WO2016190804A1 - Channel information reporting - Google Patents

Abstract

Methods and apparatus for a wireless device and network node are disclosed. A network node determines at least two or more channel quality tables and configures a wireless device with these ate least two tables. The wireless device selects one out of the at least two channel quality tables for estimating the channel quality wherein the selecting is based on a criterion. The wireless device may report the result of a channel quality estimation and may report an indication of the selected channel quality table.

Description

Channel Information Reporting

TECHNICAL FIELD

The technical filed relates to configuration of channel quality information reporting. BACKGROUND

3^rd Generation partnership project (3GPP) Long Term Evolution (LTE) represents the project within the third generation partnership project, with an aim to improve the Universal Mobile Telecommunications System (UMTS) standard. 3GPP LTE radio interface offers high peak data rates, low delays and increase in spectral efficiencies. LTE ecosystem supports both Frequency division duplex (FDD) and Time division duplex (TDD). This enables the operators to exploit both the paired and unpaired spectrum since LTE has flexibility in bandwidth as it supports 6 bandwidths 1 .4 MHz, 3MHz, 5 MHz, 10 MHz, 15 MHz and 20 MHz.

The LTE physical layer is designed to achieve higher data rates, and is facilitated by turbo coding/decoding, and higher order modulations (up to 64-Quadrature Amplitude Modulation (QAM)). The modulation and coding is adaptive, and depends on channel conditions. Orthogonal frequency division multiple access (OFDMA) is used for the downlink, while Single carrier frequency division multiple access (SC-FDMA) is used for the uplink. The main advantage of such schemes is that the channel response is flat over a sub-carrier even though the multi-path environment could be frequency selective over the entire bandwidth. This reduces the complexity involved in equalization, as simple single tap frequency domain equalizers can be used at the receiver. OFDMA allows LTE to achieve its goal of higher data rates, reduced latency and improved capacity/coverage, with reduced costs to the operator. The LTE physical layer supports Hybrid automatic repeat request (H-ARQ), power weighting of physical resources, uplink power control, and Multiple-Input Multiple Output (MIMO).

3GPP LTE provides several different variations on MIMO techniques, from beamforming to spatial multiplexing or single antenna schemes through selection of one of 10 Transmission Modes (TMs). Some example TMs are explained below. • Transmission mode 3: Open Loop Spatial Multiplexing with Cyclic Delay Diversity and Open Loop Transmit Diversity. This mode is also called open loop single user MIMO. As an open loop mode, this requires no Precoding Matrix Indicator (PMI) but only rank is adapted. Due to its simplicity, this is the widely deployed mode during the initial deployments of 3GPP LTE.

• Transmission mode 4: Closed Loop Spatial Multiplexing (SU MIMO for rank 2 to 4). This has been the primary configuration for the majority of initial Release 8/9 deployments, operating while the channel has rank 2 to 4. It multiplexes up to four layers onto up to 4 antennas. To allow the UE to estimate the channels needed to decode multiple streams, the eNodeB transmits Common Reference Signals (CRS) on prescribed Resource Elements. The UE replies with the Precoding Matrix Indicator (PMI) indicating which precoding is preferred from the pre-defined codebook. This is used for Single User, SU-MIMO. When the UE is scheduled, a precoding matrix is selected and the UE is informed explicitly or implicitly which precoding matrix was used for the actual Physical Downlink Shared Channel (PDSCH) transmission.

• Transmission mode 6: Closed Loop Rank 1 Precoding. This mode uses PMI feedback from the UE to select the preferred (one layer) codebook entry (precoding vector) from the pre-defined rank 1 codebook. Since only rank 1 is used, beamforming gain is expected in this mode but no spatial multiplexing gain.

• Transmission mode 9: 8 layer multiuser (MU)-MIMO, Introduced in Release 10, as part of LTE-Advanced, TM9 implements 2, 4 or 8 reference signals for measurements (CSI-RS) as well as 1 to 8 UE specific reference signals for demodulation (DMRS). Hence, it is a generalization of TM8 for up to 8 layer transmission and the introduction of CSI-RS enhances the CSI feedback. It is suitable for MU-MI O with dynamic switching from SU-MIMO. It is applicable to either TDD or FDD systems and it is mandatory for terminals of Release 10 or later.

Fig. 1 shows a typical message sequence chart for downlink data transfer in LTE. From a pilot or reference signals, the UE computes the channel estimates then computes the parameters needed for channel state information (CSI) reporting. The CSI report consists of for example channel quality indicator (CQI), precoding matrix index (PMI), rank information (Rl). The CSI report is sent to the eNodeB via a feedback channel either Physical Uplink Control Channel (PUCCH) for periodic CSI reporting or PUSCH for aperiodic reporting. The eNodeB scheduler uses this information in choosing the parameters for scheduling of this particular UE. The eNodeB sends the scheduling parameters to the UE in the downlink control channel called PDCCH. After that actual data transfer takes place from eNodeB to the UE.

In LTE, the uplink control channel carries information about HARQ-ACK information corresponding to the downlink data transmission, and channel state information. The channel state information typically consists of Rl , CQI, and PMI . Either PUCCH or PUSCH can be used to carry this information. Note that the PUCCH reporting is periodic and the periodicity of the PUCCH is configured by the higher layers, while the PUSCH reporting is aperiodic. Also note that there are various modes for PUCCH and PUSCH and in general it depends on the transmission mode and the formats is configured via higher layer signaling.

For reporting CQI for each codeword, either of the following CQI tables as shown in Table 1 and 2 are used.

Table 1 : 4-bit CQI Table without 256 QAM

Where Table 1 corresponds to the CQI entries up to 64 QAM and Table 2 corresponds to the CQI entries up to 256-QAM. Note that in LTE the higher layer message (e.g. Radio Resource control) configures the UE which CQI table to be used.

Table 2: 4-bit CQI Table with 256 QAM

In LTE, the downlink control channel (PDCCH) carries information about the scheduling grants Typically this consist of number of MI O layers scheduled, transport block sizes, modulation for each codeword, parameters related to HARQ, sub band locations and also PMI corresponding to that sub bands.

Downlink reference signals are predefined signals occupying specific resource elements within the downlink time-frequency grid. The LTE specification includes several types of downlink reference signals that are transmitted in different ways and used for different purposes by the receiving terminal:

• Cell-specific reference signals (CRS): These reference signals are transmitted in every downlink subframe and in every resource block in the frequency domain, thus covering the entire cell bandwidth. The cell-specific reference signals can be used by the terminal for channel estimation for coherent demodulation of any downlink physical channel except for PMCH and for PDSCH in the case of transmission modes 7, 8, or 9 [1]. The cell-specific reference signals can also be used by the terminal to acquire channel-state information (CSI). Finally, terminal measurements on cell-specific reference signals are used as the basis for cell- selection and handover decisions.

