HK1238841B - Handling of gaps in use of a radio transceiver - Google Patents

Description

Handling gaps in use of radio transceivers

Technical Field

The present invention relates generally to the field of cellular communications. More particularly, the present invention relates to mitigating the adverse effects of gaps in the use of radio transceivers of wireless communication devices operating in conjunction with a cellular communication network.

Background Art

Typical implementations of wireless communication devices include a radio transceiver shared by one or more radio access control units (eg, software stacks) that control the operation of the wireless communication device in conjunction with a corresponding cellular network.

For various reasons, transmission and/or reception gaps may be enforced during the use of a radio transceiver by a radio access control unit, without the network being aware of the gaps. For example, if a radio transceiver is shared by two radio access control units, one of the radio access control units may autonomously interrupt the use of the radio transceiver by the other radio access control unit (e.g., to perform measurements, listen for paging signals, etc.). Other examples include transmission and/or reception gaps introduced for energy conservation or due to significant interference occurring at a particular time (e.g., from radar operations at an airport).

During transmit and/or receive gaps, there may be various reasons for a network node to increase the robustness of the modulation and coding scheme (MCS) used for downlink transmissions. For example, if a transmit gap occurs, the wireless communication device will not be able to transmit channel condition indication reports (e.g., CQI (Channel Quality Indicator) or CSI (Channel State Information). Alternatively, or additionally, if a transmit gap occurs, the wireless communication device will not be able to transmit HARQ (Hybrid Automatic Repeat Request) ACK/NACK (Acknowledgement/Negative Acknowledgement) messages. Alternatively, or additionally, if a receive gap occurs, the wireless communication device will not be able to receive any data, resulting in the loss of HARQ ACK/NACKs. Alternatively, or additionally, if a receive gap occurs, the wireless communication device will not be able to receive any uplink allocations, resulting in the loss of uplink data in the allocated resources. All of these situations may cause the network to conclude that the channel is poor and, therefore, select a more robust MCS.

However, once a transmit/receive gap ends, the wireless communication device can resume communication under the same (or similar) conditions as before the gap. Therefore, it may not be necessary to apply a more robust MCS that would cause a decrease in throughput. Since the control loop involving channel condition reports from the wireless communication device and corresponding MCS adjustments typically takes some time to converge, a significant reduction in throughput may be experienced. This reduced throughput may impact the wireless device and/or the system as a whole.

The above situation will be further illustrated by the following examples.

FIG. 1 illustrates several scenarios in which transmission and/or reception gaps are autonomously formed by wireless communication devices.

Part a) shows the use 100 of a radio transceiver for UMTS LTE TDD (Universal Mobile Telecommunications Standard, Long Term Evolution, Time Division Duplex) and corresponding transmit (Tx) blanking 101 (i.e., transmit gaps) during a repetition period 102. Part b) also shows the use 110 of a radio transceiver for UMTS LTE TDD and corresponding transmit blanking and receive (Rx) puncturing 111 (i.e., transmit and receive gaps) during a repetition period 112.

In parts a) and b), the configuration shown is UMTS LTE TDD uplink/downlink configuration 1, where Rx puncturing and/or Tx blanking is extended over one radio frame.

Part c) shows the use of radio transceivers 120, 125 for uplink (UL) and downlink (DL) UMTS LTE FDD (frequency division duplex) and corresponding transmit blanking 121 (i.e., transmit gaps) during a repetition period 126. Part d) shows the use of radio transceivers 130, 135 for uplink (UL) and downlink (DL) UMTS LTE FDD and corresponding transmit blanking and receive puncturing (i.e., transmit and receive gaps 131) during a repetition period 132.

Figure 2 shows an example of seven HARQ processes (P1, P2, P3, P4, P5, P6, and P7) on the downlink and the corresponding ACK/NACKs for LTE TDD uplink/downlink configuration 1, as shown in TDD UL/DL allocation 200. For example, as indicated by the downward arrow labeled P1, data packets (transport blocks) for DL process P1 are transmitted (or retransmitted) in subframe 0 of the first repetition period and in subframe 1 of the second repetition period. As indicated by the curved arrow leading from subframe 0 to subframe 7, ACK/NACKs for data packets for DL process P1 transmitted in subframe 0 of the first repetition period are expected in subframe 7 of the first repetition period. White subframes indicate downlink reception, dotted subframes indicate uplink transmission, and striped subframes indicate special subframes. For example, if uplink subframes 7 and 8 are blanked, the network node will not receive any ACK/NACKs for the downlink transport blocks of subframes 0, 1, and 4, even though they may have been successfully received.

As mentioned above, the autonomous interval may cause a network node (eg, eNodeB - eNB in UMTS LTE) to assume that a wireless communication device (eg, user equipment UE in UMTS LTE) is experiencing a poor radio channel.

The eNB may assume that the UE has therefore failed to decode the downlink control information, which itself is more robust than transmissions on the DL-SCH (Downlink Shared Channel).

Alternatively or additionally, the eNB may assume that a previously reported channel quality indicator (CQI) is no longer valid. Thus, the eNB may fall back and assume that the channel quality is lower than the quality indicated by the previously reported CQI.

Alternatively or additionally, the eNB may assume that a particular UE is biased in its CQI reporting and, for example, reports a more favorable quality than according to the actual channel conditions.

The channel quality indicator (CQI) indicates how many information bits can be sent in an allocation of a specific size (e.g., 20 resource block (RB) pairs). At low channel quality (corresponding to a low CQI), more error correction coding and/or lower-order modulation are required for successful transmission of the information bits, while at high channel quality (corresponding to a high CQI), less error correction coding and/or higher-order modulation may be used and still achieve successful transmission of the information bits. Therefore, at a high CQI, the throughput of information bits can be higher than at a low CQI, as shown in the following example table (4-bit CQI table in Section 7.2.3 of 3GPP TS 36.213).

When the eNB makes one or more of the assumptions exemplified above due to not knowing the autonomous gap, it may select a more robust MCS (combination of modulation and coding rate), i.e., an MCS corresponding to a lower CQI index, which impacts throughput as exemplified in the efficiency column of the table above.

Several situations in which gaps occur in the use of a radio transceiver by a radio control unit will be described below.

Paging

Idle wireless communication devices (User Equipment - UE) tune to the corresponding network node (base station) at predetermined times, paging occasions, to check whether they are being paged by the network. The reason for being paged may be, for example, that the UE has an incoming call to receive.

