CN106559830B

CN106559830B - Method and apparatus for measuring and reporting received signal strength indication in licensed assisted access

Info

Publication number: CN106559830B
Application number: CN201510623186.0A
Authority: CN
Inventors: 孟艳; 刘建国; 陶涛; 韩锋; 谷俊嵘; 沈钢
Original assignee: Alcatel Lucent SAS
Current assignee: Alcatel Lucent SAS
Priority date: 2015-09-25
Filing date: 2015-09-25
Publication date: 2020-07-07
Anticipated expiration: 2035-09-25
Also published as: CN106559830A

Abstract

Embodiments of the present disclosure provide methods and apparatus for measuring and reporting received signal strength indication, RSSI, in licensed assisted access, and methods and apparatus for using RSSI in licensed assisted access. The method for measuring and reporting RSSI in the licensed assisted access comprises: determining whether an indication of a channel occupancy state is received from a base station; measuring RSSI based on the determination; and reporting the measured RSSI to the base station. The RSSI measurement and reporting mechanism according to embodiments of the present disclosure can keep the signaling overhead low.

Description

Method and apparatus for measuring and reporting received signal strength indication in licensed assisted access

Technical Field

Embodiments of the present disclosure relate generally to wireless communication technology and, more particularly, relate to a method and apparatus for measuring and reporting a Received Signal Strength Indication (RSSI) in a Licensed Assisted Access (LAA) and a method and apparatus for using the RSSI in the LAA.

Background

The long term evolution, LTE, of the third generation partnership project, 3GPP, which is conventionally deployed in licensed spectrum is facing a tremendous increase in data traffic. Even though LTE is able to efficiently utilize spectrum, the spectrum licensed for LTE is very limited and is exclusively reserved. Therefore, LTE is being considered to be deployed in unlicensed spectrum below 6GHz, which will be LTE-LAA (hereinafter abbreviated LAA) deployed for unlicensed spectrum.

Technical report TR 36.889-101 with LAA specifies that reporting of a measurement of Received Signal Strength Indication (RSSI) to an evolved node b (eNB) by a User Equipment (UE) for the purpose of detecting hidden nodes in channel selection is considered useful and that the eNB can indicate for which carrier the UE should report RSSI.

LTE Radio Resource Management (RRM) measurements, which are essential for mobility and load balancing, mainly include measurements of Reference Signal Received Power (RSRP), Reference Signal Received Quality (RSRQ), and RSSI. Wherein RSRP represents the average value of the received signal power over all Resource Elements (REs) carrying reference signals within a particular symbol (symbol), i.e. the useful signal power; the RSSI represents the average value of the power of all signals (including reference signals and data signals, adjacent cell interference signals, noise signals, etc.) received in the specific symbol, i.e. the load of the frequency layer; RSRQ represents signal quality. On the licensed spectrum, legacy UEs perform RRM measurements based on continuously transmitted Common Reference Signals (CRS) and/or low duty cycle periodic discovery signals. Furthermore, although RSRP, RSRQ, and RSSI all need to be measured at the UE side, the UE only reports RSRP and RSRQ to the eNB.

For LAA, RRM measurements should at least maintain all legacy functions of LTE RRM measurements. Furthermore, as laaeenb must coexist with other Radio Access Technologies (RATs), LAA RRM measurements should support other functions for inter-RAT coexistence, such as Clear Channel Access (CCA) and carrier selection. Thus, not only the RSSI needs to be measured, but also the measured RSSI needs to be reported to the eNB so that the eNB knows the interference on the UE side and the loading condition of the carrier. In addition, the eNB may utilize statistics of RSSI in certain procedure periods for carrier selection. Further, RSSI reporting by the UE is also believed to help solve the hidden node problem.

Therefore, there is a need to introduce an efficient RSSI measurement and reporting mechanism, at least for the purpose of carrier selection and hidden node detection, while keeping the signaling overhead low. However, it is not known as yet how to design RSSI measurement and reporting mechanisms to support both purposes.

Disclosure of Invention

Embodiments of the present disclosure provide a method and apparatus for measuring and reporting RSSI in an LAA and a method and apparatus for using RSSI in an LAA to solve or at least partially alleviate the above-mentioned problems in the prior art.

According to a first aspect of embodiments of the present disclosure, a method for measuring and reporting RSSI in an LAA is provided. The method comprises the following steps: determining whether an indication of a channel occupancy state is received from a base station; measuring RSSI based on the determination; and reporting the measured RSSI to the base station.

In some embodiments, measuring RSSI based on the determination comprises: in response to determining that the indication of the channel occupancy state is not received, measuring a plurality of instantaneous RSSIs during a measurement period.

In some embodiments, the method further comprises: in response to determining that the indication of the channel occupancy state is not received, detecting a reference signal from a subframe from the base station; and in response to detecting the reference signal, determining that the channel occupancy status is a busy status.

In some embodiments, measuring RSSI based on the determination comprises: in response to determining that the indication of the channel occupancy state is received and that the indication of the channel occupancy state indicates that the channel occupancy state is a busy state, measuring a plurality of instantaneous RSSIs during a measurement period.

In some embodiments, reporting the measured RSSI to the base station comprises: calculating differences between the plurality of instantaneous RSSIs and respective Reference Signal Received Powers (RSRPs); comparing each of the differences to a first predetermined threshold; and in response to at least one of the difference values being greater than the first predetermined threshold, reporting the at least one difference value to the base station, or reporting an interference indication to the base station.

In some embodiments, the method further comprises: in response to determining that the indication of the channel occupancy state is not received, detecting a reference signal from a subframe from the base station; and in response to not detecting the reference signal, reporting the plurality of instantaneous RSSIs to the base station.

In some embodiments, measuring a plurality of instantaneous RSSIs during a measurement period in response to determining that the indication of the channel occupancy state is not received comprises: detecting a silent subcarrier pre-configured by the base station from a subframe from the base station; and in response to detecting the muted subcarriers, measuring the plurality of instantaneous RSSIs on the muted subcarriers.

In some embodiments, reporting the measured RSSI to the base station further comprises: reporting a measurement time associated with the instantaneous RSSI to the base station.

In some embodiments, measuring RSSI based on the determination comprises: measuring a plurality of instantaneous RSSIs during a measurement period in response to determining that the indication of the channel occupancy state is received and that the indication of the channel occupancy state indicates that the channel occupancy state is an idle state; and calculating an average of the plurality of instantaneous RSSIs.

In some embodiments, reporting the measured RSSI to the base station comprises: reporting the average of the plurality of instantaneous RSSIs to the base station.

In some embodiments, the method further comprises: comparing the plurality of instantaneous RSSIs to a second predetermined threshold; calculating a ratio between the number of instantaneous RSSIs greater than the second predetermined threshold and the number of instantaneous RSSIs less than or equal to the second predetermined threshold; and reporting the ratio to the base station.

According to a second aspect of embodiments of the present disclosure, a method for using RSSI in LAA is provided. The method comprises the following steps: receiving, at a base station, an RSSI from a user equipment, wherein the RSSI is measured by the user equipment based on determining whether an indication of a channel occupancy state is received from the base station; and using the received RSSI in authorizing secondary access for the user equipment.

In some embodiments, the RSSI is measured by the user equipment based on a determination that no indication of a channel occupancy state is received from the base station.

In some embodiments, receiving the RSSI from the user equipment comprises: receiving at least one instantaneous RSSI of a plurality of instantaneous RSSIs measured by the user equipment during a measurement period.