• Demodulation reference signals (DM-RS): These reference signals also sometimes referred to as UE-specific reference signals, are specifically intended to be used by terminals for channel estimation for PDSCH in the case of transmission modes 7, 8, 9 or 10. The label "UE-specific" relates to the fact that each demodulation reference signal is intended for channel estimation by a single terminal. That specific reference signal is then only transmitted within the resource blocks assigned for PDSCH transmission to that terminal.

• CSI reference signals (CSI-RS): These reference signals are specifically intended to be used by terminals to acquire channel-state information (CSI) in the case when demodulation reference signals are used far channel estimation. CSI- RS have a significantly lower time/frequency density, thus implying less overhead, compared to the cell-specific reference signals.

Other than these reference signals, there are other reference signals namely MBSFN reference signals and positioning reference signals used various purposes.

In 3GPP Release 12, 256-QAM was added as an additional modulation scheme and new UE category is defined which can support 256 QAM transmissions. However, from 3GPP RAN4 point of view, which deals with radio performance and RF aspects, currently the support of 256-QAM is limited to small cell scenarios i.e. defined for low power nodes (LPN) aka small or lower power base stations, which serve small cells. Examples of small cells are pico cell, micro cell, femto cell etc. Examples of low power nodes are local area node, medium range node, home or femto base station etc. In addition, a wide area base station may interchangeably and more generally be called a high power node (LPN) or macro base station and a wide area BS may serve a macro cell. At present 3GPP RAN4 is discussing the support of 256-QAM for wide area base stations.

SUMMARY

As mentioned above, the eNode B configures the UE on which CQI table to be used for CQI reporting using higher layer message. In the conventional method, the eNode B may configure the UE based on its capability to support 256-QAM or not. That is if the UE is capable of receiving the 256-QAM transmission from eNode B, the CQI table 2 may configured by the eNode B, otherwise CQI table 1 is configured. However, configuring CQI reporting table based only on the capability is inefficient. For example consider a scenario when the UE (256-QA capable) is at the cell edge. Then in these cases, the UE may benefit from more entries corresponding to QPSK. It can be observed from Table 1 and 2 that QPSK entries for Table 1 are 6 and in Table 2 are 3. If the eNode B configures the UE based only on the capability the UE has to choose few entries from the CQI table 2. In these cases the spectral efficiency loss defined as the difference between the successive spectral efficiencies in the CQI table would be severe. The spectral efficiency loss is predominant at lower CQI indices for CQI table 2 than 2. This reduction in spectral efficiency reduces achievable link and system throughput.

A method is to select and configure one of the at least two CQI tables based on one or more performance criteria. Examples of performance criteria are transmission mode, the geometry of the channel, number of BS transmit and/or UE receive antennas, feedback reporting mode, UE recommendation and other performance related measures such as UE radio environment. The method may be implemented in a UE or in a network node such as the BS.

The UE can select one of the plurality of CQI tables based on one or more criteria (e.g. signal quality threshold) and use the selected CQI table for estimating and reporting the CQI to the network node.

As described herein CSI may also be referred to as CQI or channel quality. E.g. a CSI table could also be referred to as a CQI table or a channel quality table.

A method for a wireless device comprises receiving from a network node information about at least two channel quality tables for estimating a channel quality. The method further comprises selecting one out of the at least two channel quality tables for estimating the channel quality wherein the selecting is based on a criterion.

A method for a network node comprises selecting based on one or more criteria two or more channel quality tables to be used by a wireless device for estimating a channel quality. The method further comprises configuring the wireless device with the at least two selected channel quality tables for use by the wireless device for estimating the channel quality.

A wireless device comprises means for receiving from a network node information about at least two channel quality tables for estimating a channel quality. The wireless device further comprises means for selecting one out of the at least two channel quality tables for estimating the channel quality wherein the selecting is based on a criterion. A network node comprises means for selecting based on one or more criteria two or more channel quality tables to be used by a wireless device for estimating a channel quality. The network node further comprises means for configuring the wireless device with the at least two selected channel quality tables for use by the wireless device for estimating the channel quality.

The methods and apparatuses enable accurate link adaptation thereby minimizing the spectral efficiency loss.

The methods and apparatuses ensure that the higher order modulation (e.g. 256 QAM) can be more efficiently used in a High power node (HPN), macro base station or network node such as a base station.

The methods and apparatuses ensure that the higher order modulation (e.g. 256 QAM) can be used at the HPN, macro base station or network node such as a base station whenever the UE has an opportunity to experience higher SNR or SINR e.g. 20 dB or more.

The methods and apparatuses enhances overall UE and system throughput. BRIEF DESCRIPTION OF DRAWINGS

Figure 1 : Shows a signaling diagram between a network node and a wireless device

Figure 2: Shows a signaling diagram between a network node and a wireless device

Figure 3: Shows a method for a wireless device

Figure 4: Shows a signaling diagram between a network node and a wireless device

Figure 5: Shows a method for a wireless device

Figure 6: Shows a signaling diagram between a network node and a wireless device

Figure 7: Shows a method for a wireless device

Figure 8: Shows a method for a network node

Figure 9: Shows a signaling diagram between a network node and a wireless device

Figure 10a-10c: Shows a wireless device

Figure 1 1 a-10c: Shows a network node DETAILED DESCRIPTION

The terminology such as network node, base station, NodeB, evolved NB or eNB and UE should be considering non-limiting and does in particular not imply a certain hierarchical relation between the two; in general "NodeB" could be considered as device 1 and "UE" device 2, and these two devices communicate with each other over some radio channel. A term network node is used in some embodiments. The network node may be a base station, relay, access point, radio network controller (RNC), base station controller (BSC), NodeB or eNode B etc. A term wireless device is used in some embodiments. The wireless device may be any type of UE such as device-to-device (D2D) UE, machine type communication (MTC) UE etc. Yet another term, radio node, may be used in some embodiments. The radio node may be a network node or a wireless device. In some embodiment several radio nodes may be used e.g. first radio node, second radio node, third radio node etc. The first radio node transmits signals to the second radio node. For example the first and the second radio nodes may be a base station and UE respectively or vice versa. The third radio node may be neighboring to or connected to the second radio node.