While in idle mode, the UE handles mobility autonomously, using neighbor cell information provided by the network. If the currently camped cell becomes weak and a stronger neighbor cell becomes available, the UE will change camped cell to the stronger neighbor. During this so-called cell reselection, the UE does not monitor for paging, and therefore, if it is paged during this time, the page may be missed. To prevent missed pages due to interruptions caused by cell reselection, the radio access network typically repeats the page one or more times until the UE responds.

All base stations in the so-called location (or tracking) area where the UE is registered are paging the UE. When the UE moves to a cell in another location (or tracking) area, for example due to crossing a geographical boundary or changing to another radio access technology, it updates the network about its location via a location (or tracking) area update procedure. During the time the UE is updating its location (or tracking) area, the radio access network will have outdated information about the areas in which the UE should be paged. To prevent missed pages due to outdated location information, if the UE does not respond to a page in its registered location (or tracking) area, the radio access network typically repeats the page in a neighboring location (or tracking) area.

If the second radio access control unit needs to listen for paging during a paging occasion, a gap may occur in the usage of the radio transceiver by the first radio access control unit.

Paging occasions generally follow a so-called paging cycle configured by the radio access network node. The paging cycle length also depends on the radio access technology. Some example idle mode paging cycles include:

GSM – 471, 706, 942, 1177, 1412, 1648, 1883, 2118 ms

WCDMA – 640, 1280, 2560, 5120 ms

TD-SCDMA – 640, 1280, 2560, 5120 ms

LTE – 320, 640, 1280, 2560 ms

Circuit Switched Fallback (CSFB)

Circuit switched fallback is an interim solution for supporting voice calls to UEs connected to UMTS LTE until VoLTE (Voice over LTE, VoIP) and SRVCC (Single Radio Voice Call Continuity) are supported in the network.

This feature allows a UE to be paged in the UMTS LTE system for an incoming call in a legacy system (e.g., GSM system), and then be redirected to the legacy RAT (Radio Access Technology, e.g., GSM). This means that the UE can safely camp on or connect to a UMTS LTE cell without missing any incoming calls.

Typically, a UE learns whether CSFB is supported in a UMTS LTE cell when performing a combined registration for CS (Circuit Switched) and PS (Packet Switched) services. If CSFB is not supported, the registration will fail. The standard-compliant UE action when CS is not supported is to deactivate support for UMTS LTE.

If CSFB is not supported, gaps may occur in the use of the radio transceiver by the first radio access control unit (e.g., UMTS LTE) if the second radio access control unit (e.g., GSM) needs to listen for pages that allow UMTS LTE to camp or connect while (concurrently) camping on the legacy RAT (e.g., GSM) to monitor for CS pages.

Single Radio LTE (SR-LTE)

In SR-LTE, a single radio transceiver is shared between UMTS LTE and a legacy RAT (e.g., GSM) in a time-division manner. While the UE is camping on the legacy RAT (at the same time), it is connected to or camping on UMTS LTE. For example, when monitoring paging in the legacy RAT, reading system information, performing mobility measurements, making a location area update, or receiving a call related to the legacy RAT, the radio transceiver switches to the legacy RAT and any UMTS LTE activity may be punctured. Devices supporting SR-LTE do not rely on CSFB to be allowed to camp on or connect to UMTS LTE. SR-LTE can be considered a special case of DSDS (Dual SIM Dual Standby) where both SIMs are from the same operator (physically a single SIM).

If the second radio access control unit (legacy RAT, eg GSM) needs to perform any of the tasks exemplified above, gaps may occur in the usage of the radio transceiver by the first radio access control unit (eg UMTS LTE).

Use available additional receivers to monitor legacy RATs

A UE capable of carrier aggregation can use the available receivers additionally reserved for the secondary component carriers in the carrier aggregation to monitor paging in the legacy RAT, perform mobility measurements, and/or read system information. As long as there is sufficient separation between the UMTS LTE uplink (UL) and the legacy RAT downlink (DL) spectrum, it can simultaneously receive both the legacy RAT and UMTS LTE transmissions on the UL. Therefore, in this case, the legacy RAT can be monitored without any impact on UMTS LTE performance.

Typically, problems related to gaps in the usage of the radio transceiver by the first radio control unit (formed by the second radio access control unit) do not arise in this case.

If the spectrum separation between the UMTS LTE UL and the legacy RAT DL is insufficient, it is necessary to avoid conflicts between UMTS LTE UL transmissions and legacy RAT receptions to prevent high energy from leaking from the transmitter to the receiver and corrupting the received signal or even damaging the LNA (low noise amplifier) used in the radio transceiver. In many cases, this will mean skipping UMTS LTE UL transmissions when there is conflict with legacy RAT activity.

This situation may lead to problems arising in relation to gaps in usage of the radio transceiver by the first radio access control unit.

Dual SIM dual standby or active

In DSDS (Dual SIM Dual Standby) and DSDA (Dual SIM Dual Active), the UE is equipped with two SIM cards and simultaneously maintains (possibly) connectivity to two different networks (usually for different operators).

For DSDA, the UE is required to use a separate radio transceiver for each connection because, for example, it may use PS services for two SIM identities simultaneously, or PS services for one SIM and CS services for the other. When one of the connections is terminated, but the other connection is still active, the UE will be in idle mode for the SIM identity associated with the terminated connection. While in idle mode, it will monitor for paging and perform mobility management. For energy conservation reasons, it may be attractive to use only one of the receivers in a time-division manner to maintain connectivity to the first network and monitor for paging in the second network (or for a second identity in the same network).

Therefore, gaps may occur in the usage of the radio transceiver by the first (actively connected) radio access control unit when the second (idle mode) radio access control unit needs to monitor paging or perform mobility management.

For DSDS, it is not necessary to use two radio transceivers, as it is assumed that the UE will only be active for (at most) one network (or for one SIM identity) at any time, and will only monitor paging and perform mobility management in the other network. With this type of solution, DSDS is essentially similar to SR-LTE, in that the radio transceivers are used in a time-division manner, puncturing the ongoing connection, when reading pages from the other network.

Therefore, if the second radio access control unit (in idle mode) needs to perform any of the tasks exemplified above, gaps may occur in the usage of the radio transceiver by the first radio access control unit (with an active connection).

US 2014/0003260 A1 discloses manipulation of modulation and coding scheme (MCS) assignments after a communication interruption. First channel quality information may be generated and transmitted to a base station. A first MCS assignment based at least in part on the first channel quality information may be received from the base station. Second channel quality information may be generated and transmitted to the base station, wherein the second channel quality information is modified by an offset configured to modify the second MCS assignment.