In some embodiments, receiving the RSSI from the user equipment further comprises: receiving a measurement time associated with the at least one instantaneous RSSI.

In some embodiments, the method further comprises: determining whether the channel occupancy state is a busy state or an idle state at the measurement time.

In some embodiments, the method further comprises: determining whether the number of received RSSIs is greater than zero in response to determining that the channel occupancy state is a busy state at the measurement time.

In some embodiments, using the RSSI in authorizing secondary access for the user equipment comprises: in response to determining that the number of received RSSIs is greater than zero, performing hidden node detection for the user equipment based on the received RSSIs.

In some embodiments, the method further comprises: determining whether an interference indication is received from the UE in response to determining that the channel occupancy status is a busy status at the measurement time.

In some embodiments, using the RSSI in authorizing secondary access for the user equipment comprises: in response to determining that the interference indication is received, performing hidden node detection for the user equipment based on the interference indication.

In some embodiments, the method further comprises: in response to determining that the channel occupancy state is a busy state for a portion of the measurement time and the channel occupancy state is an idle state for another portion of the measurement time, selecting an RSSI measured in the idle state from the received RSSIs; and calculating an average of the selected RSSIs.

In some embodiments, the method further comprises: comparing the selected RSSI to a first predetermined threshold; and calculating a ratio between the number of RSSIs that are greater than the first predetermined threshold and the number of RSSIs that are less than or equal to the first predetermined threshold.

In some embodiments, using the RSSI in authorizing secondary access for the user equipment comprises: performing carrier selection for the user equipment based on at least one of the average and the ratio.

In some embodiments, the method further comprises: in response to determining that the channel occupancy state is a busy state for a portion of the measurement time and the channel occupancy state is an idle state for another portion of the measurement time, selecting an RSSI measured in the busy state from the received RSSIs; and calculating a difference between each of the selected RSSIs and a corresponding reference signal received power, RSRP.

In some embodiments, using the RSSI in authorizing secondary access for the user equipment comprises: and based on the difference, performing hidden node detection for the user equipment.

In some embodiments, the method further comprises: configuring a muted subcarrier in a subframe transmitted to the user equipment such that the user equipment measures the plurality of instantaneous RSSIs on the muted subcarrier.

In some embodiments, the RSSI is measured by the user equipment based on determining that an indication of a channel occupancy state is received from the base station.

In some embodiments, the indication of the channel occupancy status indicates that the channel occupancy status is a busy status; and wherein receiving RSSI from the user equipment comprises: receiving at least one instantaneous RSSI of a plurality of instantaneous RSSIs measured by the user equipment during a measurement period.

In some embodiments, using the RSSI in authorizing secondary access for the user equipment comprises: performing hidden node detection for the user equipment based on the received RSSI.

In some embodiments, the indication of the channel occupancy state indicates that the channel occupancy state is an idle state; and wherein receiving RSSI from the user equipment comprises: receiving an average of the plurality of instantaneous RSSIs.

In some embodiments, receiving the RSSI from the user equipment further comprises: receiving a ratio between a number of instantaneous RSSIs greater than a second predetermined threshold and a number of instantaneous RSSIs less than or equal to the second predetermined threshold.

According to a third aspect of embodiments of the present disclosure, there is provided an apparatus for measuring and reporting RSSI in an LAA. The device includes: a determining unit configured to determine whether an indication of a channel occupancy state is received from a base station; a measurement unit configured to measure RSSI based on the determination; and a reporting unit configured to report the measured RSSI to the base station.

In some embodiments, the measurement unit is further configured to: in response to determining that the indication of the channel occupancy state is not received, measuring a plurality of instantaneous RSSIs during a measurement period.

In some embodiments, the apparatus further comprises: a first detection unit configured to detect a reference signal from a subframe from the base station in response to determining that the indication of the channel occupancy state is not received; and wherein the determining unit is further configured to determine that the channel occupancy status is a busy status in response to the first detecting unit detecting the reference signal.

In some embodiments, the measurement unit is further configured to: in response to determining that the indication of the channel occupancy state is received and that the indication of the channel occupancy state indicates that the channel occupancy state is a busy state, measuring a plurality of instantaneous RSSIs during a measurement period.

In some embodiments, the apparatus further comprises: a first calculation unit configured to calculate differences between the plurality of instantaneous RSSIs and respective reference signal received powers RSRP; and a first comparing unit configured to compare each of the difference values with a first predetermined threshold; and wherein the reporting unit is further configured to report at least one of the difference values to the base station or an interference indication to the base station in response to the at least one difference value being greater than the first predetermined threshold.

In some embodiments, the apparatus further comprises: a first detection unit configured to detect a reference signal from a subframe from the base station in response to determining that the indication of the channel occupancy state is not received; and wherein the reporting unit is further configured to report the plurality of instantaneous RSSIs to the base station in response to the first detection unit not detecting the reference signal.

In some embodiments, the measurement unit is further configured to: detecting a silent subcarrier pre-configured by the base station from a subframe from the base station; and in response to detecting the muted subcarriers, measuring the plurality of instantaneous RSSIs on the muted subcarriers.

In some embodiments, the reporting unit is further configured to: reporting a measurement time associated with the instantaneous RSSI to the base station.

In some embodiments, the measurement unit is further configured to: measuring a plurality of instantaneous RSSIs during a measurement period in response to determining that the indication of the channel occupancy state is received and that the indication of the channel occupancy state indicates that the channel occupancy state is an idle state; and calculating an average of the plurality of instantaneous RSSIs.

In some embodiments, the reporting unit is further configured to: reporting the average of the plurality of instantaneous RSSIs to the base station.

In some embodiments, the apparatus further comprises: a second comparing unit configured to compare the plurality of instantaneous RSSIs with a second predetermined threshold; and a second calculation unit configured to calculate a ratio between the number of instantaneous RSSIs greater than the second predetermined threshold and the number of instantaneous RSSIs less than or equal to the second predetermined threshold; and the reporting unit is further configured to report the ratio to the base station.

According to a fourth aspect of embodiments of the present disclosure, there is provided an apparatus for using RSSI in an LAA. The device includes: a receiving unit configured to receive an RSSI from a user equipment, wherein the RSSI is measured by the user equipment based on determining whether an indication of a channel occupancy state is received from a base station; and a using unit configured to use the received RSSI in authorized secondary access for the user equipment.

In some embodiments, the receiving unit is further configured to: receiving at least one instantaneous RSSI of a plurality of instantaneous RSSIs measured by the user equipment during a measurement period.

In some embodiments, the receiving unit is further configured to: receiving a measurement time associated with the at least one instantaneous RSSI.

In some embodiments, the using unit is further configured to: determining whether the channel occupancy state is a busy state or an idle state at the measurement time.

In some embodiments, the using unit is further configured to: determining whether the number of received RSSIs is greater than zero in response to determining that the channel occupancy state is a busy state at the measurement time.

In some embodiments, the using unit is further configured to: in response to determining that the number of received RSSIs is greater than zero, performing hidden node detection for the user equipment based on the received RSSIs.

In some embodiments, the using unit is further configured to: in response to determining that the number of received RSSIs is greater than zero, calculating a ratio between the number of received RSSIs and the number of predetermined sampling points; and determining whether the ratio is greater than a third predetermined threshold.