Herein, the focus is on wireless transmissions in the downlink, but the embodiments described in here are equally applicable in the uplink. Furthermore, the embodiments described in here are applicable for any wireless system, in particular for future 5G systems. The reason is that the changes in signal to noise ratio (SNR) or signal to interference and noise ratio (SINR) can be very abrupt for 5G. There is only sharp beamforming due to rapid delay of signal. For example at 20-30 GHz or above a minor object between UE and access node (e.g. walking person) can lead to severe loss. So there is not enough time for the UE to send recommendation to the NW and reconfigure the table. It is thus better for the UE to take decision for selection of a channel quality table based on a defined criteria like signal quality. In one example the UE recommends 256-QAM only when the SINR or SNR or an equivalent measure is greater than e.g. 20 dB.

Fig. 2 shows an example of message sequence chart with higher layer signaling. Initially the eNB configures the UE with two or more CQIs table using a message (e.g. higher layer signaling such as RRC or MAC). The eNB can periodically checks the selection criteria for the CQI table and if it is determined based on the criteria that any of the configured CQI table is to be changed then the eNode B sends a message (e.g. using higher order signaling such as RRC or MAC) to the UE to use another CQI table for selecting the most appropriate CQI table for CQI determination (see section on UE procedure). Two or more CQI tables can be pre-defined and the eNB may signal the pre-defined identifiers of the CQI tables to be used by the UE. Therefore when any of pre-configured CQI tables used by the UE is determined to be changed then the eNB may typically send an identifier of the new table to be used by the UE.

The embodiments are described with examples to explain the method of selecting one out of the two pre-defined CQI tables. The embodiments are however applicable for any number of CQI tables. Furthermore the embodiments are also applicable for selecting and using any type of channel state indicator (CSI) table where CQI table is a particular example of CSI reporting metric.

The embodiments are described with focus on 256QAM in the base station. However the embodiments including the criteria for selecting the CSI table are applicable for any type of higher order modulation. A higher order modulation is the one with modulation order above a threshold e.g. 256 QAM. Other examples of higher order modulation are 512QAM, 1024QAM, 2048QAM etc. The modulation order may also interchangeably called as modulation format, modulation type etc.

It is assumed that multiple CSI tables are pre-defined or available and out of which the network node selects and configure two or more CSI tables at the UE. The network node uses one or more performance related primary criteria for determining the most appropriate CQI tables for the UE under the given scenario. The network node uses one or more primary criteria for determining the at least two CQI tables for the UE.

After determining one or more criteria the network node based on a primary criteria, e.g. determined primary criteria, selects the most appropriate CSI tables for a UE, and configure or reconfigure the UE with the selected CSI tables to be used by that UE.

The primary criteria may be at least one of maximum BS power, maximum power per UE, scheduling scheme (e.g. maximum data block size that can be scheduled), BS processing resource, BS maximum power dynamic range etc. The UE may then select one of the selected CSI tables based on secondary criteria. After the CSI table is selected by the UE the UE may use the selected table to estimate and report the estimated CSI (e.g. CQI) to the network node.

The 2-step approach for selection of the CSI table for actual CSI reporting from the UE is used for the following reasons:

Motivation for step-1 (network node selects at least two CSI tables):

Network node has more comprehensive knowledge of the scenario e.g. transmission mode used or expected to be used, maximum BS power, maximum power per UE, scheduling scheme (e.g. maximum data block size that can be scheduled), BS processing resource, BS maximum power dynamic range etc. Therefore NW node provides set of CSI tables which are reasonable or appropriate for the CSI reports under given deployment / operating conditions of the network. For example if NW node has higher output power and large power dynamic range then it can serve UEs with data blocks with finer resolution; this is because DL TX power can be adjusted with different and large number of steps with different sizes e.g. 0.5 dB, 1 dB, 5 dB, 6 dB etc....

Motivation for step-2 (UE selects one CSI tables): . Network node is not aware or less aware of dynamic conditions experienced at the UE (e.g. fading, interference etc.). CSI report which influences scheduling should take into account short time and more dynamic aspects including UE internal resource specific characteristics as described below with specific examples;

2. Network node is not aware or less aware of actual receiver used by the UE (e.g. inter-cell interference mitigation receiver, intra-cell interference mitigation receiver, or combination etc.);

3. Network node is not aware of UE intrinsic resource situation:

- Network node is not aware or less aware of processing and memory resources actually or currently available at the UE;

- Network node is not aware of UE battery life or battery status.

4. Due to the above 3 reasons, the UE is allowed to select one of the CSI tables on more dynamic basis e.g. when one or more secondary criteria is met. The selection of the CSI table by the UE based on one or more secondary criteria as described below. The examples of such primary criteria (or performance specific criteria or primary performance criteria) for selecting the appropriate CSI reporting table are:

- Configured Transmission Mode of the UE

- UE Location in the Cell

- Number of Configured Antenna Ports

- Number of Receiving Antennas at the UE

- Geometry of the UE

- Feedback reporting mode

- Frequency band of operation

- Performance of the network node

- Base station transmission power

- Deployment scenario

- Radio environment of the UE

- UE recommendation regarding CQI table

- Combination of criteria

Configured Transmission mode for the UE: As explained in section 2, several transmission modes are defined in LTE. In some transmission modes, the probability of achieving a high SNR greater than 20 dB is almost negligible in a wide area base station (macro) network. In these cases, the network may determine that UE can never report CQI index corresponding to 256-QAM. I n these cases, it may recommend to the UE to switch to CQI Table 1 . For TM3, few UEs achieve SINR greater than 20 dB. In this case the network node will configure the UE with those CSI tables which contain only QPSK and 16 QAM. Note there can be multiple CQI tables with QPKS and 16QAM associated with for example different transport block size.

For TM6, almost 10 % of the UEs can recommend 256-QAM. This is because in Transmission mode 6, only single layer transmission is possible while in TM3/T 4/TM9 multiple layer transmission is possible. It is well known that single layer SINR is greater than any layer SINR in a multi-layer transmission. Hence with single layer transmission there is a high chance that the UE can recommend 256-QAM. In this case the network node will configure the UE with those CSI tables which contain at least 256QAM or when at least one of the CSI table contains at least 256QAM. Location of the UE: One criterion for determining whether to use CQI table 1 or 2 is to identify the location of the UE in the cell. For example when the UE is nearer to the eNode B it may use CQI tables which contain HOM or at least one table contains HOM e.g. like Table 2. This is because at the cell center the UE generally reports a higher modulation. Similarly, when the UE is at the cell edge, the eNode B may instruct the UE to report using CQI Table 1. Note that there are several methods to identify the UE location from eNode B. For example the UE location in the UE may be determined using one or more positioning methods and/or signals measurements used for radio operations. Examples of positioning methods and corresponding measurements are GNSS (e.g. GPS) measurements, enhanced cell ID (E-CID) measurements such as UE or BS Rx-Tx time difference measurements, timing advance (TA), angle of arrival (AoA), OTDOA RSTD etc. Examples of signal measurements used for radio operations are the reported CQIs, measurements used for the mobility such as RSRP and RSRQ measurement reports, etc. The size of the neighbor cell list (NCL) need for the UE may also be an indication whether the UE is at the cell center or not. For example if serving cell RSRP is below a threshold (e.g. -100 dBm) then the eNodeB may assume that the UE is in the cell border.