This solution has an inherent delay before the appropriate MCS is applied after a communication interruption. Therefore, a throughput loss is experienced during the delay. In addition, the offset calculation is performed each time the method is applied, which is not very resource-efficient.

Therefore, a need exists for an alternative, improved way of handling gaps in usage of a radio transceiver.

Summary of the Invention

It should be emphasized that the terms “comprises/comprising” when used in this specification are used to indicate the presence of stated features, integers, steps or components, but do not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

It is an aim of some embodiments to alleviate at least some of the above disadvantages and to provide an alternative, improved way of handling gaps in usage of a radio transceiver.

According to a first aspect, this is achieved by a method of a wireless communication device comprising a radio transceiver and a first radio access control unit adapted to control operation of the wireless communication device in association with a first network node of a first cellular communication network.

The method comprises indicating (during use of a radio transceiver by a first radio access control unit) to a first network node a worse than actual channel condition, monitoring a code rate change of a signal transmitted from the first network node in response to the indication of the worse than actual channel condition, determining a relationship between the indication of the worse than actual channel condition and the code rate change, and determining an offset value based on the determined relationship.

The offset value may be applicable to offset a channel condition indication value to be transmitted to the first network node in association with a gap in usage of the radio transceiver by the first radio access control unit.

According to some embodiments, the wireless communication device may further include a second radio access control unit adapted to control operation of the wireless communication device in association with a second network node of a second cellular communication network. The second radio access control unit may be autonomous relative to the first radio access control unit, and the timing of the gap may be established (e.g., autonomously) by the second radio access control unit.

In some embodiments, indicating to the first network node that the channel condition is worse than actual may include at least one of the following:

- causing an increased error rate estimate of the first network node,

- sending a negative acknowledgement message to the first network node when an acknowledgement message would have been sent according to the actual channel conditions,

- transmitting to the first network node a channel condition indication value that is worse than the actual channel condition, and

- temporarily preventing use of the radio transceiver by the first radio access control unit.

In some embodiments, the method may further include storing the determined offset value in an offset value database.

In some embodiments, the method may further include receiving an offset determination request from a server external to the wireless communication device, wherein the offset determination request triggers an indication of a worse than actual channel condition to the first network node, and transmitting an offset value determination report to the server, wherein the offset value determination report causes the determined offset value to be stored in an offset value database included in the server.

According to some embodiments, the method may further comprise detecting an upcoming gap in usage of the radio transceiver by the first radio access control unit, and transmitting an offset channel condition indication value to the first network node in association with the upcoming gap. For example, the offset channel condition indication value may be transmitted just before the upcoming gap and/or just after the upcoming gap.

A second aspect is a computer program product comprising a computer readable medium having a computer program comprising program instructions thereon, the computer program being loadable into a data processing unit and adapted to cause the method according to the first aspect to be performed when the computer program is run by the data processing unit.

According to a third aspect, there is provided an arrangement for a wireless communication device comprising a radio transceiver and a first radio access control unit adapted to control operation of the wireless communication device in association with a first network node of a first cellular communication network.

The arrangement comprises a controller adapted to (during use of the radio transceiver by the first radio access control unit) cause an indication to the first network node of a worse than actual channel condition, monitor a code rate change of a signal transmitted from the first network node in response to the indication of the worse than actual channel condition, determine a relationship between the indication of the worse than actual channel condition and the code rate change, and determine an offset value based on the determined relationship.

The offset value may be applicable to offset a channel condition indication value to be transmitted to the first network node in association with a gap in usage of the radio transceiver by the first radio access control unit.

In some embodiments, the controller may include: a rate manipulator adapted to cause an indication of a worse than actual channel condition to the first network node; a rate monitor adapted to monitor a change in the rate of a signal transmitted from the first network node in response to the indication of the worse than actual channel condition; a relationship determiner adapted to determine a relationship between the indication of the worse than actual channel condition and the rate change; and an offset determiner adapted to determine an offset value based on the determined relationship.

According to some embodiments, the wireless communication device may further include a second radio access control unit adapted to control operation of the wireless communication device in association with a second network node of a second cellular communication network. The second radio access control unit may be autonomous relative to the first radio access control unit, and the timing of the gap may be established (e.g., autonomously) by the second radio access control unit.

According to some embodiments, the arrangement may further comprise means for storing the determined offset value in an offset value database.

In some embodiments, the arrangement may further comprise a detector adapted to detect an upcoming gap in usage of the radio transceiver by the first radio access control unit, a CQI calculator adapted to offset the channel condition indication value by the offset value, and a transmitter adapted to transmit the offset channel condition indication value to the first network node in association with the upcoming gap.

A fourth aspect is a wireless communication device comprising the arrangement according to the third aspect.

In some embodiments, the third and fourth aspects may additionally have features that are the same as or correspond to any of the various features explained above for the first aspect.

A fifth aspect is the use of a server comprising an offset value database for storing offset values applicable for offsetting a channel condition indication value to be transmitted by a wireless communication device to a network node of a cellular communication network in association with a gap in usage of a radio transceiver of the radio communication device by a radio access control unit of the wireless communication device, the radio access control unit being adapted to control operation of the wireless communication device in association with the network node.

In some embodiments, use may also include transmitting (by the transceiver of the server) an offset determination request to the wireless communication device, receiving (by the transceiver) a corresponding offset value determination report from the wireless communication device, and storing the offset value of the offset value determination report in an offset value database.

An advantage of some embodiments is that the throughput (of the system as a whole and/or of the wireless communication device) may be increased. In other words, the throughput loss due to gaps in the use of the radio transceiver may be reduced.

Another advantage of some embodiments is that by storing determined offset values for future use (by the wireless communication device and/or by other wireless communication devices), a resource efficient process is provided.

Yet another advantage of some embodiments is that by statistically combining the results of several offset determinations (possibly from several wireless communication devices), an accurate offset determination may be achieved.

Another advantage of some embodiments is that the offset value is determined based on the actual behavior of the network (e.g., MCS backoff). Therefore, there is little or no risk of using an offset that produces a channel quality indication corresponding to better channel conditions than are actually present.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects, features and advantages will appear from the following detailed description of embodiments with reference to the accompanying drawings, in which:

FIG1 is a schematic diagram illustrating transmit and/or receive gaps according to some examples;

FIG2 is a diagram illustrating HARQ transmissions and corresponding ACK/NACK transmissions according to some examples;

FIG3 is a diagram illustrating network modification of MCS and CQI adaptation during transmit and receive gaps according to some embodiments;

FIG4 is a flow chart illustrating example method steps according to some embodiments;

FIG5 is a flow chart illustrating example method steps according to some embodiments;

FIG6 is a flow chart illustrating example method steps according to some embodiments;

FIG7 is a block diagram illustrating an example arrangement according to some embodiments;

FIG8 is a block diagram illustrating an example arrangement according to some embodiments;

FIG9 is a block diagram illustrating an example arrangement according to some embodiments; and

FIG10 is a schematic diagram illustrating an example computer program product arrangement according to some embodiments.

