregular bandwidth to be used and will select a channel wider than this irregular bandwidth. If it has only received a signal indicating support for irregular channels, it will perform measurements on the irregular channel bandwidths that it knows or predicts the network may use, such that when the network does switch to such a channel, it has already determined the position for the channel filter which is optimal or at least preferable for that particular configuration.

[0084] At step S20, the center frequency of the filter is set to the center of the irregular bandwidth channel under consideration. At step S30, the attenuation level of adjacent channel interference is measured. This can be a measurement of the signal-to-interference-plus-noise ratio SINR.

[0085] Then in step S40, in this case, the center frequency of the channel filter is adjusted by increasing the frequency, and step S30 is repeated and the attenuation level of the adjacent channel interference is performed again. In step S50, another adjustment of the center frequency of the channel filter is performed, and in this case, it is adjusted by reducing the frequency to a level lower than the original center frequency, and step S30 is performed again, and the attenuation level of the adjacent channel interference at this position with this center frequency is performed. These steps of adjusting the center frequency and measuring the attenuation level can be performed multiple times, and once the required number of times is performed, then in step S60, the attenuation levels for different positions of the center frequency are compared and the center frequency that gives the highest attenuation level is selected.

[0086] In step S70, the center frequency of the channel filter is set to this value, and in this way, improved attenuation of the signals from the adjacent channels is achieved and improved adjacent channel selectivity is provided. It should be noted that in the case where these measurements are made as background measurements before the network uses an irregular channel, at this time step S70 is not performed, and simply the result of the comparison is stored in case the network does switch to using that particular irregular bandwidth channel, whereby the comparison result is retrieved and step S70 is performed.

[0087] Figure 9 User equipment UE 5 according to an example embodiment is schematically shown. UE 5 has a receiving circuitry 8 for receiving signals in this example embodiment, the receiving circuitry including a down-conversion component for down-converting the frequency of the received signals and two channel filters 10A, 10B having different bandwidths. In this example embodiment, channel filter 10A serves as a band-pass filter with a passband of 5 MHz, while channel filter 10B serves as a band-pass filter with a passband of 10 MHz. UE5 also has a control circuitry 12 and an identification circuitry 20, the control circuitry 12 being configured to control which channel filter is used for receiving signals, and the identification circuitry 20 being for identifying the preferred center frequency of the operating channel filter. The identification circuitry 20 includes an adjustment circuitry 22 for adjusting the effective center frequency of channel filter 10A or 10B, a determination circuitry 24 for determining the adjacent channel selectivity level of the signals filtered by the operating channel filter 10A or 10B, and a comparator 26 for comparing the different adjacent channel selectivity levels determined by the determination circuitry 24, so that the preferred center frequency, which is the center frequency that provides the highest level of adjacent channel selectivity, can be identified.

[0088] Once the identification component 20 has identified the preferred center frequency of a particular channel filter, the conditioning circuitry 22 can adjust the effective center frequency of the operating channel filter to the preferred value when the channel filter is operational and an irregular bandwidth channel is received. In some embodiments, the effective center frequency can be adjusted by adjusting the frequency of the signal input to the channel filter at the downconversion component.

[0089] The control circuitry 12 can be used to trigger the identification circuitry 20 to identify the preferred center frequency of a particular channel filter at a particular time when it deems that an update of that value and / or a previously determined value may be helpful. It can perform this operation periodically at predefined time intervals, and / or it can perform this operation in response to determining that the signal conditions at the UE are good such that measurements can be tolerated without unduly affecting UE performance. For example, this may be the case where the power of the received signal is above a predetermined level or the signal-to-interference-plus-noise ratio is above a predetermined level. The control circuitry can also trigger these measurements to be performed when it determines that the UE is moving above a predetermined speed. In the case where the UE is moving rapidly, then the adjacent channel conditions may change and thus the preferred center frequency may also change.

[0090] In summary, the example embodiments provide a method for improving UE performance in terms of robustness to adjacent channel interference at the UE without NW signaling.

[0091] Those skilled in the art will readily recognize that the steps of the various above-described methods can be performed by a programmed computer. In this document, some embodiments also aim to cover program storage devices, such as digital data storage media, which are machine or computer-readable and encode machine-executable or computer-executable programs of instructions, where the above instructions perform some or all of the steps of the above methods. The program storage device can be, for example, a digital memory, a magnetic storage medium such as disks and tapes, a hard disk drive, or an optically readable digital data storage medium. Embodiments also aim to cover a computer programmed to perform the above steps of the above methods.

