CN105323811A - Channel switching method - Google Patents

Abstract

A method for channel switching, the method comprising: a base station eNB triggers an aperiodic measurement gap in a radio frame; in the aperiodic measurement gap, at the start of the transceiver tuning time, the eNB and the user UE will be interfered with by the frequency of the carrier The point is switched to the new frequency point indicated by the eNB; from the end of the transceiver tuning time to the end of the aperiodic measurement gap, the eNB continues to transmit the signal of the interfered carrier on the new frequency point, and the UE corresponds to the new frequency point monitor on the channel. After applying the embodiment of the present invention, channel switching is completed in the LTE-U equipment.

Description

A method of channel switching

technical field

The present application relates to the technical field of communications, and more specifically, to a channel switching method.

Background technique

Judging from the status quo of spectrum division, the total amount of unlicensed spectrum is considerable compared with the total amount of licensed spectrum for mobile communications. In the case of increasingly tight licensed dedicated spectrum resources, unlicensed spectrum is of great importance to operators. value is becoming more and more important. At the 3GPPRAN62 plenary meeting, the manuscript RP-132085 proposed the research project of integrating the license-free spectrum into LTE. In June 2014, 3GPP held a special seminar on introducing license-free spectrum. It can be predicted that a very important research direction of 3GPP after Release12 is to integrate the unlicensed spectrum into LTE to form the LTE-U (LTE in Unlicensed Spectrum) standard.

The carrier on the license-free frequency band is limited by the transmission power, and generally has a small coverage area. In the LTE system, it usually cannot be independently networked. It needs to work with the assistance of the carrier in the licensed frequency band in the form of carrier aggregation. Although there may be many available carriers on the unlicensed frequency band, due to the existence of other devices, it may not be the optimal choice to design the system operating bandwidth according to the number of available carriers. A possible scenario is that the bandwidth of available licensed carriers and unlicensed carriers exceeds the system working bandwidth.

Usually, if there are neighboring cells with different frequencies or other RATs using different frequencies in this cell, the cell will configure measurement gaps (Measurementgap) for the UE attached to it, so that the UE periodically checks these neighboring cells with different frequencies or The RAT performs measurements and reports the measurement results, so as to assist the cell in making a handover decision for the UE to a neighboring cell or a RAT.

Referring to Fig. 1 , it is a schematic diagram of the frequency point switching structure during inter-frequency measurement in the LTE system. Inter-frequency measurement is completed during the measurement gap, and there are two cycles of 40 ms and 80 ms. The measurement gap in a radio frame consists of three parts. The actual measurement time is preceded and followed by a transceiver tuning time each. During the measurement gap, the UE cannot perform any data transmission in the cell.

At the beginning of the measurement gap, the UE first tunes the transceiver to the frequency point to be measured, which will consume some time, as shown in the grid area in Fig. 1 . After completing the first tuning of the transceiver, the UE will detect the downlink synchronization signal and the cell reference signal within the actual measurement time, and the duration of this process is shown in the hatched area. After the measurement is completed, the UE needs to tune the transceiver back to the frequency point before the start of the measurement gap, that is, the second tuning, which will also consume some time, as shown in the last grid area in Fig. 1 . After the tuning time of the transceiver at the beginning of the gap, the measurement gap is switched to another channel, and at the end of the gap, the tuning time of the transceiver is switched back to the original channel.

In order to avoid that all UEs in the cell are in the measurement gap at the same time, resulting in no UE in the cell being able to perform data transmission, resulting in waste of system resources, different gap offsets (gapOffset) are usually configured for different UEs. When a UE cannot perform data transmission in the measurement gap, there are other UEs not in the measurement gap that can perform data transmission, thereby avoiding waste of system resources.

In LTE-U, when a certain channel can no longer be used, the eNB and UE need to withdraw from the use of the channel as soon as possible and switch to another channel. Obviously, this requires that the channel switching operations of the eNB and the UE be completed within the same period of time as much as possible.