DETAILED DESCRIPTION

Embodiments will be described below in which a wireless communication device compensates for MCS backoffs applied by a network node due to transmit and/or receive gaps autonomously created by the wireless communication device, thereby avoiding (or at least minimizing) throughput loss due to the gaps. The compensation performed by the wireless communication device includes applying an offset value to a channel condition indicator (e.g., CQI or CSI), where the offset value is determined relative to the applied MCS backoff. Some embodiments involve determining the offset value by the wireless communication device.

Without being considered limiting, a UE will be used as an example of a wireless communication device, and a CQI will be used as an example of a channel quality indication in many examples herein.

In some typical embodiments, the UE tracks the impact of autonomous gaps on the code rate (network backoff) and how long the impact lasts, and tunes CQI reporting accordingly to compensate for the impact and avoid or minimize throughput loss due to the gaps.

This can be achieved by the UE monitoring the code rate used by the network node before and after the autonomous gap and detecting whether a backoff occurs, the amount of the backoff, and how long the backoff lasts. Once the backoff is established, the UE can compensate for the backoff for more robust coding in conjunction with the next (or any subsequent) gap formed autonomously by the UE. Compensation typically involves boosting one or more CQI reports during the time interval after the autonomous gap and/or boosting one or more CQI reports sent just before the autonomous gap. The term boosting will be understood herein as applying an offset value.

Different backoff algorithms may be used throughout a network (eg, in different geographic regions and/or by different network providers), and some embodiments may be particularly useful for specific situations.

FIG3 shows an example of autonomously formed transmit and receive gaps (Tx blanking and Rx puncturing) 310 in a use 300 of a radio transceiver (compared to the UMTS LTE TDD of FIG1 ). Part a) shows the operation of a network node and a wireless communication device without applying any embodiments, and part b) shows how some embodiments can be applied to reduce throughput loss due to the gaps.

Before the gap, the wireless communication device experiences a constant channel quality level, and the reported CQI (CQI on the UE side) 321, 331 is correspondingly constant. The downlink block error rate (DLBLER on the eNB side) 320, 330 as estimated at the network node is also constant before the gap, and accordingly, the MCS (DL code rate) 322, 332 used for downlink transmissions remains constant.

During the autonomous gaps, the network node will experience an increase in the downlink block error rate as shown by the slope of line 320 between times 324 and 325 and by the slope of line 330 between times 334 and 335 (e.g., due to the absence of ACK/NACKs, or any other reason resulting from the formation of the gaps).

Experiencing an increase in the downlink block error rate during a gap typically causes the network node to back off in code rate and/or modulation and fall back to a more robust MCS. This is shown as the line for DL code rate 322 in part a) of FIG3 starts at a low level after communications are resumed after the gap at time 325.

In the example of Figure 3, the channel quality level experienced by the wireless communication device is the same before and after the gap, as shown by the same reported CQI (UE-side CQI) 321 before and after the gap in part a) of Figure 3. When communication resumes after the gap at time 325 and the network node begins receiving CQI reports (and other communications from the wireless communication device), as shown by the slopes of lines 320 and 322 during the back-off time 323 in part a) of Figure 3, by gradually modifying the MCS, the network node will eventually converge to the same downlink BLER as experienced before the gap.

The increased robustness of the MCS and the delay due to convergence lead to a loss of throughput as already described in detail above. Part b) of Figure 3 shows a solution to mitigate this throughput loss.

In this example, even though the channel quality level experienced by the wireless communication device is the same before and after the gap, the reported CQI is increased by offset 336 immediately after communication resumes after the gap at time 335. As shown in part b) of Figure 3 at the starting point of the line for DL code rate 332 at time 335 after communication resumes after the gap, this increase causes the network node to use a less robust MCS than in part a) upon receiving the increased CQI. The difference 337 between the starting points of lines 322 and 332 after the gap illustrates the improvement in code rate, i.e., the difference in robustness, from line 322 to line 332. Thus, after communication resumes after the gap at time 335, DL code rate 332 starts at a higher (less robust) level than the corresponding line 322 in part a), and the throughput loss is (at least partially) mitigated.

Block errors occur due to the gaps and increase the short-term DL BLER (which can typically be evaluated over the last 200 ms). Since the gap lengths are the same, the number of such errors is the same for parts a) and b) of Figure 3. Therefore, in this example, the downlink block error rate, as estimated by network nodes 320, 330, is the same in parts a) and b).

FIG4 illustrates an example of a method according to some embodiments. The method may be performed, for example, by a wireless communication device comprising a radio transceiver and a radio access control unit adapted to control operation of the wireless communication device in association with a network node of a cellular communication network. As shown in step 400, the method may begin during use of the radio transceiver by the radio access control unit in accordance with a radio access technology (RAT 1) employed by the cellular communication network.

As described in detail above, gaps in usage of the radio transceiver by the first radio access control unit may be established autonomously by, for example, a second radio access control unit included in the wireless communication device. The second radio access control unit may be adapted to control operation of the wireless communication device associated with a second network node of a second cellular communication network and may be autonomous relative to the first radio access control unit. The second cellular communication network may utilize the same or a different radio access technology as the cellular communication network associated with the first radio access control unit.

In step 410, the wireless communication device indicates to a network node that the channel condition is worse than the actual condition.

In the example of FIG4 , this is achieved by causing an increased block error rate estimate (BLER _est ) for the network node. For example, the increased block error rate estimate may be caused by transmitting a NACK to the network node when an ACK would otherwise be transmitted based on actual channel conditions (e.g., when a HARQ transport block has been correctly received) to simulate a gap in the use of the radio transceiver by the radio access control unit. Alternatively, or in addition, the increased block error rate estimate may be caused by temporarily preventing the radio transceiver from being used by the radio access control unit (i.e., creating an actual gap).

Alternatively or additionally, the wireless communication device may indicate to the network node that the channel condition is worse than it actually is by transmitting a channel condition indication value (eg, a lower CQI) that is worse than it actually is.