Number of Configured Transmit Antenna Ports at the eNode B: Another criterion for determining the CQI table is to check the number of transmit antenna ports (transmission side) for the specific UE. For example the probability of achieving SINR greater than 20 dB is high when the UE is configured with at least 4 antenna ports. This is because of the additional transmit diversity or beamforming provided by the antenna elements. Therefore the eNode B chooses CQI tables with HOM or at least one with HOM when it is configured with 4 antenna ports and CQI table 1 when it is configured with less than 4 antennas ports (e.g. 2 antenna ports) to serve the UE. More generally the eNode B chooses CQI tables similar to table 2 when it is configured with number of antenna ports large than or equal to a Tx antenna threshold (e.g. 4 antenna ports) and otherwise chooses CQI table 1 to serve the UE.

Number of Receiver Antennas at the UE: Another criterion for determining the CQI table is to check the number of receiver antenna for the specific UE. The probability of achieving SINR greater than 20 dB is high when the UE is equipped with 4 receiving antennas. This is because of the additional receiver diversity performance gain achieved by the antenna elements. Therefore the eNode B chooses CQI table 2 when the UE is equipped with at least 4 receiving antennas and CQI table 1 when it is equipped with less than 4 receiving antennas (e.g. 2 antennas). In another aspect of this criterion the eNode B chooses CQI table 2 provided the UE capable of 4 or more antennas actually uses at least 4 receiving antennas and CQI table 1 when actually uses less than 4 receiving antennas.

More generally the eNode B chooses CQI table 2 when the UE is equipped with a number of receiving antennas larger than or equal to a receive antenna threshold. In another aspect of this criterion more generally the eNode B chooses CQI table 2 when the UE actually uses the number of receiving antennas larger than or equal to the receive antenna threshold or.

The network node may determine whether the UE is equipped with or is actually using the number of antennas larger than or equal to the receive antenna threshold based on one or more of the following: indication received from the UE, pre-defined specification of the UE and autonomous determination by the eNodeB e.g. based on UE measurement reports, statistics and historical data.

Note that there are many methods to identify the number of receiver antennas, either by manufacture declaration or by another known technique at the eNode B.

Geometry of the UE: One criterion for determining the CQI Table is to determine and use the geometry of the UE for choosing the CQI table for that UE. At low geometries (e.g. lower SINR) the UE prefers to use lower modulation scheme, therefore eNode B uses CQI table 1. At high geometries (e.g. higher SINR) the UE prefers to use a higher modulation scheme as higher data rate may be achieved; therefore eNode B chooses CQI table 2 under higher UE geometry.

Feedback Reporting Mode: In LTE, the eNodeB B may configure the UE to report wideband CQI and/or sub band CQI. Typically sub band CQI for some of the sub bands is better than the wideband CQI. With wideband CQI it is difficult to achieve SINR greater than 20 dB.

Therefore if the UE is configured with wideband CQI reporting only then CQI table 1 is used. If the UE is configured with sub band CQI reporting then CQI table 2 is used. If the UE is configured with wideband and sub band CQI reporting modes then in one example only CQI table 1 can be used for both reporting modes. In one example if the UE is configured with wideband and sub band CQI reporting modes then CQI table 1 and CQI table 2 can be used for the wideband CQI and sub band CQI reporting modes respectively. Frequency band of operation: Performance of the RF front-end and also the radio link depends on the carrier frequency. For example at higher frequencies components such as oscillators, mixers, RF filters, duplexers, diplexers and power amplifiers may exhibit more impairments than in the lower frequencies. The impairements or losses leads to degradation in SINR achieved at the UE. According to another method of this invention the eNB may determine the CQI table based on the frequency band or the carrier frequency used for the DL transmission. For example when UE is operating at lower frequencies (e.g. frequency bands below 1 GHz) then the eNB may use CQI table 2 and when the UE is operating at lower frequencies (e.g. frequency bands below 1 GHz) then the eNB may use CQI table 1 .

Performance of the RF transmitter and receiver: The advantage of using 256QAM over lower modulation schemes depends also on the performance of the transmitter and receiver nodes. According to one method the eNodeB determines which CQI table to be used based on the RF frontend of the eNodeB and/or the UE aka RF architecture or structure. Examples of such implementations are low cost small radio nodes or low cost UEs (such as machine type communication MTC UEs, UE category 0), where it is likely that higher order modulations does not provide any substantial performance gain due to higher RF impairments. The eNB may determine the UE with reduced performance based on one or more of: indication or capability information of the UE received from the UE, pre-defined specification of the UE and autonomous determination by the eNodeB e.g. based on statistics or historical data of the UE measurement reports etc. For example a UE with low cost RF architecture may be configured with CQI table 1.

Base station transmission power: The base station total maximum transmit power even in a wide area base station may vary from one BS implementation to another. For example it may depend on factors such as the coverage area to be served by the BS, number of carriers supported by the BS, number of transmit antennas in the BS etc. Furthermore the BS maximum transmit power available for each UE may further depend on factors such as cell load (e.g. number of UEs in the cell served by the UE etc), frequency band used by the UE etc.

According to this criterion the network node may select the CQI table for a particular UE depending upon the BS total maximum transmit power (Ptotai.max) and/or the BS maximum transmit power available (Pmax,uE) for this particular UE. For example if the Pioiai. max is above or equal to a totat maximum power threshold (e.g. 43 dBm) and/or P^ IIE is above or equal to maximum available power threshold (e.g. 24 dBm) then the network node may decide to use CQI table 2 for this UE; otherwise the network node may decide to use CQI table 1 for this UE.

Deployment scenario: In yet another example the network node may select the CQI table for a particular UE depending upon the deployment scenario in which the UE is operating. Examples of parameters which characterize deployment scenario are cell size of the cell served by the BS (e.g. cell range, cell radius etc), inter-site distance between base stations, homogeneous or heterogeneous network etc.

For example if base station is wide area and cell range is short then the network node may expect the UE close to the UE to experience higher SINR. In this case the network node may choose the CQI table 2 for such UE.

Radio environment: In yet another example the network node may select the CQI table for a particular UE depending upon the radio environment in which the UE is operating. Examples of parameters which characterize radio environment are UE speed (e.g. UE Doppler frequency), multipath delay profile or delay spread, channel delay spread, radio channel coherence BW, shadow fading etc. The BS may determine the radio environment in which the the UE is operating or is expected to operate by measuring one or more of UE Doppler frequency, channel coherence BW, channel coherence time etc.