In some embodiments, the using unit is further configured to: in response to determining that the ratio is greater than the third predetermined threshold, performing hidden node detection for the user equipment based on the received RSSI.

In some embodiments, the using unit is further configured to: determining whether an interference indication is received from the UE in response to determining that the channel occupancy status is a busy status at the measurement time.

In some embodiments, the using unit is further configured to: in response to determining that the interference indication is received, performing hidden node detection for the user equipment based on the interference indication.

In some embodiments, the using unit is further configured to: in response to determining that the channel occupancy state is a busy state for a portion of the measurement time and the channel occupancy state is an idle state for another portion of the measurement time, selecting an RSSI measured in the idle state from the received RSSIs; and calculating an average of the selected RSSIs.

In some embodiments, the using unit is further configured to: comparing the selected RSSI to a first predetermined threshold; and calculating a ratio between the number of RSSIs that are greater than the first predetermined threshold and the number of RSSIs that are less than or equal to the first predetermined threshold.

In some embodiments, the using unit is further configured to: performing carrier selection for the user equipment based on at least one of the average and the ratio.

In some embodiments, the using unit is further configured to: in response to determining that the channel occupancy state is a busy state for a portion of the measurement time and the channel occupancy state is an idle state for another portion of the measurement time, selecting an RSSI measured in the busy state from the received RSSIs; and calculating a difference between each of the selected RSSIs and a corresponding reference signal received power, RSRP.

In some embodiments, the using unit is further configured to: and based on the difference, performing hidden node detection for the user equipment.

In some embodiments, the apparatus further comprises: a subcarrier configuration unit configured to configure muted subcarriers in a subframe transmitted to the user equipment so that the user equipment measures the plurality of instantaneous RSSIs on the muted subcarriers.

In some embodiments, the indication of the channel occupancy status indicates that the channel occupancy status is a busy status; and wherein the receiving unit is further configured to: receiving at least one instantaneous RSSI of a plurality of instantaneous RSSIs measured by the user equipment during a measurement period.

In some embodiments, the using unit is further configured to: performing hidden node detection for the user equipment based on the received RSSI.

In some embodiments, the indication of the channel occupancy state indicates that the channel occupancy state is an idle state; and wherein the receiving unit is further configured to: receiving an average of the plurality of instantaneous RSSIs.

In some embodiments, the receiving unit is further configured to: receiving a ratio between a number of instantaneous RSSIs greater than a second predetermined threshold and a number of instantaneous RSSIs less than or equal to the second predetermined threshold.

Embodiments of the present disclosure provide a detailed and complete solution for RSSI measurement and reporting, enabling an eNB to use the reported RSSI in LAA to at least address the problems of carrier selection and hidden node detection. Furthermore, the RSSI measurement and reporting mechanism according to embodiments of the present disclosure can keep the signaling overhead low.

Drawings

The features, advantages and other aspects of various embodiments of the present disclosure will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings, in which several embodiments of the present disclosure are shown by way of illustration and not limitation. In the drawings:

fig. 1 shows a flow diagram of a method of measuring and reporting RSSI in an LAA according to a first aspect of an embodiment of the present disclosure;

fig. 2 shows a flow chart of a method of using RSSI in an LAA according to a second aspect of an embodiment of the present disclosure;

fig. 3 schematically illustrates a flow of measuring, reporting and using RSSI in a first scenario according to an embodiment of the present disclosure;

fig. 4 schematically shows a flow of measuring, reporting and using RSSI in a second scenario according to an embodiment of the present disclosure;

fig. 5 schematically shows another flow of measuring, reporting and using RSSI in a second scenario according to an embodiment of the present disclosure;

fig. 6 shows a block diagram of an apparatus for measuring and reporting RSSI in an LAA according to a third aspect of an embodiment of the present disclosure; and

fig. 7 shows a block diagram of an apparatus using RSSI in an LAA according to a fourth aspect of an embodiment of the disclosure.

Detailed Description

The principles of the subject matter described herein will now be described with reference to a number of exemplary embodiments. It should be understood that these embodiments are described merely to enable those skilled in the art to better understand and thereby implement the subject matter described herein, and are not intended to limit the scope of the subject matter described herein in any way.

The term "base station" (BS) as used herein may refer to a node B (NodeB or NB), an evolved node B (eNodeB or eNB), a Remote Radio Unit (RRU), a Radio Head (RH), a Remote Radio Head (RRH), a relay, a low power node, such as a pico base station, a femto base station, and the like.

The term "user equipment" (UE) as used herein refers to any device capable of communicating with a BS. As an example, the UE may include a terminal, a Mobile Terminal (MT), a Subscriber Station (SS), a Portable Subscriber Station (PSS), a Mobile Station (MS), or an Access Terminal (AT).

In general, RSRP/RSRQ provides useful information to the eNB to help the eNB configure, activate, and de-configure cells. In LAA, due to the nature of medium sharing between different RATs and different LAA operators, RSRP/RSRQ may not be sufficient to deliver all information for channel selection and cell configuration/deconfiguration. For example, in LAA without hidden nodes, the signal to interference and noise ratio (SINR) experienced by data transmission is high due to LBT operation (i.e., transmission is only done when the channel is not occupied), while RSRQ may be much lower than the actual data SINR if it is measured via DRS colliding with Discovery Reference Signals (DRS) of other cells (depending on the details of the DRS transmission design).

Similarly, there may also be limitations on the information from the legacy RSSI, which may be more useful for channel selection, as it is measured via an LTE (or LAA) signal that is not able to reflect interference outside of the LAA burst. Therefore, the existing RSRP/RSRQ/RSSI measurements are not sufficient to be used for detection of the LAA channel selection and hidden node problem, which is crucial for operation in unlicensed spectrum. Based on the above discussion, new RRM measurements have to be introduced for channel selection and detection of hidden nodes in LAA systems.

Based on the measurement period, RSSI measurement for LAA can be divided into two phases: measurements in unoccupied periods before the LAA node acquires the channel, and measurements in occupied periods after the LAA node successfully acquires the channel.

In view of channel selection, the RSSI measurement should be based on a received power that does not include power from the reported cell, since the useful information is the channel load of other nodes. Therefore, it is preferable to measure the RSSI in a non-transmission period (i.e., a non-occupied period) of the serving eNB. In other words, the RSSI measured in the unoccupied period may be used to estimate the channel occupancy and load for carrier selection.

However, if the main purpose is to perform hidden node detection, then the RSSI measurements must include signal power from the potential hidden nodes. The probability that the RSSI includes signal power from a potential hidden node during the "on" period (i.e., the occupied period) of the reported cell may be quite high. Therefore, for the purpose of hidden node interference measurement, the RSSI measurement is preferably performed during the transmission period of the serving eNB. In other words, the RSSI measured during the occupied period may be used to identify the hidden node problem.

Thus, it is necessary to distinguish between RSSI measurements in the two transmission states. Furthermore, RSSI measurements for RRM measurements may be performed at multiple possible locations within a radio frame. For example, the measured RSSI may be different in the following scenario:

RSSI measurements are made during the transmission period of the eNB including the following subframes:

(1) transmitting a subframe of a DRS within a discovery window; or

(2) The eNB transmits a subframe of a downlink signal.

The RSSI measurement is made during a non-transmission period of the eNB including the following subframes:

(1) a subframe on which the DRS is not transmitted in the DRS period; or

(2) Subframes without downlink or uplink transmissions.