Subsequently, in step 420, the wireless communication device monitors a change in the code rate of the signal transmitted from the network node in response to the indication of worse-than-actual channel conditions from step 410. The change is typically a reduction in the code rate (e.g., a more robust MCS), and the amount and/or duration of the reduction (compared to 323 of FIG. 3 ) may be monitored. References to code rate herein may be understood to include one or more of coding rate, modulation format, MCS, and amount of allocated resources. In addition to, or as an alternative to, using a more robust MCS in response to the assumed worse channel conditions, the network node may, for example, allocate fewer resources to the wireless communication device in response to the assumed worse channel conditions.

In step 430, the wireless communication device determines the relationship between worse channel conditions (eg, BLER _est ) than indicated in step 410 and the corresponding change in code rate. Thus, the backoff algorithm applied by the network is essentially (at least partially) determined.

Based on the relationship determined in step 430, an offset value is determined in step 440, wherein the offset value may be applicable to offset a channel condition indicator value (e.g., CQI or CSI) to be transmitted to the network node in association with a gap in usage of the radio transceiver by the radio access control unit. A time window may also be determined during which the offset value is to be applied (possibly decreasing toward zero).

Once determined, the offset value (and possibly the time window) may be stored in an offset value database in step 450. The offset value database may be included, for example, in the wireless communication device itself, in a network node, or in a cloud-based server. In some embodiments, the offset value database may have different entries for different geographic areas (e.g., tracking areas or location areas). Different entries may also exist depending on the length of the gap and/or the channel condition indicator value corresponding to the actual channel condition.

When the offset value database is included in a server external to the wireless communication device, the method of Figure 4 (i.e., execution of step 410) may be triggered by receiving an offset determination request from the server, and step 450 may include transmitting an offset value determination report to the server, which causes the determined offset value to be stored in the offset value database.

By applying this variation of the method, the server can request offset value determinations from a plurality of selected wireless communication devices according to the method of FIG. 4 . The results can be used as a statistical basis for offset values of database entries. Thus, according to some embodiments, offset value determinations do not necessarily need to be performed by all wireless communication devices.

Figure 5 illustrates an example of a method according to some embodiments. The method may be performed, for example, by a wireless communication device comprising a radio transceiver and a radio access control unit adapted to control the operation of the wireless communication device in association with a network node of a cellular communication network. This wireless communication device may be the same as or different from the wireless communication device of Figure 4 . In Figure 5 , it is assumed that a gap in the use of a radio transceiver by a first radio access control unit (associated with a first radio access technology, RAT 1) is autonomously established by a second radio access control unit (associated with a second radio access technology, RAT 2) included in the wireless communication device. The gap is illustrated in step 540 and corresponds to the time when RAT 2 is in use, and the end of the gap is indicated by step 550 when RAT 1 is resumed.

It should be noted that other scenarios of gap establishment (eg by negotiation between the first and second radio access control units) may be applicable according to various embodiments.

As shown in step 500 , the method may begin during use of a radio transceiver by a first radio access control unit.

In step 510, an impending gap in usage of a radio transceiver by a first radio access control unit is detected, and in step 520, a stored offset value applicable to a channel condition indication (e.g., CQI or CSI) associated with the gap is read from an offset value database. The offset value database may, for example, be included in the wireless communication device itself, in a network node, or in a cloud-based server.

As shown in step 530, the offset value may be applied to the channel condition indication transmitted just before the upcoming gap. Alternatively or additionally, as shown in step 560, the offset value may be applied to the channel condition indication transmitted just after the upcoming gap. Alternatively or additionally, the offset value (which may be continuously decreasing) may be applied to several channel condition indications transmitted after the upcoming gap, e.g., during a backoff period associated with the offset value.

In general, it should be noted that the offset value can be static (single value) or dynamically adjustable.

FIG6 illustrates an example of a method according to some embodiments. This method is particularly suitable when the offset determination is made "on the fly" during an actual transmit/receive gap, and the offset determined (or adjusted) during one gap can be applied to subsequent gaps. The method can be performed, for example, by a UE operating in conjunction with a UMTS LTE network.

The method starts in step 600 where the UE tracks the code rate (eg, MCS) of the PDSCH (Physical Downlink Shared Channel) used for transmissions associated with the C-RNTI (Cell Radio Network Temporary Identity) of the cell with which it is currently associated.

When an autonomous gap occurs, in step 610, the UE compares the rate robustness before and after the gap.

If the code rate robustness does not increase during the gap (the "No" path out of step 620), then as shown at 660 in FIG6 , the UE may conclude that there are no issues with fallback in this location and for this network, or that any issues have been mitigated (e.g., by having applied a CQI offset determined at an earlier point in time and/or by one or more other suitable methods). The determination at 660 may be made immediately or after performing steps 600-620 for several gaps.

If the code rate robustness has increased during the gap ("yes" path out of step 620), and if the mitigation (CQI offset and/or one or more other suitable methods) has been correctly applied ("yes" path out of step 630), then the UE may conclude that the problem still exists, as shown at 670 in Figure 6. If so, the UE may additionally try to use other means to try to mitigate the backoff (e.g., avoiding forming autonomous gaps when CQI reports are to be sent to the network and/or when sounding reference signals are to be transmitted) and/or may apply autonomous gaps less frequently (e.g., to limit any impact on the PDCCH BLER, which typically has a more stringent BLER target than the PDSCH).

For example, autonomous gaps may be avoided in certain time windows by using priorities associated with requests to use a radio transceiver (where, for example, the highest priority request starts the radio transceiver, and CQI report registration has a higher priority than other radio activities), and/or by not monitoring some paging occasions (e.g., every second paging occasion).

If the code rate robustness has increased during the gap ("yes" path out of step 620), and if mitigation (CQI offset and/or one or more other suitable methods) has not been applied - at least not with an appropriate offset value, e.g. determined according to the latest offset value - ("no" path out of step 630), then in step 640 the UE estimates the duration of the backoff (e.g., MCS reduction) after the gap (compare to 323 of Figure 3), and in step 650 configures the CQI boost mitigation method to be applied during (at least part of) the estimated duration.

The various steps of the methods described in conjunction with Figures 4, 5 and 6 may be combined in any suitable manner.

Figure 7 shows an arrangement for a wireless communication device. The arrangement may be adapted to perform any of the methods described in conjunction with Figures 4, 5 and 6, for example.

The wireless communication device comprising the arrangement has a radio transceiver, shown in FIG7 as a receiver (RX) 780 and a transmitter (TX) 770, and at least a first radio access control unit adapted to control operation of the wireless communication device in association with a first network node of a first cellular communication network.