For example if the radio environment is determined to be highly dispersive (e.g. delay spread larger than 1 μ≤) and/or UE speed is above a threshold (e.g. greater than 5 km/hour) then the network node may choose the CQI table 1 for such UE; otherwise it may use CQI table 2 for this UE.

UE recommendation regarding CQI table: According to yet another example of criteria the network node may also take into account the recommendation about the CQI table to use from the UE.

For example the UE based on one or more measurements (e.g. SINR, BLER, CQI, RSRQ etc) may determine the most appropriate CQI table to be used for estimating the CQI. The most appropriate CQI herein means for example the one which would lead to least number of retransmission of data blocks and/or lowest BLER and/or maximum UE throughput under the given radio conditions. In one example the UE may be configured to send the recommendation periodically e.g. once every radio frame. In another example the UE may be configured to send the recommendation along with every CQI report. In yet another example the UE may be configured to send the recommendation only when the currently used CQI table is to be changed .

In one example the network node may select CQI table based on any UE recommendation . In yet another example the network node may select the UE recommended CQI table only if the UE has repeatedly (e.g. N number of times in a time period) recommended the network node to use the same CQI table. As an example N=4 consecutive recommendations

Any combination of two or more criteria described above may also be used by the eNode B for determining the CQI Table.

According to this embodiment the UE is configured with at least two CSI tables (e.g. CQI tables 1 and 2) as determined by the network node based on one or more primary criteria. The UE is required to estimate and report one type of CSI using one of the configured CSI tables when one or more secondary criteria are met.

The UE performs selection of the CSI tables from the plurality of CSI tables under any one of the following schemes:

1 . Two or more CSI tables are configured by the network node and secondary criteria for selecting CSI table can be determined or decided by the UE itself or can be predefined;

2. Two or more CSI tables as well as the secondary criteria (e.g. thresholds) for selecting the CSI table (from the plurality of CSI tables) are pre-configured at the UE by the network node.

Hereinafter we use the term CQI but description applies to any type of CSI reporting.

The UE regularly evaluates one or more secondary criteria (described further below) and determine the most appropriate CQI table to be used for estimating and reporting the CQI value to the network node. In this case the UE may also signal the identifier of the CQI table being used for estimating and reporting the CQI along with the reported CQI. This enables the network node to unambiguously identify the parameters associated with the UE reported CQI e.g. transport block size, modulation type etc. This in turn allows the network node to select and schedule the UE with the data using the appropriate transport block size. In yet another aspect of this embodiment the UE may be configured with the maximum rate with which the UE is allowed to change the CQI table for estimating and reporting the CQI. The maximum rate specified how often the UE is allowed to change the current CQ table which the UE is using for CQI reporting. For example the UE may be configured not to change the CQI table faster than once per 4 radio frames. This will prevent the UE from ping-pong effect i.e. to avoid UE changes CQI table too fast. The UE may be configured with the maximum rate or corresponding duration over which the same CQI table is to be used based on pre-defined rules and/or information received from the network node.

As stated above the UE may be configured (autonomously or based on information from the network node) with one or more secondary criteria (e.g. signal thresholds), which are to be used by the UE for switching between the at least two pre-configured CQI tables or selecting one of the CQI tables from the plurality of pre-configured CQI tables. Examples of secondary and/or second criteria are:

• Signal thresholds: Examples of the signal threshold are signal quality (e.g. CQI, SINR, SNR, BLER etc.), signal strength (e.g. RSRP, path loss etc.) etc.

• UE receiver type being or expected to use. UE typically has several receivers but uses one or selected set of receivers. Examples of UE receiver types are:

1. Baseline receiver which does not mitigate any interference but only suppresses. Example of baseline receiver is MSE- RC. If UE is using this type of receiver then it may only select CQI table with more robust modulation e.g. QPSK;

2. Interference mitigation receiver:

- Interference rejection receiver (IRC): It can reject interference.

Example of IRC receiver is MMSE-IRC;

Interference cancellation (IC) receiver: It can cancel inter-interference caused by data channel such as PDSCH. Example of IC receiver is maximum likelihood (ML).

- If UE is using any of the above type of receiver then it may select CQI table with less robust modulation e.g. 64 QAM or 256QAM. • Processing resources: Examples are memory, processors etc. UE can dynamically assign or share resources between different features e.g. CQI estimation, application program, music, camera etc.

• UE battery life: For example how much battery is available at the UE. If battery is low (e.g. 25% or less) then the UE may select a CQI table which has more CQI tables of lower order modulation (e.g. QPSK). This is because QPSK is more robust and requires less processing and UE will also be scheduled with smaller data block.

The UE using the signal threshold(s) as the secondary criteria for selection of one of the CQI tables are further described below with several examples.

The UE may further be configured with one or more supplementary parameters associated with the signal thresholds; examples of such supplementary parameters are confidence intervals or probability, minimum signal quality assessment time period (TO). For example the UE may be configured with one or more confidence intervals or probability parameters (corresponding to the signal thresholds) with which the UE needs to meet signal threshold criteria to switch between the CQI tables. Similarly the UE may also be configured with one or more minimum assessment time periods over which the UE is required to assess the signal quality and/or signal strength for switching between the CQI tables. The UE may be configured with one or more signal thresholds and the confidence intervals based on one or more of the following: pre-defined rules, information received from the network node and autonomous selection by the UE. This is explained with few examples below:

1. In one example the UE may be configured with a SINR threshold of 20 dB. If the UE experiences SINR of 20 dB or more then the UE selects CQI table 2 otherwise the UE uses CQI table 1 .

2. In another example the UE may be configured with a SINR threshold of 20 dB as well as confidence interval of 10%. If the UE experiences SINR of 20 dB or more with a probability of 10% or more then the UE selects CQI table 2 otherwise the UE uses CQI table 1.

3. In yet another example the UE may be configured with a SINR threshold of 20 dB, confidence interval of 0% and minimum assessment time period (e.g. TO = 100 ms) of signal quality assessment. If the UE experiences SINR of 20 dB or more with a probability of 10% or more or at least T0= 100 ms only then the UE selects CQI table 2 otherwise the UE uses CQI table 1. 4. In any of the above examples (#1 to #3) the UE may further assess one or more performance related criteria defined in sections 1 .1 -1.11. The UE will select a particular CQ table only if the UE also meets one or more performance criteria for the same CQI table which is also determined based on the signal threshold and supplementary parameters (e.g. confidence interval, minimum assessment time period etc.).