Each of the above scenarios may provide different values of RSSI, as the set of transmission nodes may be different in each scenario due to the LBT procedure used for channel access.

Although it may be beneficial to report different types of RSSI, this may result in significant signaling overhead, especially if RSSI is to be reported on a large number of unlicensed carriers.

Based on the above considerations, according to a first aspect of embodiments of the present disclosure, a method for measuring and reporting RSSI in licensed assisted access is provided. Fig. 1 shows a flow diagram of a method 100 for measuring and reporting RSSI in licensed assisted access according to a first aspect of an embodiment of the present disclosure. The method 100 may be performed by a UE in a wireless communication network, in particular, the method 100 may be performed by an apparatus 600 described later herein with reference to fig. 6.

The method 100 begins at step S110. In step S110, the UE determines whether an indication of a channel occupancy status is received from the serving eNB. In some embodiments, the eNB includes or does not include an indication of the channel occupancy status in a measurement control command sent to the UE, so the UE determines whether the indication of the channel occupancy status is included in the measurement control command after receiving the measurement control command from the serving eNB. It should be appreciated that the eNB may also include the indication of the channel occupancy state in other signaling sent to the UE, and the scope of the invention is not limited in this respect.

It is understood that the channel occupancy state includes a busy state or an idle state. The busy state indicates that the serving node eNB has successfully acquired the channel and is transmitting data, and the idle state indicates that the serving node eNB has not preempted the channel or that the serving node eNB has successfully acquired the channel but has no data to transmit. In some embodiments, the indication of the channel occupancy state comprises a 1-bit binary number. For example, a busy state is represented by "1", and an idle state is represented by "0".

Further, herein, the expressions "the channel occupying state is the busy state", "the channel is in the occupied period", and "the transmission period of the eNB" may be used interchangeably, and the expressions "the channel occupying state is the idle state", "the channel is in the non-occupied period", and "the non-transmission period of the eNB" may be used interchangeably.

Next, in step S120, the UE measures RSSI based on the determination. Subsequently, the UE reports the measured RSSI to the serving eNB at step S130. In some embodiments, the UE reports the measured RSSI to the serving eNB on a subframe pre-configured by the serving eNB.

According to a second aspect of embodiments of the present disclosure, a method for using RSSI in licensed assisted access is provided. Fig. 2 shows a flow diagram of a method 200 for using RSSI in licensed assisted access according to a second aspect of an embodiment of the present disclosure. The method 200 may be performed by an eNB in a wireless communication network, and in particular, the method 200 may be performed by an apparatus 700 described later herein with reference to fig. 7.

The method 200 begins at step S210. At step S210, the eNB receives an RSSI from the UE, which is measured by the UE based on determining whether an indication of a channel occupancy status is received from the eNB.

As previously described, the eNB may include or not include the indication of the channel occupancy state in the measurement control command sent to the UE, so the UE determines whether the indication of the channel occupancy state is included in the measurement control command after receiving the measurement control command from the serving eNB.

In some embodiments, the measurement control commands comprise at least one of: indication of channel occupancy state, measurement timing, measurement period, measurement granularity, energy detection threshold; wherein the measurement timing indicates a time at which the UE should start RSSI measurement, the measurement period indicates a time period in which the UE should perform RSSI measurement, and the measurement granularity indicates a number of times the UE should perform RSSI measurement in the measurement period. It is understood that based on the measurement period and the measurement granularity, the UE may determine the point in time (also referred to as a sampling point) at which to perform the RSSI measurement. Further, the energy detection threshold is a threshold employed when energy detection is performed at the eNB. Since energy detection procedures are known in the art, the eNB may configure any suitable energy detection threshold according to the known procedures.

Subsequently, the eNB uses the received RSSI in the LAA for the UE at step S220.

The details of the

methods

100 and 200 will be described below in connection with two specific scenarios.

First scene

In a first scenario, the eNB does not indicate the channel occupancy status to the UE, i.e. does not send an indication of the channel occupancy status to the UE. Accordingly, the UE determines that no indication of the channel occupancy state is received. Thus, the UE will not know whether the serving eNB is in a transmission state or a non-transmission state. In this case, the UE may employ any one of the following three options to measure and report RSSI.

First option

In a first option, the UE measures a plurality of instantaneous RSSIs for a measurement period in response to determining that no indication of a channel occupancy state is received. Specifically, in the first option, the UE may measure and report the RSSI in the following two ways.

In a first approach, in response to determining that no indication of a channel occupancy status is received, the UE detects a reference signal from a subframe from a serving eNB and, in response to detecting the reference signal, determines that the channel occupancy status is a busy status. In some embodiments, the reference signal comprises at least one of: CRS, DRS, channel state information reference signal (CSI-RS). Based on the reference signal, the UE may determine an average of the received signal power over all REs carrying the reference signal within a particular symbol, i.e., RSRP. Thus, the UE may calculate differences between a plurality of instantaneous RSSIs and respective RSRPs, compare each of the differences to a first predetermined threshold, and report at least one of the differences to the serving eNB in response to the at least one difference being greater than the first predetermined threshold. It will be appreciated that the first predetermined threshold may be preconfigured by the serving eNB. In some embodiments, the first predetermined threshold is an energy detection threshold received from a measurement control command. In this way, the UE will not report the difference to the serving eNB when the difference is less than the first predetermined threshold, thereby reducing feedback overhead. Moreover, to further reduce feedback overhead, in response to at least one of the differences being greater than the first predetermined threshold, the UE may not report the at least one difference to the serving eNB, but only report a corresponding interference indication to the serving eNB. It will be appreciated that the UE generates an interference indication whenever a difference is greater than the first predetermined threshold, and thus the number of interference indications is the same as the number of differences greater than the first predetermined threshold. In some embodiments, the interference indication comprises a 1-bit binary number. For example, taking a "1" indicates that interference is present.

In a second approach, in response to determining that no indication of the channel occupancy state is received, the UE detects a reference signal from a subframe from the serving eNB and, in response to not detecting the reference signal, reports the plurality of instantaneous RSSIs to the serving eNB. In this second approach, the UE does not detect the reference signal, for example, due to a detection error or because the eNB only transmits data during this period, and thus the UE cannot know the channel occupancy state at this time. Therefore, the UE feeds back all instantaneous RSSI to the eNB. In this case, the RSSI measured on certain subframes may include the desired signal (i.e., the power of the serving cell of the UE) as well as the power from other cells (i.e., interference), since the eNB may not transmit a reference signal on these subframes during the channel occupancy state being busy.

Furthermore, in the first and second manners described above, in addition to reporting the instantaneous RSSI to the eNB, the UE may also report a measurement time associated with the instantaneous RSSI to the eNB.

In addition, for the first and second aspects, the eNB may perform the following operations, respectively.

For the first mode, the eNB receives at least one instantaneous RSSI of a plurality of instantaneous RSSIs measured by the UE during the measurement period. Further, the eNB may also receive a measurement time associated with the at least one instantaneous RSSI from the UE.

Then, the eNB determines whether the channel occupancy state is a busy state or an idle state at the measurement time. The eNB further determines whether the number of received RSSIs is greater than zero if it is determined that the channel occupancy state is a busy state at the measurement time. If the number of received RSSIs is greater than zero, it may be determined that the received RSSI was measured and reported by the UE in the first manner described above.