The arrangement comprises a controller 700, which may be included in a first radio access control unit. The controller 700 is adapted to, during use of the radio transceiver by the first radio access control unit, cause an indication of a worse-than-actual channel condition to be given to the first network node (e.g., by a rate manipulator 705, compare with step 410 of FIG. 4 ), monitor a rate change of a signal transmitted from the first network node in response to the indication of the worse-than-actual channel condition (e.g., by a rate monitor 710, compare with step 420 of FIG. 4 ), determine a relationship between the indication of the worse-than-actual channel condition and the rate change (e.g., by a relationship determiner 720, compare with step 430 of FIG. 4 ), and determine an offset value based on the determined relationship (e.g., by an offset determiner 730, compare with step 440 of FIG. 4 ).

The offset value may be suitable for offsetting a channel condition indication value to be transmitted to the first network node in association with a gap in usage of the radio transceiver by the first radio access control unit. To this end, the controller 700 may further include a gap detector 740 adapted to detect an upcoming gap in usage of the radio transceiver by the first radio access control unit (compare to step 510 of FIG. 5 ) and a CQI calculator 750 adapted to offset the channel condition indication value by the offset value (compare to steps 530 and 560 of FIG. 5 ) before transmitting the offset channel condition indication value to the first network node in association with the upcoming gap.

In some embodiments, the arrangement also comprises means for storing the determined offset values (compared with step 450 of FIG. 4 ) in an offset value database (DB) 760. The offset value database 760 may be comprised in the wireless communication device (and may even be comprised in the arrangement), or it may be located, for example, in a network node or a cloud-based server.

In embodiments where the determined offset value is stored in an offset value database, the gap detector 740 may be adapted to cause the stored offset value to be read (compare to step 540 of FIG. 5 ), which is then used by the CQI calculator 750 .

The offset value database may have different entries, eg, for different geographical locations, different network providers, different (not yet offset) CQI values, and/or different gap lengths.

Storing the determined offset value in the offset value database may include storing the actual determined offset value, or using the determined offset value as part of a statistical basis for determining the offset value for an entry of the database.

The entry may for example be determined as a (weighted) average of several determined offset values (possibly from different wireless communication devices).Alternatively or additionally, the entry may for example be determined by filtering several determined offset values (possibly from different wireless communication devices).

Entries of the offset value database may be time stamped, and older values may be considered less reliable than newer values.

A server including an offset value database may be adapted to transmit offset determination requests to one or more wireless communication devices and receive corresponding offset value determination reports from the wireless communication devices for storage in the offset value database. This allows the server to sort offset value determinations from the one or more wireless communication devices as appropriate (e.g., when entries include less reliable values).

Therefore, it is not necessary for all wireless communication devices to perform offset value determination, which improves overall efficiency.

8 schematically illustrates the architecture of a wireless communication device, where some embodiments may be applicable. The architecture includes a radio transceiver (RX/TX) 800 shared between a first radio access control unit (RAT 1) 810 and a second radio access control unit (RAT 2) 830. A radio transceiver control unit (CNTR) 820 may be adapted to control the sharing of the radio transceiver 800.

As described in detail above, gaps in usage of the radio transceiver 800 by the first radio access control unit 810 may be established autonomously by the second radio access control unit 830, and the first radio access control unit 810 may apply embodiments as appropriate to mitigate the adverse effects of the gaps.

Figure 9 schematically illustrates an arrangement of a wireless communication device according to some embodiments and will be described in terms of UMTS LTE. As shown at 940, a downlink control information (DCI) decoder 900 and a CQI estimator 910 receive signals from the Rx chain.

DCI decoder 900 decodes downlink control information (eg, MCS information) carried on the PDCCH of signal 940. CQI estimator 910 estimates channel quality on OFDM symbols where the PDCCH is transmitted in the control region and accordingly determines a CQI based on the actual channel quality.

The DCI decoder 900 and CQI estimator 910 communicate their findings to a processing unit 920, which calculates the code rate for the transport block associated with the C-RNTI based on the MCS and allocation provided in the DCI. The processing unit 920 also tracks when autonomous gaps occur. The processing unit 920 provides the estimated CQI and any possible boost (offset value) to be applied in conjunction with the gaps to a CQI reporter 930, which prepares the CQI report for transmission on the uplink and, as shown at 950, transmits the CQI report to the transmit (Tx) chain.

In some embodiments, processing unit 920 may also monitor the CQI estimates provided by CQI estimator 910 over time to detect whether channel conditions have changed, and adjust its instructions to the CQI reporter accordingly.

Other inputs (not shown) to the processing unit 920 may include, for example, the calculated BLER for the transport block associated with the C-RNTI.

One or more blocks of FIG. 9 may be included in the controller 700 described in conjunction with FIG. 7 .

Several illustrative examples will now be given to further illustrate operation in accordance with various embodiments.

The UE monitors the DCI to assess whether a fallback occurs

The UE monitors the code rate used for transport blocks received on the PDSCH suitable for the C-RNTI (Cell Radio Network Temporary Identity) and compares the code rate used before the autonomous gap with the code rate used after the autonomous gap to detect whether the eNodeB has applied a backoff (e.g. due to the assumption that the UE experiences worse radio propagation conditions).

The code rate information can be retrieved from the DCI on the PDCCH following the procedures in 3GPP TS 36.213 v10.12.0, section 7.1.7. Specifically, the modulation block size index, ITBS, is determined using the transmitted parameter IMCS. This is further used to look up the transport block size in a lookup table that depends on the allocation size and the number of mapped layers (e.g., see Tables 7.1.7.2.1-1, 7.1.7.2.2-1, 7.1.7.2.4-1, and 7.1.7.2.5-1 of 3GPP TS 36.213 v10.12.0). The total number of transmitted bits can be calculated by considering all resource elements in the allocated bandwidth that are not reserved for reference signals, synchronization signals, or physical broadcast channels, and taking into account the modulation order (2 bits per resource element for QPSK, 4 bits for 16QAM, and 6 bits for 64QAM). The modulation index, Qm _, is given by the transmitted IMCS. The code rate can be derived by the UE as the transport block size divided by the total number of bits transmitted. The actual allocation to the UE may vary in different subframes. Therefore, the code rate may fluctuate slightly across received transport blocks. To suppress fluctuations, the code rate of the most recently received transport blocks can be filtered, for example, using a median filter over a sliding window of, for example, more than 20 transport blocks.

Therefore, the UE may compare the filtered code rates before and after the autonomous gap to detect whether the transmission after the autonomous gap is more robust (lower code rate and/or lower ITBS) than just before the gap.

An alternative to calculating the code rate as explained above is to use the combination of ITBS and _Qm directly as an approximation of the code rate, thereby reducing the need to use a lookup table and calculate the total number of bits.