The UE after selecting the CQI table estimates the CQI based on the selected CQI table and reports the estimated CQI to the network node. The UE may also include the identifier of the CQI table in the report especially if the CQI table is changed. Otherwise the network node will assume that the UE has used the same CQI table as used for reporting the previous CQI reports.

In the following several embodiments with respect to a wireless device will be discussed in relation to figs. 3-7. One or more acts act from an exemplary embodiment may be combined, where appropriate, with one or more acts of another exemplary embodiment.

An exemplary method for a wireless device with respect to fig. 3 will now be discussed. The method comprises receiving A1 from a network node information about at least two channel quality tables for estimating a channel quality. The method further comprises selecting A2 one out of the at least two channel quality tables for estimating the channel quality wherein the selecting is based on a criterion.

The act of receiving A1 may comprise any suitable way of communicating information from network node to a wireless device. For example, if a quick adaptation lower and/or layer 1 signaling may be used for indicating the selected channel quality tables. One example may be to use a downlink control information and/or indicator, DCI. If a less quick adaptation is wanted radio resource control, RRC, signaling may be used. This may include using an RRC message where the selected channel quality tables may be added to an already defined message in the standard or using an RRC message that may be newly defined. Another alternative is to broadcast a larger set of channel quality tables and then individually indicate the selected channel quality tables to each wireless device using either lower and/or layer 1 signaling or RRC signaling. The information may also be received as described in relation to fig. 3. The act of selecting A2 may comprise selecting using any of the criterions described as a secondary and/or second criteria herein. For example the, secondary and/or second criteria may be one or more of a signal value at the wireless device in relation to a signal threshold, the type of receiver used by the wireless device, the amount of available processing resources in the wireless device and the remaining battery life of the wireless device.

The method as described in relation to fig. 3 may further comprise reporting, A5 information of the selected channel quality table to the network node. This may be achieved as described above using an identifier of the channel quality table being used. As with the information being sent to the wireless device, the wireless device may indicate the selected channel quality table using e.g. if a quick adaptation lower and/or layer 1 signaling may be used for indicating the selected channel quality table. One example may be to use a scheduling request. If a less quick adaptation is wanted radio resource control, RRC, signaling may be used. This may include using an RRC message where the selected table may be added to an already defined message in the standard or using an RRC message that may be newly defined.

The method as described in relation to fig. 3 may further comprise estimating A3 the channel quality using the selected channel quality table. The estimation may be performed with respect to the same network node or a different network node than where the information on CSI table is received from.

The method as described in relation to fig. 3 may further comprise reporting A4 the results of the estimated channel quality to the network node. The reporting of the result of the estimated channel quality may be reported in the same way as the selected channel quality table is reported to the network node of act A5.

The method as described in relation to fig. 3 may also be seen from the perspective a signaling diagram as seen in fig. 4. Arrows indicates information being exchanged between the nodes while a box indicates an internal act which may or may not include receiving additional information and/or signals to perform the act. The references A1-A5 corresponds to A1-A5 as described above.

An exemplary method for a wireless device with respect to fig. 5 will now be discussed.

The method comprises receiving B1 from a network node information about at least two CSI tables for estimating the CSI. The information may be received in the same way as for act A1 . The method further comprises obtaining B2 at least one secondary criterion e.g. signal threshold (e.g. SINR = 20 dB). Obtaining may include receiving the secondary criterion from the network node or network or having the secondary criterion predefined in the UE. The information regarding the secondary criterion may be received in the same way as for act A1 . Alternatively the secondary criterion is preconfigured in the wireless device.

The method further comprises estimating B3 signal quality on a radio signal received from a network node. The estimation may be performed in the same way as act A3.

The method further comprises comparing B4 the estimated signal quality with the second criterion. The second criteria may be any of the criterions described herein as a secondary and/or second criteria.

The method further comprises selecting B5 based on the comparison one out of the at least two CSI tables for estimating the CSI (e.g. CQI).

The method may further comprise estimating B6 the CSI using on the selected CSI table. The estimation may be performed in the same way as act A3.

The method may further comprise reporting B7 the results of the estimated CSI to the network node. The reporting of the result of the estimated channel quality may be reported in the same way as the selected channel quality table is reported to the network node as described with respect to act A5 .

The method may further comprise transmitting B8 information about the selected CSI table to the network node. The transmission may be done in the same way as described in act A5.

The method as described in relation to fig. 5 may also be seen from the perspective a signaling diagram as seen in fig. 6. Arrows indicates information being exchanged between the nodes while a box indicates an internal act which may or may not include receiving additional information and/or signals to perform the act. The references B1-B8 corresponds to B1-B8 as described above. An exemplary method for a wireless device with respect to fig. 7 will now be discussed.

The method comprises determining C1 a deployment scenario in which the wireless device is operating and select a CSI table based on the determined deployment scenario. The method further comprises estimating C2 a CSI based on the determined deployment scenario. The estimation may be performed in the same way as act A3. The method further comprises reporting C3 the results of the estimated CSI. The reporting may be performed in the same way as act A5.

In some embodiments the deployment scenario may be a cell radius or a cell range or cell size of a cell covered by a network node. Said deployment scenario may be an inter- site distance between base stations or a distance to a neighboring or adjacent network node from the network node. In some embodiments the deployment scenario is indicated to the wireless device via signaling from a network node.

An exemplary method for a network node with respect to fig. 8 will now be discussed.

The method comprising selecting D1 based on one or more criteria two or more channel quality tables to be used by a wireless device for estimating a channel quality. The method further comprises configuring D2 the wireless device with the at least two selected channel quality tables for use by the wireless device for estimating the channel quality. The method may further comprise receiving D3 from the wireless device an estimated channel quality based on the configured channel quality tables. Optionally the network node may also receive D4 an indication of a channel quality table as selected by the wireless device.

Selecting two or more channel quality tables based one or more primary criterions may be based on any of the primary criteria as described above. The selection may also be performed as described above in relation to the primary criteria.

Configuration of the wireless device with at least two selected channel quality tables may be performed in the corresponding way as act A1 . The acts of D3 and D4 may be performed in a corresponding way as acts A4 and A5.

The method as described in relation to fig. 8 may also be seen from the perspective a signaling diagram as seen in fig. 9. Arrows indicates information being exchanged between the nodes while a box indicates an internal act which may or may not include receiving additional information and/or signals to perform the act. The references D1 -D4 corresponds to D1-D4 as described above. The methods and techniques described above may be implemented in wireless devices and/or network nodes. Above, in association with describing the method embodiments, it is exemplified in which nodes in an LTE system the methods are intended to be implemented. Corresponding nodes in other communication systems may be denoted differently.