In addition, as described previously, the measurement period and the measurement granularity of the RSSI are pre-configured by the eNB. In other words, the sampling points at which the UE performs RSSI measurements, and the number of sampling points, are predetermined by the eNB. Thus, in response to determining that the number of received RSSIs is greater than zero, the eNB may further calculate a ratio between the number of received RSSIs and the number of predetermined sampling points, and determine whether the ratio is greater than a third predetermined threshold. Further, the eNB performs hidden node detection for the UE based on the received RSSI if it is determined that the ratio is greater than a third predetermined threshold. The third predetermined threshold may be any suitable value, for example, any value between 30% and 60%. Furthermore, as described above for the first approach to the first option of the first scenario, when the UE determines that an indication of a channel occupancy state is received and the indication of the channel occupancy state indicates that the channel occupancy state is a busy state, the UE may calculate differences between a plurality of instantaneous RSSIs and respective RSRPs, compare each of the differences to a predetermined threshold, and generate an interference indication each time a difference is greater than the predetermined threshold. Thus, instead of reporting to the eNB a difference greater than the predetermined threshold, the UE reports to the eNB a corresponding interference indication. In this regard, if the eNB determines that the channel occupancy status is a busy status at the measurement time, the eNB may further determine whether an interference indication is received from the UE indicating that a difference between the respective instantaneous RSSI and the corresponding RSRP is greater than a predetermined threshold. Thus, in response to determining that the interference indication is received, the eNB may determine that the UE measures RSSI in the first manner described above.

Since the RSSI measured and reported by the UE in the first manner does not include the power of the serving cell of the UE, but only includes power from other cells (i.e., interference), the eNB may perform hidden node detection for the UE based on the received RSSI or interference indication. For example, the eNB may compare the received RSSI to the RSSI measured by the eNB itself or to a predetermined threshold, and may determine that a hidden node problem exists at the UE if the received RSSI is greater than the RSSI measured by the eNB itself or to the predetermined threshold.

For the above second manner, in response to determining that the channel occupancy state is a busy state for a part of the measurement time and the channel occupancy state is an idle state for another part of the measurement time, the eNB selects the RSSI measured in the idle state from the received RSSIs and calculates an average value of the selected RSSIs. Further, the eNB compares the selected RSSI to a first predetermined threshold and calculates a ratio between the number of RSSIs that are greater than the first predetermined threshold and the number of RSSIs that are less than or equal to the first predetermined threshold. It will be appreciated that this ratio may be indicative of the channel occupancy, and is therefore also referred to herein as the duty cycle. Thus, the eNB may make carrier selection for the UE based on at least one of the calculated average and duty cycle. Further, in some embodiments, the first predetermined threshold is an energy detection threshold employed in performing energy detection at the eNB.

In addition, it should be understood that since the RSSI measured and reported by the UE in the second manner may include not only power from other cells (i.e., interference), but also power of the serving cell of the UE, the eNB preferably does not perform hidden node detection for the UE based on the received RSSI.

Fig. 3 schematically shows a flow of the UE measuring and reporting RSSI in the second way described above and the eNB using RSSI in the first scenario. As shown in fig. 3, the eNB configures the UE to measure the RSSI by transmitting a measurement control command to the UE in step 310. In step 320, the UE measures the instantaneous RSSI in response to the measurement control command. Subsequently, in step 330, the UE reports the measured instantaneous RSSI to the eNB.

On the eNB side, the eNB calculates an average value of instantaneous RSSI (i.e., average RSSI) and a duty ratio in step 340. Then, in step 350, the eNB performs hidden node detection based on the measured instantaneous RSSI in the occupied period and/or carrier selection based on the average value (i.e., average RSSI) and duty cycle for the unoccupied period. Thereafter, the eNB notifies the UE of the operation channel in step 360. As such, the UE may conduct conventional LTE communications on the operating channel.

It should be understood that the flow shown in fig. 3 is merely illustrative and not restrictive, and that the second manner described above may take more or less operations than those shown in fig. 3.

Second option

In the second option, the UE does not determine the channel occupancy state by detecting the reference signal as in the first option. To enable the UE to measure received signal power excluding the power of the serving cell, the eNB configures muted subcarriers in a subframe transmitted to the UE such that the configured subcarriers are muted during data transmission. Thus, the UE detects the preconfigured muted subcarriers from the subframe from the serving eNB and measures a plurality of instantaneous RSSIs on the muted subcarriers in response to detecting the muted subcarriers. The UE then reports the measured multiple instantaneous RSSIs to the serving eNB over a subframe pre-configured by the serving eNB.

Furthermore, in a second option, the eNB should consider at least one of the following factors when configuring the muted subcarriers.

(1) The positions of the muted subcarriers from different cells are made non-conflicting, i.e., the muted subcarriers from different cells are made orthogonal to each other. In some embodiments, the muted subcarriers from different cells are made orthogonal to each other by time-domain or frequency-domain multiplexing. In some embodiments, subcarriers with different index numbers on the same symbol are configured as muted subcarriers for different cells in the frequency domain. For example, in the case where one symbol includes 12 subcarriers, subcarriers having indices of 1 and 7 are configured as the muted subcarriers from one cell, and subcarriers having indices of 2 and 8 are configured as the muted subcarriers from another cell. In some embodiments, in the time domain, subcarriers on different symbols are configured as muted subcarriers for different cells. For example, in the time domain, any two subcarriers on one symbol are configured as muted subcarriers from one cell, and any two subcarriers on another symbol are configured as muted subcarriers from another cell. Further, the location of the muted subcarriers may be tied to the cell identity, thereby implicitly at least the location of the muted subcarriers.

(2) Such that the location of the muted subcarriers does not conflict with the location of reference signals, e.g., Primary Synchronization Signals (PSS), Secondary Synchronization Signals (SSS), CRS, CSI-RS, Positioning Reference Signals (PRS), etc.

(3) The number of OFDM symbols that need to silence the subcarriers for measurement needs to be considered to trade off between measurement accuracy and resource overhead.

In addition, for the second option described above, the eNB may take the following actions.

Specifically, the eNB receives a plurality of instantaneous RSSIs measured by the UE during a measurement period. Further, the eNB may also receive a measurement time associated with the instantaneous RSSI from the UE.

Then, the eNB determines whether the channel occupancy state is a busy state or an idle state at the measurement time. Further, if it is determined that the channel occupying state is a busy state for a part of the measurement time and the channel occupying state is an idle state for another part of the measurement time, the eNB selects the RSSI measured in the busy state from the received RSSIs. Thus, the eNB may perform hidden node detection for the UE based on the selected RSSI. For example, the eNB may compare the selected RSSI to the RSSI measured by the eNB itself or to a predetermined threshold, and may determine that a hidden node problem exists at the UE if the selected RSSI is greater than the RSSI measured by the eNB itself or to the predetermined threshold.

In addition, similar to the first manner in the first option described above, if it is determined that the channel occupancy state is a busy state at the measurement time and it is determined that the number of received RSSIs is greater than zero, the eNB may further calculate a ratio between the number of received RSSIs and the number of predetermined sampling points, and determine whether the ratio is greater than a predetermined threshold. Further, the eNB performs hidden node detection for the UE based on the received RSSI if it is determined that the ratio is greater than the predetermined threshold.

On the other hand, if it is determined that the channel occupying state is a busy state for a part of the measurement time and the channel occupying state is an idle state for another part of the measurement time, the eNB selects the RSSI measured in the idle state from the received RSSIs. Further, the eNB may calculate an average of the selected RSSIs and calculate a duty ratio as described above. Thus, the eNB may make carrier selection for the UE based on at least one of the calculated average and duty cycle.