If the existing measurement gap mechanism is used, it is necessary to configure the measurement gaps of all UEs to overlap as much as possible. This contradicts the policy of configuring different gapOffsets for different UEs to avoid waste of system resources. Therefore, the existing periodic measurement gap is not suitable for LTE-U equipment to complete channel switching.

Contents of the invention

An embodiment of the present invention proposes a method for channel switching, which can complete channel switching in an LTE-U device.

The technical scheme of the embodiment of the present invention is as follows:

A method for channel switching, the method comprising:

The base station eNB triggers an aperiodic measurement gap in a radio frame;

In the aperiodic measurement gap, at the start of the transceiver tuning time, the eNB and the user UE switch the frequency of the interfered carrier to the new frequency indicated by the eNB;

From the end of the transceiver tuning time to the end of the aperiodic measurement gap, the eNB continues to transmit the signal of the interfered carrier on the new frequency point, and the UE monitors on the channel corresponding to the new frequency point.

The eNB triggering an aperiodic measurement gap in a radio frame includes:

The eNB notifies the UE of the start time and new frequency point of the aperiodic measurement gap through system information broadcast, and triggers the aperiodic measurement gap in the radio frame;

The UE includes all UEs in a cell covered by LTE-U.

The eNB triggering an aperiodic measurement gap in a radio frame includes:

The eNB notifies the UE of the start time and new frequency point of the aperiodic measurement gap through RRC dedicated signaling, and triggers the aperiodic measurement gap in the radio frame;

The UE includes a designated UE.

The eNB triggering an aperiodic measurement gap in a radio frame includes:

The eNB pre-configures the start time of the aperiodic measurement gap and the new frequency point to the UE, and triggers the aperiodic measurement gap in the radio frame by activating the MAC control unit of the medium access control layer;

The UEs include all UEs or specified UEs in a cell covered by LTE-U.

The eNB triggering an aperiodic measurement gap in a radio frame includes:

The eNB pre-configures the start time of the aperiodic measurement gap and the new frequency point to the UE, and triggers the aperiodic measurement gap in the radio frame through the extended downlink control information DCI signaling;

The UEs include all UEs or specified UEs in a cell covered by LTE-U.

The extended DCI signaling includes a modulation and coding scheme field and a HARQ progress number field, and the modulation and coding scheme field and the HARQ progress number field are used to index to a new frequency point.

The start time of the transceiver tuning time is the start time of the aperiodic measurement gap.

It can be seen from the above technical solutions that in the embodiment of the present invention, considering the aperiodicity of the measurement gap, the eNB triggers the aperiodic measurement gap in the radio frame; in the aperiodic measurement gap, the transceiver tuning time starts At this time, the eNB and UE switch the frequency of the disturbed carrier to the new frequency indicated by the eNB; from the end of the transceiver tuning time to the end of the aperiodic measurement gap, the eNB continues to transmit the disturbed carrier on the new frequency signal, the UE performs detection on the channel corresponding to the new frequency point. Since the new frequency point used by the UE corresponds to the license-free spectrum, there is no need to switch back to the original frequency point, and the frequency points used by different UEs will not overlap, so it can be successfully completed in the LTE-U device Channel switching.

Description of drawings

FIG. 1 is a schematic diagram of a frequency point switching structure when a UE performs inter-frequency measurement in an LTE system;

FIG. 2 is a schematic diagram of a frequency point handover structure when a UE performs inter-frequency measurement in an LTE-U system;

FIG. 3 is a schematic flow chart of a method for channel switching;

Fig. 4 is a schematic diagram of the format of the activated MAC control unit.

detailed description

In order to make the object, technical solution and advantages of the present invention more clearly, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

In the embodiment of the present invention, an aperiodic measurement gap is introduced into the LTE-U system, and the working channel switching of the UE is completed within the aperiodic measurement gap. Since the new frequency point used by UE corresponds to the license-free spectrum, there is no need to switch back to the original frequency point, and the frequency points used by different UEs will not overlap, so it can be done in LTE-U equipment Channel switching.