[0092] As used in this application, the term "circuitry" can refer to one or more or all of the following:

[0093] (a) A pure hardware circuit implementation (such as an implementation using only analog and / or digital circuitry), and

[0094] (b) A combination of hardware circuitry and software, such as (where applicable):

[0095] (i) A combination of (multiple) analog and / or digital hardware circuitry and software / firmware, and

[0096] (ii) Any portion of (a) hardware processors (including (a) digital signal processor(s)), software, and (a) memory(memories) with software that work together to cause a device, such as a mobile phone or a server, to perform various functions, and

[0097] (c) (A) hardware circuit(s) and / or (a) processor(s), such as (a) microprocessor or a portion of (a) microprocessor(s), that require software (e.g., firmware) to operate, but the software may be absent when not needed for operation.

[0098] The definition of circuitry applies to all uses of the term in this application, including in any claim. As another example, as used in this application, the term circuitry also encompasses implementations of only a hardware circuit or a processor (or processors) or a portion of a hardware circuit or a processor and its (or their) accompanying software and / or firmware. For example, if applicable to a particular claim element, the term circuitry also encompasses a baseband integrated circuit or a processor integrated circuit for a mobile device, or a similar integrated circuit in a server, a cellular network device, or other computing or network device.

[0099] Although embodiments of the present invention have been described in the preceding paragraphs with reference to various examples, it should be understood that the examples given can be modified without departing from the scope of the claimed invention.

[0100] The features described in the preceding description can be used in other combinations than those explicitly described.

[0101] Although functions have been described with reference to certain features, these functions can be performed by other features, whether or not described.

[0102] Although features have been described with reference to certain embodiments, these features may also be present in other embodiments, whether or not described.

[0103] Although the foregoing specification has sought to draw attention to those features of the invention that are regarded as particularly important, it should be understood that the applicant claims protection for any patentable feature or combination of features mentioned above and / or shown in the drawings, whether or not specifically emphasized.

Claims

1. An apparatus (5) for channel filtering, comprising: At least one component (10A, 10B) configured to filter a wireless communication signal received over a channel, the component configured for filtering passing signals within a predefined bandwidth and attenuating signals outside the predefined bandwidth; A component (20) configured to identify a preferred center frequency of the at least one component configured for filtering, the component configured for identification comprising: A component (22) configured to adjust an effective center frequency of the at least one component configured to filter the channel; A component (24) configured to determine a level of adjacent channel selectivity of a signal filtered by the at least one component configured for filtering; A component (26) configured to compare levels of adjacent channel selectivity of the at least one component configured for filtering at different center frequencies and identify the preferred center frequency as the center frequency providing the highest level of adjacent channel selectivity; and A component (12) configured for control, the component configured for control responsive to receipt of a network signal indicating that the network supports at least one irregular bandwidth channel not corresponding to the bandwidth of the at least one component configured for filtering to: Select one of the at least one component configured for filtering having a bandwidth wider than the at least one irregular bandwidth; and to Trigger the component configured for identification to identify a preferred center frequency of the selected component configured for filtering, Wherein the component configured for adjustment is configured to adjust the effective center frequency to different center frequencies by: Increasing the effective center frequency by an amount equal to half of a difference between the bandwidth of the selected component configured for filtering and the irregular bandwidth; and Decreasing the effective center frequency by the amount.

2. The apparatus according to claim 1, the apparatus identifying an updated preferred center frequency in response to the component configured for identification to adjust the effective center frequency of the component configured for filtering to the updated preferred center frequency.

3. The apparatus according to claim 1, wherein The component configured to determine the level of adjacent channel selectivity comprises a component configured to determine a signal-to-interference-plus-noise ratio, an increase in the signal-to-interference-plus-noise ratio indicating an increase in attenuation of adjacent channel interference.

4. The apparatus according to claim 1, wherein the network signal comprises a signal indicating a change to a downlink channel including an irregular bandwidth.

5. The apparatus according to claim 1, wherein the component configured for control is configured to trigger the component configured to identify the preferred center frequency of the at least one component configured for filtering in response to at least one of: A predefined time interval; The power of a received signal being above a predetermined level; The signal-to-interference-plus-noise ratio; and An indication that the apparatus is moving above a predetermined speed.