In addition, it will be appreciated that the RSSI measured and reported with this second option is an accurate instantaneous RSSI that includes only interference from other cells and does not include the power of the serving cell. Furthermore, in the second option, the UE does not need to detect the reference signal, thereby saving power.

Third option

In a third option, the UE takes the same operations as the second way in the first option described above to measure and report multiple instantaneous RSSI, except that the channel occupancy state is determined by detecting the reference signal. Furthermore, in this third option, in addition to reporting the instantaneous RSSI to the eNB, the UE may also report the measurement time associated with the instantaneous RSSI to the eNB.

Accordingly, the eNB may also take the same operations as for the second approach in the first option described above.

It will be appreciated that in this third option, the eNB need not indicate the channel occupancy status to the UE. In addition, the UE does not need to distinguish between the RSSI measured in the channel-busy state and the RSSI measured in the channel-idle state, thereby simplifying the operation of the UE.

Second scenario

In a second scenario, the eNB includes an indication of the channel occupancy status in the measurement control command. Accordingly, the UE determines that there is an indication of the channel occupancy state in the measurement control command. Thus, the UE will know whether the serving eNB is in a transmitting state or a non-transmitting state. In this case, the UE may measure and report the RSSI in either of the following two ways depending on whether the serving eNB is in a transmission state or a non-transmission state.

Fig. 4 schematically shows a flow of the UE measuring and reporting RSSI in a first manner and the eNB using RSSI in a second scenario. As shown in fig. 4, the eNB configures the UE to measure the RSSI by transmitting a measurement control command to the UE in step 410.

In step 420, in response to determining that the indication of the channel occupancy state is received and that the indication of the channel occupancy state indicates that the channel occupancy state is a busy state, the UE measures a plurality of instantaneous RSSIs for a measurement period.

Subsequently, in step 430, the UE reports the measured instantaneous RSSI to the eNB. Specifically, the UE may perform the following operations in step 430. First, the UE calculates the difference between a plurality of instantaneous RSSIs and the corresponding RSRPs. Next, the UE compares each of the difference values with a first predetermined threshold. Then, in response to at least one of the difference values being greater than the first predetermined threshold, the UE reports the at least one difference value to the serving eNB. This first predetermined threshold may be preconfigured by the serving eNB, similar to the first approach in the first scenario above. In some embodiments, the first predetermined threshold is an energy detection threshold received from a measurement control command. In this way, the UE will not report the difference to the serving eNB when the difference is less than the first predetermined threshold, thereby reducing feedback overhead. Further, similar to the first approach in the first scenario above, in order to further reduce feedback overhead, in response to at least one of the differences being greater than the first predetermined threshold, the UE may not report the at least one difference to the serving eNB, but may only report an interference indication to the serving eNB.

On the eNB side, the eNB performs hidden node detection based on the instantaneous RSSI measured in the occupied period in step 440. The eNB may perform the operation of detecting the hidden node by using the same operation as the first mode in the first option in the first scenario, and thus details are not repeated.

Thereafter, the eNB notifies the UE of the operation channel in step 450. As such, the UE may conduct conventional LTE communications on the operating channel.

It should be understood that the flow shown in FIG. 4 is merely illustrative and not restrictive, and that the first approach described above may take more or less operations than shown in FIG. 4

Fig. 5 schematically shows a flow of the UE measuring and reporting RSSI in a second way and the eNB using RSSI in a second scenario. As shown in fig. 5, the eNB configures the UE to measure the RSSI by transmitting a measurement control command to the UE in step 510.

In step 520, the UE measures a plurality of instantaneous RSSIs for a measurement period in response to determining that the indication of the channel occupancy state is received and that the indication of the channel occupancy state indicates that the channel occupancy state is an idle state.

Next, in step 530, the UE calculates an average value of the plurality of instantaneous RSSIs (i.e., an average RSSI). Further, in step 530, the UE may also compare the plurality of instantaneous RSSIs with a second predetermined threshold and calculate a ratio (i.e., duty cycle) between the number of instantaneous RSSIs that are greater than the second predetermined threshold and the number of instantaneous RSSIs that are less than or equal to the second predetermined threshold. The second predetermined threshold may be preconfigured by the serving eNB. In some embodiments, the second predetermined threshold is an energy detection threshold received from a measurement control command. Alternatively, the second predetermined threshold may be any other suitable value.

Subsequently, in step 540, the UE reports the average RSSI and duty cycle to the eNB. It will be appreciated that the average RSSI and duty cycle may reflect the availability of channels for carrier selection.

On the eNB side, the eNB performs carrier selection based on the average RSSI and duty cycle in the unoccupied period in step 550. Thereafter, the eNB notifies the UE of the operation channel in step 560. As such, the UE may conduct conventional LTE communications on the operating channel.

It should be understood that the flow shown in fig. 5 is merely illustrative and not restrictive, and that the second approach described above may take more or less operations than those shown in fig. 3.

Furthermore, it can be appreciated that since in this second approach, the UE only reports the average RSSI and duty cycle in the unoccupied period to the eNB, the limitation reduces feedback overhead.

In addition, in this second scenario, since the eNB needs to indicate the channel occupancy status to the UE, and the measurement period during which the UE performs RSSI measurement is also configured by the eNB, the eNB does not transmit data to the UE within the measurement period preferred by the eNB.

According to a third aspect of embodiments of the present disclosure, there is provided an apparatus for measuring and reporting RSSI in an LAA. Fig. 6 shows a block diagram of an apparatus 600 for measuring and reporting RSSI in an LAA according to a third aspect of an embodiment of the present disclosure. Apparatus 600 may be implemented in a UE, for example.

As shown in fig. 6, the apparatus 600 includes: a determining unit 610 configured to determine whether an indication of a channel occupancy state is received from a base station; a measuring unit 620 configured to measure RSSI based on the determination; and a reporting unit 630 configured to report the measured RSSI to the base station.

In some embodiments, the measurement unit 620 is further configured to: in response to determining that the indication of the channel occupancy state is not received, measuring a plurality of instantaneous RSSIs during a measurement period.

In some embodiments, the apparatus 600 further comprises: a first detection unit configured to detect a reference signal from a subframe from the base station in response to determining that the indication of the channel occupancy state is not received; and wherein the determining unit 610 is further configured to determine that the channel occupancy status is a busy status in response to the first detecting unit detecting the reference signal.

In some embodiments, the measurement unit 620 is further configured to: in response to determining that the indication of the channel occupancy state is received and that the indication of the channel occupancy state indicates that the channel occupancy state is a busy state, measuring a plurality of instantaneous RSSIs during a measurement period.

In some embodiments, the apparatus 600 further comprises: a first calculation unit configured to calculate differences between the plurality of instantaneous RSSIs and respective reference signal received powers RSRP; and a first comparing unit configured to compare each of the difference values with a first predetermined threshold; and wherein the reporting unit 630 is further configured to report at least one of the difference values to the base station or an interference indication to the base station in response to the at least one difference value being greater than the first predetermined threshold.

In some embodiments, the apparatus 600 further comprises: a first detection unit configured to detect a reference signal from a subframe from the base station in response to determining that the indication of the channel occupancy state is not received; and wherein the reporting unit 630 is further configured to report the plurality of instantaneous RSSIs to the base station in response to the first detection unit not detecting the reference signal.