If the UE determines that there is a substantial change in code rate after the gap as compared to before the gap (e.g., a decrease of 10% or more), the UE may consider that the autonomous gap has been backed off by the eNB. The threshold used to compare the code rate difference within the determination may be a static threshold, or may be a variable threshold that depends, for example, on the modulation and coding scheme used just before the autonomous gap.

According to some embodiments, the UE continues to monitor the code rate for a certain duration (eg, 200ms) after the autonomous gap to determine (at least approximately) the number of subframes it used before the backoff has been removed (ie, the control loop has converged).

The UE may repeat the above detection multiple times (eg, over multiple autonomous gaps) to improve detection performance.

The UE monitors the DL BLER to assess whether a fallback occurs.

The UE monitors the block error rate of transport blocks received on the PDSCH for the appropriate C-RNTI and estimates the BLER before and after the autonomous gap. If the BLER decreases immediately after the gap, the UE may assume that the autonomous gap has been backed off by the eNB.

If the autonomous gap is partial (e.g., Tx-only blanking), the UE can still receive when scheduled during the gap, although it cannot send ACK/NACK or otherwise transmit on the uplink. Therefore, in such a scenario, the UE knows whether it is scheduled and can calculate the DL BLER seen by the eNB even during the gap (where the BLER depends on the combined effect of the radio conditions and the autonomous gap).

UE tunes CQI reporting to compensate for fallback

A UE that has detected that autonomous gaps lead to a backoff (and how long the backoff period is) can increase CQI reporting to compensate (at least partially) for the throughput loss that occurs when the eNB sends data that is more robustly coded than required by the radio propagation conditions.

The boost can be fixed (e.g., increasing the CQI index by one step) or variable (e.g., depending on how much code rate loss has been detected). When applying a variable boost, a lookup table can be used to find which offset value (boost) should be applied. The lookup table can, for example, have one column per code rate before the gap, one row per code rate after the gap (i.e., after backoff), and an element that indicates the amount by which the reported CQI should be boosted (offset). Alternatively, or in addition, the variable boost can be expressed by a mathematical function.

Boosting may be applied for CQI reporting opportunities that occur immediately after an autonomous gap. Alternatively, or in addition, boosting may already be applied for CQI reporting opportunities that occur immediately before an autonomous gap (e.g., if such opportunities fall within 10 subframes before the autonomous gap). In some embodiments, boosting may continue until the last CQI reporting opportunity falls within the duration (time period) for which fallback has been detected. Boosting may also be stopped earlier if it is determined that the achieved code rate has reached the code rate used immediately before the gap.

UE dynamically tunes CQI reporting to compensate for fallback

In addition to using the above principles, the UE evaluates how the code rate differs from the code rate just before the gap in each CQI reporting opportunity within the detection duration for fallback, and gradually reduces the boost until it is fully reduced or until the duration has ended. The UE can reduce the original boost by gradually decreasing the initial boost, or it can reduce the original boost by using the lookup table detailed above to obtain a new appropriate boost value before each CQI reporting opportunity.

UE monitors CQI to track channel condition changes

In addition to using the principles described above, the UE tracks the derived CQI (excluding boosting) to detect changes in channel conditions. The UE evaluates whether the CQI is fluctuating and, if so, estimates the hypothetical impact of the fluctuation on the code rate. The UE then uses this evaluation to modify the target code rate for boosting. Therefore, according to this example, if channel conditions change, the code rate immediately before the autonomous gap is no longer considered a static target. Instead, the code rate immediately before the autonomous gap is used as a starting point, and the code rate target is modified depending on the changing channel conditions.

UE stores and/or shares information about fallback and mitigation solutions

In addition to using the above principles, the UE may store information about the determination of the detected backoff (e.g., whether the backoff was applied, how big it was and/or its duration after the gap) locally as historical information, or share it with a node in the network and/or with a server in the cloud. If the information is stored in a network node or server, it can be retrieved later by the UE or another UE (e.g., upon entering an applicable tracking area). The stored information may include, for example, one or more of the following parameters:

- PLMN (Public Land Mobile Network)

- Tracking area

- Carrier frequency

- Physical cell identity

- Whether to apply fallback

Mitigation options (e.g., whether methods according to some embodiments have been successfully applied, whether other methods have been successfully applied, whether no successful mitigation has been found)

Determine the offset value based on the code rate response indicated by the worse channel condition than the actual channel condition

In this example, the UE measures the CQI and finds that the estimated CQI fluctuates within a specific range (e.g., CQI 11 to 13) under stable DL BLER and UL BLER as observed from the UE side, the code rate is in the range of 0.55 to 0.75 according to the following table (this corresponds to a portion of the table disclosed above, in which the code rate is expressed as a decimal fraction).

CQI index MCS Bitrate … … … 10 19 0.46 11 twenty one 0.55 12 twenty three 0.65 13 26 0.75 14 27 0.85 15 28 0.92

When the BLER increases due to an indication of worse channel conditions than actually occurring (e.g., in the form of intentional NACKs sent after successfully decoding multiple consecutive (or otherwise temporally close to each other) transport blocks, or in the form of actual autonomous gaps of a certain length), the UE may find that the CQI is still in the range of CQI 11 to 13, but the code rate has been reduced (e.g., by approximately 0.1, so in the range of 0.46 to 0.65).

Based on the number of induced block errors that exceed the block errors due to radio propagation, the UE can determine that for a particular gap length, the backoff in the base station due to link adaptation will correspond to a 0.1 reduction in code rate (equivalent to one CQI level within this particular CQI range). Therefore, when measuring CQI 11 (which corresponds to 0.46 in code rate due to link adaptation), the UE can apply a boost corresponding to one CQI level and send CQI 12 (which may result in the UE obtaining a code rate of 0.55 relative to the measured CQI 11).

Therefore, when the UE introduces autonomous gaps, it will be able to understand what impact they have on link adaptation and will be able to compensate by boosting the CQI before reporting.

In various embodiments, the boost can be a function of the residual between the previously identified code rate without additional error blocks and the code rate of the short-term filter. The boost can, for example, be gradually reduced and stopped when the residual is less than a certain threshold, or a certain maximum time has passed (whichever comes first).

The described embodiments and their equivalents may be implemented in software or hardware, or a combination thereof. They may be implemented by general-purpose circuitry associated with or as part of a communication device, such as a digital signal processor (DSP), a central processing unit (CPU), a coprocessor unit, a field programmable gate array (FPGA), or other programmable hardware, or by specialized circuitry, such as an application-specific integrated circuit (ASIC). All such forms are contemplated to be within the scope of the present disclosure.