An exemplifying embodiment of a wireless device, such as the one exemplified as a UE, and denoted "UE" above, is illustrated in a general manner in fig. 10a. The wireless device will here be denoted UE, as an example. The UE 1000 is configured to perform at least one of the method embodiments described above, e.g. with reference to any of figs. 2-7 and/or the methods for wireless device described herein. The UE 1000 is associated with the same technical features, objects and advantages as the previously described method embodiments. The UE will be described in brief in order to avoid unnecessary repetition.

The UE may be implemented and/or described as follows. The UE is exemplified in correspondence with fig. 3 but is possible to have the UE implemented for the other embodiments and/or figs. e.g. fig. 5 or 7 with the proper modifications of the UE so as to perform the described methods.

The UE 1000 comprises processing circuitry 1001 and a communication interface 1002. The processing circuitry 1001 is configured to receive from a network node information about at least two channel quality tables for estimating the channel quality. The processing circuitry 1001 is further configured to, select and/or determine one out of the at least two channel quality tables for estimating the channel quality wherein the selecting is based on a criterion such as a second criteria. The communication interface 1002, which may also be denoted e.g. Input/Output (I/O) interface, includes a network interface for sending data or information to and receiving data or information from other network nodes.

The processing circuitry 1001 could, as illustrated in fig. 10b, comprise processing means, such as a processor 1003, e.g. a CPU, and a memory 1004 for storing or holding instructions. The memory would then comprise instructions, e.g. in form of a computer program 1005, which when executed by the processing means 1003 causes the UE 1000 to perform the actions, methods and/or acts described herein. An alternative implementation of the processing circuitry 1001 is shown in fig. 10c. The processing circuitry here comprises a receiving unit 1006, configured to cause the UE to receive from a network node information about at least two channel quality tables for estimating the channel quality. The processing circuitry further comprises a selection unit 1007, configured to cause the UE to, select or determine one out of the at least two channel quality tables for estimating the channel quality wherein the selecting is based on a second criterion. The processing circuitry may further comprises a reporting unit 1008, configured to cause the UE to, report the results of the estimated channel quality wherein the report may be sent to the network node and maybe also information about the selected channel quality table to the network node.

The UE 1000 may be assumed to comprise further functionality, for carrying out regular UE functions.

An exemplifying embodiment of a network node or base station is illustrated in a general manner in fig. 1 1a. The network node 1 100 is configured to perform at least one of the method embodiments described above, e.g. with reference to fig. 8 and/or the methods for network node described herein. The network node 1100 is associated with the same technical features, objects and advantages as the previously described method embodiments. The network node will be described in brief in order to avoid unnecessary repetition.

The network node may be implemented and/or described as follows. The network node is exemplified in correspondence with fig. 8 but is possible to have the network node implemented for the other embodiments with the proper modifications of the network node so as to perform the described methods.

The network node 1 100 comprises processing circuitry 1 101 and a communication interface 1 102. The processing circuitry 1 101 is configured to select based on one or more primary criteria two or more channel quality tables to be used by a UE for estimating the channel quality. The processing circuitry 1 101 is further configured to configure the UE with the at least two selected channel quality tables for use by the UE for estimating the channel quality. The processing circuitry 1 101 is further configured to receive from the UE results of the UE estimated channel quality based on the configured channel quality table. The processing circuitry 1 101 may further configured to receive from the UE an indication of a channel quality table as selected by the UE. The communication interface 1102, which may also be denoted e.g. Input/Output (I/O) interface, includes a network interface for sending data to and receiving data from other network nodes. The processing circuitry 1 101 could, as illustrated in fig. 1 1 b, comprise processing means, such as a processor 1 103, e.g. a CPU, and a memory 1104 for storing or holding instructions. The memory would then comprise instructions, e.g. in form of a computer program 1 105, which when executed by the processing means 1 103 causes the network node 1100 to perform the actions described above.

An alternative implementation of the processing circuitry 1 101 is shown in fig. 11 c. The processing circuitry here comprises a selecting unit 1 106, configured to select based on one or more primary criteria two or more channel quality tables to be used by a UE for estimating the channel quality. The processing circuitry further comprises a configuring unit 1 107, configured to configure the UE with the at least two selected channel quality tables for use by the UE for estimating the channel quality. The processing circuitry further comprises a receiving unit 1 08 configured to receive from the UE results of the UE estimated channel quality based on the configured channel quality table. The receiving unit 1 108 may also be configured to receive from the UE an indication of a channel quality table as selected by the UE.

The network node described above could be configured for the different method embodiments described herein.

The network node 00 may be assumed to comprise further functionality, for carrying out regular network node functions.

The steps, functions, procedures, modules, units and/or blocks described herein may be implemented in hardware using any conventional technology, such as discrete circuit or integrated circuit technology, including both general-purpose electronic circuitry and application-specific circuitry.

Particular examples include one or more suitably configured digital signal processors and other known electronic circuits, e.g. discrete logic gates interconnected to perform a specialized function, or Application Specific Integrated Circuits (ASICs).

Alternatively, at least some of the steps, functions, procedures, modules, units and/or blocks described above may be implemented in software such as a computer program for execution by suitable processing circuitry including one or more processing units. The software could be carried by a carrier, such as an electronic signal, an optical signal, a radio signal, or a computer readable storage medium before and/or during the use of the computer program in the network nodes. At least part of the network nodes described above may be implemented in a so-called cloud solution, referring to that the implementation may be distributed, and the network nodes therefore may be so-called virtual nodes or virtual machines.

The flow diagram or diagrams presented herein may be regarded as a computer flow diagram or diagrams, when performed by one or more processors. A corresponding apparatus may be defined as a group of function modules, where each step performed by the processor corresponds to a function module. In this case, the function modules are implemented as a computer program running on the processor.

Examples of processing circuitry includes, but is not limited to, one or more microprocessors, one or more Digital Signal Processors, DSPs, one or more Central Processing Units, CPUs, and/or any suitable programmable logic circuitry such as one or more Field Programmable Gate Arrays, FPGAs, or one or more Programmable Logic Controllers, PLCs. That is, the units or modules in the arrangements in the different nodes described above could be implemented by a combination of analog and digital circuits, and/or one or more processors configured with software and/or firmware, e.g. stored in a memory. One or more of these processors, as well as the other digital hardware, may be included in a single application-specific integrated circuitry, ASIC, or several processors and various digital hardware may be distributed among several separate components, whether individually packaged or assembled into a system-on-a- chip, SoC.