In some embodiments, the measurement unit 620 is further configured to: detecting a silent subcarrier pre-configured by the base station from a subframe from the base station; and in response to detecting the muted subcarriers, measuring the plurality of instantaneous RSSIs on the muted subcarriers.

In some embodiments, the reporting unit 630 is further configured to: reporting a measurement time associated with the instantaneous RSSI to the base station.

In some embodiments, the measurement unit 620 is further configured to: measuring a plurality of instantaneous RSSIs during a measurement period in response to determining that the indication of the channel occupancy state is received and that the indication of the channel occupancy state indicates that the channel occupancy state is an idle state; and calculating an average of the plurality of instantaneous RSSIs.

In some embodiments, the reporting unit 630 is further configured to: reporting the average of the plurality of instantaneous RSSIs to the base station.

In some embodiments, the apparatus 600 further comprises: a second comparing unit configured to compare the plurality of instantaneous RSSIs with a second predetermined threshold; and a second calculation unit configured to calculate a ratio between the number of instantaneous RSSIs greater than the second predetermined threshold and the number of instantaneous RSSIs less than or equal to the second predetermined threshold; and the reporting unit 630 is further configured to report the ratio to the base station.

According to a fourth aspect of embodiments of the present disclosure, there is provided an apparatus for using RSSI in an LAA. Fig. 7 shows a block diagram of an apparatus 700 for using RSSI in LAA according to a fourth aspect of an embodiment of the present disclosure. The apparatus 700 may be implemented in a base station, for example.

As shown in fig. 7, the apparatus 700 includes: a receiving unit 710 configured to receive an RSSI from a user equipment, wherein the RSSI is measured by the user equipment based on determining whether an indication of a channel occupancy state is received from a base station; and a using unit 720 configured to use the received RSSI in authorized secondary access for the user equipment.

In some embodiments, the receiving unit 710 is further configured to: receiving at least one instantaneous RSSI of a plurality of instantaneous RSSIs measured by the user equipment during a measurement period.

In some embodiments, the receiving unit 710 is further configured to: receiving a measurement time associated with the at least one instantaneous RSSI.

In some embodiments, the usage unit 720 is further configured to: determining whether the channel occupancy state is a busy state or an idle state at the measurement time.

In some embodiments, the usage unit 720 is further configured to: determining whether the number of received RSSIs is greater than zero in response to determining that the channel occupancy state is a busy state at the measurement time.

In some embodiments, the usage unit 720 is further configured to: in response to determining that the number of received RSSIs is greater than zero, performing hidden node detection for the user equipment based on the received RSSIs.

In some embodiments, the usage unit 720 is further configured to: determining whether an interference indication is received from the UE in response to determining that the channel occupancy status is a busy status at the measurement time.

In some embodiments, the usage unit 720 is further configured to: in response to determining that the interference indication is received, performing hidden node detection for the user equipment based on the interference indication.

In some embodiments, the usage unit 720 is further configured to: in response to determining that the channel occupancy state is a busy state for a portion of the measurement time and the channel occupancy state is an idle state for another portion of the measurement time, selecting an RSSI measured in the idle state from the received RSSIs; and calculating an average of the selected RSSIs.

In some embodiments, the usage unit 720 is further configured to: comparing the selected RSSI to a first predetermined threshold; and calculating a ratio between the number of RSSIs that are greater than the first predetermined threshold and the number of RSSIs that are less than or equal to the first predetermined threshold.

In some embodiments, the usage unit 720 is further configured to: performing carrier selection for the user equipment based on at least one of the average and the ratio.

In some embodiments, the usage unit 720 is further configured to: in response to determining that the channel occupancy state is a busy state for a portion of the measurement time and the channel occupancy state is an idle state for another portion of the measurement time, selecting an RSSI measured in the busy state from the received RSSIs; and calculating a difference between each of the selected RSSIs and a corresponding reference signal received power, RSRP.

In some embodiments, the usage unit 720 is further configured to: and based on the difference, performing hidden node detection for the user equipment.

In some embodiments, the apparatus 700 further comprises: a subcarrier configuration unit configured to configure muted subcarriers in a subframe transmitted to the user equipment so that the user equipment measures the plurality of instantaneous RSSIs on the muted subcarriers.

In some embodiments, the indication of the channel occupancy status indicates that the channel occupancy status is a busy status; and wherein the receiving unit 710 is further configured to: receiving at least one instantaneous RSSI of a plurality of instantaneous RSSIs measured by the user equipment during a measurement period.

In some embodiments, the usage unit 720 is further configured to: performing hidden node detection for the user equipment based on the received RSSI.

In some embodiments, the indication of the channel occupancy state indicates that the channel occupancy state is an idle state; and wherein the receiving unit 710 is further configured to: receiving an average of the plurality of instantaneous RSSIs.

In some embodiments, the receiving unit 710 is further configured to: receiving a ratio between a number of instantaneous RSSIs greater than a second predetermined threshold and a number of instantaneous RSSIs less than or equal to the second predetermined threshold.

In general, the various example embodiments of this disclosure may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. Certain aspects may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device. While aspects of embodiments of the disclosure have been illustrated or described as block diagrams, flow charts, or using some other pictorial representation, it is well understood that the blocks, apparatus, systems, techniques or methods described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.

Also, blocks in the flow diagrams may be viewed as method steps, and/or as operations that result from operation of computer program code, and/or as a plurality of coupled logic circuit elements understood to perform the associated functions. For example, embodiments of the present disclosure include a computer program product comprising a computer program tangibly embodied on a machine-readable medium, the computer program containing program code configured to implement the above-described methods.

Within the context of this disclosure, a machine-readable medium may be any tangible medium that can contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device. The machine-readable medium may be a machine-readable signal medium or a machine-readable storage medium. A machine-readable medium may include, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination thereof. More detailed examples of a machine-readable storage medium include an electrical connection having one or more wires, a portable computer diskette, a hard disk, a Random Access Memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical storage device, a magnetic storage device, or any suitable combination thereof.

Computer program code for implementing the methods of the present disclosure may be written in one or more programming languages. These computer program codes may be provided to a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus, such that the program codes, when executed by the computer or other programmable data processing apparatus, cause the functions/acts specified in the flowchart and/or block diagram block or blocks to be performed. The program code may execute entirely on the computer, partly on the computer, as a stand-alone software package, partly on the computer and partly on a remote computer or entirely on the remote computer or server.

Additionally, while operations are depicted in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. In some cases, multitasking or parallel processing may be beneficial. Likewise, while the above discussion contains certain specific implementation details, this should not be construed as limiting the scope of any invention or claims, but rather as describing particular embodiments that may be directed to particular inventions. Certain features that are described in this specification in the context of separate embodiments can also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment can also be implemented in multiple embodiments separately or in any suitable subcombination.

Various modifications, adaptations, and exemplary embodiments of the foregoing disclosure may become apparent to those skilled in the relevant arts in view of the foregoing description, when read in conjunction with the accompanying drawings. Any and all modifications will still fall within the scope of the non-limiting and exemplary embodiments of this disclosure. Moreover, the foregoing description and drawings present instructive benefits, and other embodiments of the present disclosure set forth herein will occur to those skilled in the art to which these embodiments of the present disclosure pertain.