The embodiments may be implemented in an electronic device (e.g., a wireless communication device) that includes circuitry/logic or performs a method according to any of the embodiments. The electronic device may be, for example, a user device, a portable or handheld mobile radio communication device, a mobile radio terminal, a mobile phone, a communicator, an electronic organizer, a smartphone, a computer, a notebook computer, or a mobile gaming device.

According to some embodiments, the computer program product includes a computer-readable medium such as, for example, a disk, a USB stick, a plug-in card, an embedded drive, or a CD-ROM as shown at 1000 in FIG. 10 . The computer-readable medium 1000 may have a computer program including program instructions stored thereon. The computer program may be loaded into a data processing unit (PROC) 1020, which may be included, for example, in the wireless communication device 1010. When loaded into the data processing unit 1020, the computer program may be stored in a memory (MEM) 1030 associated with or part of the data processing unit 1020. According to some embodiments, the computer program, when loaded into and executed by the data processing unit, may cause the data processing unit to perform method steps according to, for example, any of the methods shown in any of FIG. 4 , 5 , and 6 .

Reference is made herein to various embodiments. However, those skilled in the art will recognize many variations of the described embodiments that would still fall within the scope of the claims. For example, the method embodiments described herein describe example methods with method steps performed in a certain order. However, it is recognized that these sequences of events can occur in another order without departing from the scope of the claims. Furthermore, some method steps, even if described as being performed sequentially, may be performed in parallel.

Likewise, it should be noted that, in the description of the embodiments, the division of functional blocks into specific units is not intended to be limiting. On the contrary, these divisions are merely examples. A functional block described herein as a single unit may be divided into two or more units. Likewise, a functional block described herein as implemented as two or more units may be implemented as a single unit without departing from the scope of the claims.

Therefore, it should be understood that the details of the described embodiments are for illustrative purposes only and are not intended to be limiting. On the contrary, all changes that fall within the scope of the claims are intended to be embraced therein.

Claims (15)

1. A method for a wireless communication device including a radio transceiver and a first radio access control unit, the first radio access control unit being adapted to control the operation of the wireless communication device associated with a first network node of a first cellular communication network, the method comprising, during use of the radio transceiver by the first radio access control unit: Indicate (410) to the first network node that the channel conditions are worse than they actually are; In response to the indication of channel conditions that are worse than actually, the code rate change of the signal transmitted from the first network node is monitored (420); Determine the relationship between the worse-than-actual channel condition indication and the code rate change (430); and Based on the established relationship, an offset value (440) is determined, wherein the offset value is applicable to offsetting the channel condition indication value to be transmitted to the first network node in association with the gap in the use of the radio transceiver by the first radio access control unit. 2. The method of claim 1, wherein the wireless communication device further comprises a second radio access control unit adapted to control the operation of the wireless communication device associated with a second network node of a second cellular communication network, the second radio access control unit being autonomous relative to the first radio access control unit, and wherein the timing of the gap is set by the second radio access control unit. 3. The method of claim 1 or 2, wherein instructing the first network node to indicate the worse-than-actual channel conditions comprises at least one of the following: This causes an increase in the error rate estimation of the first network node; When transmitting an acknowledgment message based on actual channel conditions, a negative acknowledgment message is transmitted to the first network node. Transmit a channel condition indication value that is worse than the actual value to the first network node; and Temporarily prevent the first radio access control unit from using the radio transceiver. 4. The method of claim 1 or 2, further comprising storing (450) determined offset values in an offset value database. 5. The method as described in any one of claims 1 or 2, further comprising: Receive an offset determination request from a server outside the wireless communication device, wherein the offset determination request triggers a worse-than-actual channel condition indication to the first network node; and An offset value determination report is transmitted to the server, wherein the offset value determination report causes the determined offset value to be stored in an offset value database included in the server. 6. The method of claim 1 or 2, further comprising: Detection (510) of impending gaps during the use of the radio transceiver by the first radio access control unit; and The channel condition indication value of the offset (530, 560) is transmitted to the first network node in association with the impending gap. 7. The method of claim 6, wherein the channel condition indication value of the offset is transmitted (530) just before the impending gap. 8. The method of claim 6, wherein the channel condition indication value of the offset is transmitted (560) exactly after the impending gap. 9. A computer-readable medium (1000) having a computer program thereon, the computer program including program instructions, the computer program being loadable into a data processing unit (1020) and adapted to cause the execution of the method as claimed in any one of claims 1 to 8 when the computer program is run by the data processing unit. 10. An apparatus for a wireless communication device including a radio transceiver and a first radio access control unit, the first radio access control unit being adapted to control the operation of the wireless communication device associated with a first network node of a first cellular communication network, the apparatus including a controller (700) adapted to perform the following operations during use of the radio transceiver by the first radio access control unit: This causes the first network node to indicate channel conditions that are worse than they actually are. In response to the indication of channel conditions that are worse than actually, the code rate change of the signal transmitted from the first network node is monitored; Determine the relationship between the worse-than-actual channel condition indication and the code rate change; and Based on the established relationship, an offset value is determined, wherein the offset value is applicable to the channel condition indication value to be transmitted to the first network node in association with the gap in the use of the radio transceiver by the first radio access control unit. 11. The device of claim 10, wherein the controller comprises: A rate manipulator (705) is adapted to induce a channel condition indication to the first network node that is worse than the actual condition. A code rate monitor (710) is adapted to monitor the code rate change of the signal transmitted from the first network node in response to the indication of channel conditions that are worse than actually. Relationship determiner (720), adapted to determine the relationship between the channel condition indication that is worse than actual and the code rate change; and An offset determiner (730) is adapted to determine the offset value based on a defined relationship. 12. The device of claim 10 or 11, wherein the wireless communication device further comprises a second radio access control unit adapted to control the operation of the wireless communication device associated with a second network node of a second cellular communication network, the second radio access control unit being autonomous relative to the first radio access control unit, and wherein the timing of the gap is set by the second radio access control unit. 13. The device of claim 10 or 11, further comprising a component for storing the determined offset values in an offset value database. 14. The device as claimed in any one of claims 10 or 11, further comprising: A detector (740) is adapted to detect impending gaps during the use of the radio transceiver by the first radio access control unit; CQI calculator (750), adapted to offset the channel condition indication value by the offset value; and Transmitter (770) is adapted to transmit an offset channel condition indication value to the first network node in association with the impending gap. 15. A wireless communication device including the apparatus of any one of claims 10 to 14.