The aperiodic measurement gap is shown in Figure 2. Different from the existing periodic measurement gap, the aperiodic measurement gap only needs to reserve the time for the transceiver to tune at the frequency point in the initial stage. Since another frequency point is an unlicensed spectrum, the aperiodic measurement gap There is no need to reserve the tuning time of the transceiver in the end phase. In the aperiodic measurement gap, the monitoring is performed after the UE completes the transceiver tuning, and these operations are the same as the operations in the existing periodic measurement gap. In addition, the start time of the aperiodic measurement gap may be before the start time of the transceiver tuning time; the start time of the aperiodic measurement gap may coincide with the start time of the transceiver tuning time. When the start time of the aperiodic measurement gap coincides with the start time of the transceiver tuning time, since there is no time interval between the start time of the aperiodic measurement gap and the start time of the transceiver tuning time, the time can be effectively used Gap resources.

LTE-U devices can use carriers in the license-free frequency band in addition to the carrier in the licensed frequency band. However, the license-free carrier cannot exist independently and needs to be used in conjunction with the licensed carrier. The license-free carrier is introduced by using the carrier aggregation technology, the licensed carrier is used as the primary carrier, and the license-free carrier is used as the secondary carrier.

When the eNB judges through the existing technology that the secondary carrier on a certain unlicensed frequency band aggregated by the UE is unavailable due to interference from radar or other devices, the eNB decides to trigger an aperiodic measurement gap to switch the carrier on the unlicensed frequency band at a specified time for another frequency point.

Referring to accompanying drawing 3 is a schematic flow chart of the method for channel switching, which specifically includes the following steps:

301. The eNB triggers an aperiodic measurement gap in a radio frame.

The eNB triggers the aperiodic measurement gap in the radio frame through any one of the following four ways.

(1) Triggered by system information

The eNB broadcasts the start time of the aperiodic measurement gap and the new frequency point to be switched through the system information, and the UE can obtain the above information after receiving the system information, so as to start the aperiodic measurement gap at the specified time and switch the frequency point to the new frequency point frequency point. All UEs in the LTE-U coverage cell can be switched to the new frequency point at a specified time.

(2) Triggered by RRC dedicated signaling

The eNB notifies the designated UE of the start time and new frequency point of the aperiodic measurement gap through RRC dedicated signaling. Switch to the new frequency point. It can realize that a specific UE within the coverage of an LTE-U cell can switch to a new frequency point at a specified time.

(3) Triggered by the MAC control unit

The eNB configures the frequency point of the available carrier on the license-free frequency band, that is, the new frequency point and the starting time of the aperiodic measurement gap to the UE, and introduces a new MAC control unit for activating the aperiodic measurement gap. It can realize all or specific UEs within the coverage of LTE-U base station to switch to the new frequency point at a specified time.

The format of the aperiodic measurement gap activation MAC control element is shown in Fig. 4 . Each bit corresponds to a carrier, and setting the bit to 1 means switching to the corresponding carrier in the aperiodic measurement gap. The activation process is the same as the existing secondary carrier activation/deactivation MAC control unit, except that the aperiodic measurement gap activation MAC control unit only has the function of activating the aperiodic measurement.

(4) Triggered by DCI signaling

The eNB pre-configures the frequency point of the available carrier on the license-free frequency band, that is, the new frequency point and the starting time of the aperiodic measurement gap to the UE, and the existing DCI format is extended to activate the aperiodic measurement gap. All or specific UEs within the coverage of LTE-U can be switched to the new frequency point at a specified time.