It is to be understood that the embodiments of the disclosure are not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

Claims

1. A method for measuring and reporting received signal strength indication, RSSI, in licensed assisted access, comprising:

determining whether an indication of a channel occupancy state is received from a base station;

in response to determining that the indication of the channel occupancy state has not been received,

detecting the muted subcarriers pre-configured by the base station from the subframes from the base station, an

In response to detecting the muted subcarriers, measuring a plurality of instantaneous RSSIs on the muted subcarriers during a measurement period; and

reporting the measured RSSI to the base station.

2. The method of claim 1, further comprising:

in response to determining that the indication of the channel occupancy state is not received, detecting a reference signal from a subframe from the base station; and

in response to detecting the reference signal, determining that the channel occupancy state is a busy state.

3. The method of claim 1, further comprising:

in response to determining that the indication of the channel occupancy state is received and that the indication of the channel occupancy state indicates that the channel occupancy state is a busy state, measuring a plurality of instantaneous RSSIs during a measurement period.

4. The method of claim 2 or 3, wherein reporting the measured RSSI to the base station comprises:

calculating differences between the plurality of instantaneous RSSIs and respective Reference Signal Received Powers (RSRPs);

comparing each of the differences to a first predetermined threshold; and

reporting at least one of the differences to the base station or reporting an interference indication to the base station in response to the at least one of the differences being greater than the first predetermined threshold.

5. The method of claim 1, further comprising:

reporting the plurality of instantaneous RSSIs to the base station in response to not detecting the reference signal.

6. The method of claim 1, wherein reporting the measured RSSI to the base station further comprises:

reporting a measurement time associated with the instantaneous RSSI to the base station.

7. The method of claim 1, further comprising:

measuring a plurality of instantaneous RSSIs during a measurement period in response to determining that the indication of the channel occupancy state is received and that the indication of the channel occupancy state indicates that the channel occupancy state is an idle state; and

calculating an average of the plurality of instantaneous RSSIs.

8. The method of claim 7, wherein reporting the measured RSSI to the base station comprises:

reporting the average of the plurality of instantaneous RSSIs to the base station.

9. The method of claim 8, further comprising:

comparing the plurality of instantaneous RSSIs to a second predetermined threshold;

calculating a ratio between the number of instantaneous RSSIs greater than the second predetermined threshold and the number of instantaneous RSSIs less than or equal to the second predetermined threshold; and

reporting the ratio to the base station.

10. A method for using received signal strength indication, RSSI, in authorizing assisted access, comprising:

configuring, at a base station, a muted subcarrier in a subframe transmitted to a user equipment;

receiving, from the user equipment, a plurality of instantaneous RSSIs measured by the user equipment on the muted subcarriers, wherein the RSSIs are measured by the user equipment based on determining that no indication of a channel occupancy state is received from the base station; and

using the received RSSI in authorizing secondary access for the user equipment.

11. The method of claim 10, wherein receiving RSSI from a user equipment comprises:

receiving at least one instantaneous RSSI of a plurality of instantaneous RSSIs measured by the user equipment during a measurement period.

12. The method of claim 11, wherein receiving RSSI from a user equipment further comprises:

receiving a measurement time associated with the at least one instantaneous RSSI.

13. The method of claim 12, further comprising:

determining whether the channel occupancy state is a busy state or an idle state at the measurement time.

14. The method of claim 13, further comprising:

determining whether the number of received RSSIs is greater than zero in response to determining that the channel occupancy state is a busy state at the measurement time.

15. The method of claim 14, wherein using the RSSI in authorized secondary access for the user equipment comprises:

in response to determining that the number of received RSSIs is greater than zero, performing hidden node detection for the user equipment based on the received RSSIs.

16. The method of claim 13, further comprising:

determining whether an interference indication is received from the user equipment in response to determining that the channel occupancy state is a busy state at the measurement time.

17. The method of claim 16, wherein using the RSSI in authorized secondary access for the user equipment comprises:

in response to determining that the interference indication is received, performing hidden node detection for the user equipment based on the interference indication.

18. The method of claim 15, further comprising:

in response to determining that the channel occupancy state is a busy state for a portion of the measurement time and the channel occupancy state is an idle state for another portion of the measurement time, selecting an RSSI measured in the idle state from the received RSSIs; and

an average of the selected RSSIs is calculated.

19. The method of claim 18, further comprising:

comparing the selected RSSI to a first predetermined threshold; and

calculating a ratio between a number of RSSIs greater than the first predetermined threshold and a number of RSSIs less than or equal to the first predetermined threshold.

20. The method of claim 19, wherein using the RSSI in authorized secondary access for the user equipment comprises:

performing carrier selection for the user equipment based on at least one of the average and the ratio.

21. The method of claim 15, further comprising:

in response to determining that the channel occupancy state is a busy state for a portion of the measurement time and the channel occupancy state is an idle state for another portion of the measurement time, selecting an RSSI measured in the busy state from the received RSSIs; and

a difference between each of the selected RSSIs and a respective reference signal received power, RSRP, is calculated.

22. The method of claim 21, wherein using the RSSI in authorized secondary access for the user equipment comprises:

and based on the difference, performing hidden node detection for the user equipment.

23. The method of claim 11, wherein the RSSI is measured by the user equipment based on determining that an indication of a channel occupancy state is received from the base station.

24. The method of claim 23, wherein the indication of the channel occupancy status indicates that the channel occupancy status is a busy status; and is

Wherein receiving RSSI from the user equipment comprises:

25. The method of claim 24, wherein using the RSSI in authorized secondary access for the user equipment comprises:

performing hidden node detection for the user equipment based on the received RSSI.

26. The method of claim 23, wherein the indication of the channel occupancy state indicates that the channel occupancy state is an idle state; and is

Wherein receiving RSSI from the user equipment comprises:

receiving an average of the plurality of instantaneous RSSIs.

27. The method of claim 26, wherein receiving RSSI from a user equipment further comprises:

receiving a ratio between a number of instantaneous RSSIs greater than a second predetermined threshold and a number of instantaneous RSSIs less than or equal to the second predetermined threshold.

28. The method of claim 27, wherein using the RSSI in authorized secondary access for the user equipment comprises:

29. The method of claim 15, further comprising:

in response to determining that the number of received RSSIs is greater than zero, calculating a ratio between the number of received RSSIs and the number of predetermined sampling points; and

it is determined whether the ratio is greater than a third predetermined threshold.

30. The method of claim 29, wherein using the RSSI in authorized secondary access for the user equipment comprises:

in response to determining that the ratio is greater than the third predetermined threshold, performing hidden node detection for the user equipment based on the received RSSI.

31. An apparatus for measuring and reporting received signal strength indication, RSSI, in licensed assisted access, comprising:

a determining unit configured to determine whether an indication of a channel occupancy state is received from a base station;

a measurement unit configured to, in response to determining that no indication of a channel occupancy state is received,

a reporting unit configured to report the measured RSSI to the base station.

32. An apparatus for using Received Signal Strength Indication (RSSI) in authorizing secondary access, comprising:

a configuration unit configured to configure, at a base station, muted subcarriers in a subframe transmitted to a user equipment;

a receiving unit configured to receive from the user equipment a plurality of instantaneous RSSIs measured by the user equipment on the muted subcarriers, wherein the RSSIs are measured by the user equipment based on determining whether an indication of a channel occupancy state is received from the base station; and

a using unit configured to use the received RSSI in authorized secondary access for the user equipment.