6. The apparatus according to any one of the preceding claims, wherein the components configured for identification and the components configured for control comprise: at least one processor; and at least one memory including computer program code, the at least one memory and the computer program code being configured to, with the at least one processor, cause the apparatus to perform.

7. A method for channel filtering, comprising: filtering a received wireless communication signal using at least one channel filter; identifying a preferred center frequency for the at least one channel filter by: adjusting an effective center frequency of the at least one channel filter; determining a level of adjacent channel selectivity of a signal filtered by the at least one channel filter; comparing the levels of adjacent channel selectivity of the at least one channel filter at different center frequencies; and identifying the preferred center frequency as the center frequency providing the highest level of adjacent channel selectivity; and in response to receiving a network signal indicating that an irregular bandwidth channel not corresponding to the bandwidth of the at least one channel filter is supported by the network: selecting one channel filter among the at least one channel filter having a bandwidth wider than the irregular bandwidth channel; and initiating the identifying step to identify the preferred center frequency of the selected channel filter, wherein the step of adjusting the effective center frequency to different center frequencies comprises: increasing the effective center frequency by an amount equal to half of a difference between the bandwidth of the selected channel filter and the irregular bandwidth channel; and decreasing the effective center frequency by the amount.

8. The method according to claim 7, the method further comprising the step of adjusting the effective center frequency of the at least one channel filter to the preferred center frequency.

9. The method according to claim 7, wherein the step of determining the level of adjacent channel selectivity comprises determining a signal-to-interference-plus-noise ratio, an increase in the signal-to-interference-plus-noise ratio indicating an increase in adjacent channel selectivity.

10. The method according to any one of claims 7 to 9, the method comprising: performing the step of identifying the preferred center frequency of the at least one channel filter in response to at least one of: a predefined time interval; a power of a received signal being higher than a predetermined level; a signal-to-interference-plus-noise ratio; and an indication that the apparatus performing the method is moving at a speed above a predetermined speed.

11. A computer program product, the computer program product comprising instructions which, when executed by a processor on a device, are configured to control the device to perform the method according to any one of claims 7 to 10.

12. An apparatus for channel filtering, comprising: at least one channel filter for filtering a received wireless communication signal, the at least one channel filter passing signals within a predefined bandwidth and attenuating signals outside the predefined bandwidth; circuitry configured to identify a preferred center frequency for the at least one channel filter, the circuitry configured for identification comprising: A circuit system configured to adjust an effective center frequency of the at least one channel filter; A circuit system configured to determine a level of adjacent channel selectivity of a signal filtered by the at least one channel filter; A circuit system configured to compare levels of adjacent channel selectivity of the at least one channel filter at different center frequencies and identify the preferred center frequency as the center frequency that provides the highest level of adjacent channel selectivity; and A circuit system configured to control, the circuit system configured to control in response to receiving a network signal indicating that an irregular bandwidth channel not corresponding to the bandwidth of the at least one channel filter is supported by the network to: Select one channel filter among the at least one channel filter having a bandwidth wider than the at least one irregular bandwidth; and to Trigger the circuit system configured to identify to identify a preferred center frequency of the selected channel filter, Wherein the circuit system configured to adjust is configured to adjust the effective center frequency to different center frequencies by: Increasing the effective center frequency by an amount equal to half of a difference between the bandwidth of the selected channel filter and the irregular bandwidth; and Decreasing the effective center frequency by the amount.

13. An apparatus for channel filtering, comprising: At least one processor; And At least one memory storing instructions that, when executed by the at least one processor, cause the apparatus to at least perform: Identifying a preferred center frequency of at least one channel filter for filtering a received wireless communication signal by: Adjusting an effective center frequency of the at least one channel filter; Determining a level of adjacent channel selectivity of a signal filtered by the at least one channel filter; Comparing levels of adjacent channel selectivity of the at least one channel filter at different center frequencies; And Identifying the preferred center frequency as the center frequency that provides the highest level of adjacent channel selectivity; And In response to receiving a network signal indicating that an irregular bandwidth channel not corresponding to the bandwidth of the at least one channel filter is supported by the network: Selecting one channel filter among the at least one channel filter having a bandwidth wider than the irregular bandwidth channel; And Initiating the identifying step to identify a preferred center frequency of the selected channel filter, Wherein the step of adjusting the effective center frequency to different center frequencies includes: Increasing the effective center frequency by an amount equal to half of a difference between the bandwidth of the selected channel filter and the irregular bandwidth channel; And Decreasing the effective center frequency by the amount.

Images