The aperiodic measurement gap is triggered by using the carrier indicator field (CIF) in the DCI format. The DCI that triggers the aperiodic measurement gap adopts the DCI1A format. When the value indicated by the CIF field received by the UE does not have a carrier index, the UE triggers an aperiodic measurement gap at a specified moment. The interfered carrier and the corresponding new frequency point for which frequency switching is to be performed are indicated by other fields in the DCI format. Modulation and coding scheme (Modulation and coding scheme) fields and HARQ process number (HARQ process number) fields may be used to indicate respectively.

That is, the eNB configures the information of at least one new frequency point and the start and end times of the aperiodic measurement gap to the UE, and then performs indexing through the modulation and coding scheme field and the HARQ process number field in the DCI to determine the new frequency point.

302. In the aperiodic measurement gap, at the starting moment of the transceiver tuning time, the eNB and the UE switch the frequency point of the interfered carrier to the new frequency point indicated by the eNB.

After the aperiodic measurement period starts, the eNB and UE will also switch the frequency point of the interfered carrier to the new frequency point indicated by the eNB within the transceiver tuning time to complete the tuning on the new frequency point.

303. From the end of the transceiver tuning time to the end of the aperiodic measurement gap, the eNB continues to transmit the signal of the interfered carrier on the new frequency point, and the UE monitors on the channel corresponding to the new frequency point.

The eNB performs normal cell operations after tuning, including the transmission of signals such as PSS, SSS, and CRS, that is, continues to transmit signals of the interfered carrier on the new frequency point.

After the UE completes the transceiver tuning, it starts to monitor the PSS, SSS and cell reference signal, that is, monitors on the channel corresponding to the new frequency point. These operations are the same as in existing periodic measurement gaps.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (7)

1. a method for channel switching, it is characterized in that, described method comprises:

Base station eNB triggers measurement clearance aperiodic in radio frames;

In aperiodic measurement clearance, transceiver tuning period initial time, the frequency being disturbed carrier wave is switched on the new frequency of eNB instruction by eNB and user UE;

Transceiver tuning period finish time to aperiodic measurement clearance terminate, eNB continues to transmit and is disturbed the signal of carrier wave on described new frequency, and UE monitors on the channel that described new frequency is corresponding.

2. the method that switches of channel according to claim 1, it is characterized in that, described eNB triggers aperiodic measurement clearance and comprises in radio frames:

ENB by aperiodic measurement clearance initial time and new frequency inform UE by system information broadcast, in radio frames, trigger measurement clearance aperiodic;

Described UE comprises all UE in LTE-U coverage cell.

3. the method that switches of channel according to claim 1, it is characterized in that, described eNB triggers aperiodic measurement clearance and comprises in radio frames:

ENB by RRC dedicated signaling by aperiodic measurement clearance initial time and new frequency inform UE, in radio frames, trigger measurement clearance aperiodic;

Described UE comprises the UE specified.

4. the method that switches of channel according to claim 1, it is characterized in that, described eNB triggers aperiodic measurement clearance and comprises in radio frames:

ENB by aperiodic measurement clearance initial time and new frequency pre-configured give UE, in radio frames, trigger measurement clearance aperiodic by active medium MAC layer MAC Control Element;

The UE that described UE comprises all UE in LTE-U coverage cell or specifies.

5. the method that switches of channel according to claim 1, it is characterized in that, described eNB triggers aperiodic measurement clearance and comprises in radio frames:

ENB by aperiodic measurement clearance initial time and new frequency pre-configured give UE, by expansion after Downlink Control Information DCI signaling in radio frames, trigger measurement clearance aperiodic;

The UE that described UE comprises all UE in LTE-U coverage cell or specifies.

6. the method for channel switching according to claim 5, is characterized in that, the DCI signaling after described expansion comprises modulating-coding mechanism territory and the HARQ number of carrying out territory, and described modulating-coding mechanism territory and the described HARQ number of carrying out territory are for being indexed to new frequency.

7. the method for channel switching according to claim 1, it is characterized in that, described transceiver tuning period initial time is measurement clearance initial time aperiodic.