It should also be understood that it may be possible to re-use the general processing capabilities of any conventional device or unit in which the proposed technology is implemented. It may also be possible to re-use existing software, e.g. by reprogramming of the existing software or by adding new software components. The embodiments described above are merely given as examples, and it should be understood that the proposed technology is not limited thereto. It will be understood by those skilled in the art that various modifications, combinations and changes may be made to the embodiments without departing from the present scope. In particular, different part solutions in the different embodiments can be combined in other configurations, where technically possible.

It should be noted that although terminology from 3GPP LTE has been used in this disclosure to exemplify the invention, this should not be seen as limiting the scope of the invention to only the aforementioned system. Other wireless systems which support a broadcast service may also benefit from exploiting the ideas covered within this disclosure.

When using the word "comprise" or "comprising" it shall be interpreted as non- limiting, i.e. meaning "consist at least of.

It should also be noted that in some alternate implementations, the functions/acts noted in the blocks may occur out of the order noted in the flowcharts. For example, two blocks shown in succession may in fact be executed substantially concurrently or the blocks may sometimes be executed in the reverse order, depending upon the functionality/acts involved. Moreover, the functionality of a given block of the flowcharts and/or block diagrams may be separated into multiple blocks and/or the functionality of two or more blocks of the flowcharts and/or block diagrams may be at least partially integrated. Finally, other blocks may be added/inserted between the blocks that are illustrated, and/or blocks/operations may be omitted without departing from the scope of inventive concepts.

It is to be understood that the choice of interacting units, as well as the naming of the units within this disclosure are only for exemplifying purpose, and nodes suitable to execute any of the methods described above may be configured in a plurality of alternative ways in order to be able to execute the suggested procedure actions.

It should also be noted that the units described in this disclosure are to be regarded as logical entities and not with necessity as separate physical entities.

Abbreviation Explanation

MI O Multiple input multiple output Tx Transmitter

UE User Equipment

BS Base Station

eNB Evolved Node B, base station

E-UTRA Evolved universal terrestrial radio access network

E-UTRA Evolved universal terrestrial radio access

E-UTRA FDD E-UTRA frequency division duplex

E-UTRA TDD E-UTRA time division duplex

LTE Long term evolution

RAT Radio Access Technology

SINR Signal-to-interference Ratio

RSRQ Reference signal received quality

RSRP Reference signal received power

CSI Channel state information

LPN Low power node

HPN High power node

Claims

1 . A method for a wireless device, the method comprising:

- receiving (A1) from a network node information about at least two channel quality tables for estimating a channel quality; and selecting (A2) one out of the at least two channel quality tables for estimating the channel quality wherein the selecting is based on a criterion.

2. The method according to claim 1 , the method further comprising reporting (A5) information of the selected channel quality table to the network node.

3. The method according to any of claims 1 -2, the method further comprising

estimating (A3) the channel quality using the selected channel quality table.

4. The method according to any of claim 3, the method further comprising reporting (A4) the results of the estimated channel quality to the network node.

5. The method according to any of claims 1 -4, wherein the criterion is a signal

threshold.

6. The method according to any of claims 1 -4, wherein the criterion is one or more of a signal value at the wireless device in relation to a signal threshold, the type of receiver used by the wireless device, the amount of available processing resources in the wireless device and the remaining battery life of the wireless device.

7. A method for a network node, the method comprising: selecting (D1) based on one or more criteria two or more channel quality tables to be used by a wireless device for estimating a channel quality; and configuring (D2) the wireless device with the at least two selected channel quality tables for use by the wireless device for estimating the channel quality.

8. The method according to claim 7, the method further comprising receiving (D3) from the wireless device an estimated channel quality based on the configured channel quality tables.

9. The method according to any of claims 7 or 8, the method further comprising

receiving (D4) an indication of a channel quality table as selected by the wireless device.

10. The method according to any of claims 7-9, wherein the one or more criteria is at least on of

- a configured transmission mode of the wireless device

a geographical location of the wireless device in a cell

a number of configured antenna ports at the network node

- a number of receiving antennas at the wireless device

a geometry of the wireless device

- a feedback reporting mode of the wireless device

- a frequency band of operation for communication with the wireless device

- a transmission power of the network node

a deployment scenario in which the wireless device is operating

- a radio environment of the wireless device

- a recommendation from the wireless device regarding a channel quality table

1 1. A wireless device (1000), the wireless device comprising:

- means for receiving (1002, 1006) from a network node (1100) information about at least two channel quality tables for estimating a channel quality; and

- means for selecting (1001 , 1007) one out of the at least two channel quality tables for estimating the channel quality wherein the selecting is based on a criterion.

12. The wireless device (1000) according to claim 11 , the wireless device (1000) further comprising means for reporting (1002, 1008) information of the selected channel quality table to the network node (1 100).

13. The wireless device (1000) according to any of claims 1 1 -12, the wireless device (1000) further comprising means for estimating (1001 ,1010) the channel quality using the selected channel quality table.

14. The wireless device (1000) according to any of claim 13, the wireless device (1000) further comprising means for reporting (1002, 1008) the results of the estimated channel quality to the network node (1 100).

15. The wireless device (1000) according to any of claims 1 1 -14, wherein the criterion is a signal threshold.

16. The wireless device (1000) according to any of claims 1 1 -14, wherein the criterion is one or more of a signal value at the wireless device (1000) in relation to a signal threshold, the type of receiver used by the wireless device ( 000), the amount of available processing resources in the wireless device (1000) and the remaining battery life of the wireless device (1000).

17. A network node (1100) for a network node (1 100), the network node (1100) comprising: means for selecting (1 101 ,1 106) based on one or more criteria two or more channel quality tables to be used by a wireless device (1000) for estimating a channel quality; and

- means for configuring (1 101 ,1 02, 1 107) the wireless device (1000) with the at least two selected channel quality tables for use by the wireless device (1000) for estimating the channel quality.

18. The network node (1100) according to claim 7, the network node (1 100) further comprising means for receiving (1 102, 1 108) from the wireless device (1000) an estimated channel quality based on the configured channel quality tables.

19. The network node (1100) according to any of claims 7 or 8, the network node

(1100) further comprising means for receiving (1 102, 1108) an indication of a channel quality table as selected by the wireless device (1000).

20. The network node (1100) according to any of claims 7-9, wherein the one or more criteria is at least on of

- a configured transmission mode of the wireless device (1000)

- a geographical location of the wireless device (1000) in a cell

a number of configured antenna ports at the network node (1 100)

- a number of receiving antennas at the wireless device ( 000)

- a geometry of the wireless device (1000)

- a feedback reporting mode of the wireless device (1000)

- a frequency band of operation for communication with the wireless device (1000)

- a transmission power of the network node (1100)

a deployment scenario in which the wireless device (1000) is operating

- a radio environment of the wireless device (1000) a recommendation from the wireless device (1000) regarding a chan quality table