TWI682676B - Method for handover based on uplink reference signal and wireless communication system - Google Patents

Abstract

The disclosure provides a method for handover based on uplink reference signal and a wireless communication system. The method includes: receiving, by a source eNB (SeNB) and a target eNB (TeNB), an uplink reference signal (ULRS) from user equipment (UE); determining, by the SeNB and the TeNB, whether a handover triggering event occurs based on the ULRS; in response to the handover triggering event occurs, sending, by the SeNB, a handover command to the UE to control the UE to handover to the TeNB.

Description

Handover method and wireless communication system based on uplink reference signal

The invention relates to a mobile phone changing system and a wireless communication system, and particularly relates to a handover method and a wireless communication system based on an uplink reference signal.

Please refer to FIG. 1, which is a schematic diagram of a conventional mobile phone change system. As shown in FIG. 1, in the existing communication system, when the base station and the user equipment (UE) are in a connected state, the system may adopt a downlink reference signal (downlink reference signal) as the UE moves signal, DLRS). Specifically, in this mechanism, the UE receives and measures the downlink reference signals from the source base station (Source eNN, SeNB) and the target base station (Target eNB, TeNB).

If a trigger event occurs that meets a certain condition (for example, the signal quality of TeNB is higher than the signal quality of SeNB exceeds a threshold), and this condition is maintained for a trigger time (time-to-trigger, TTT)), the UE may send a measurement report ( measurement report) to the SeNB, so that the SeNB can decide whether the UE should perform handover. If the SeNB decides to change hands, the SeNB sends a handover request (HO request) to the TeNB, and after the TeNB receives the handover request, it can determine whether to allow the handover according to its own available resources. If the TeNB approves the handover, it can reply the HO response to the SeNB, and attach the relevant handover information required during the handover process (eg RACH available channel). After the SeNB receives the HO response, it can attach the handover information to the HO command and transmit it to the UE.

The flow from when the SeNB receives the measurement report until the SeNB sends the HO command can be defined as HO preparation. After the UE receives the HO command, it synchronizes the TeNB and executes the RACH procedure. After the UE connects to the TeNB, the TeNB will allocate the available uplink (UL) resources to the UE through the UL allocation procedure, and the UE will reply HO complete to inform the TeNB that the handover is completed.

However, since it is necessary to wait for the TTT before sending the measurement report, this not only delays the time point at which the HO is completed, it is also more likely to reduce the probability of HO's success because the signal quality of the SeNB has excessively deteriorated.

In view of this, the present invention proposes a handover mechanism and wireless communication system based on uplink reference signal (ULRS), which can be used to solve the above technical problems.

The present invention provides a handover method based on an uplink reference signal, which is suitable for a wireless communication system including a user equipment, a source base station, and a target base station. The method includes: receiving by the source base station and the target base station An uplink reference signal from the user equipment, where the uplink reference signal is exclusive to the user equipment; the source base station and the target base station determine whether a handover trigger event occurs based on the uplink reference signal; and in response to the handover trigger event, The source base station sends a handover command to the user equipment to control the user equipment to handover to the target base station.

The invention provides a wireless communication system, including user equipment, a source base station and a target base station. The user equipment sends an uplink reference signal, where the uplink reference signal is dedicated to the user equipment. The source base station serves the user equipment and receives the uplink reference signal from the user equipment. The target base station connects to the source base station and receives the uplink reference signal from the user equipment. The source base station and the target base station determine whether a handover trigger event occurs based on the uplink reference signal. In response to the handover triggering event, the source base station sends a handover command to the user equipment to control the user equipment to handover to the target base station.

Based on the above, the handover method based on the uplink reference signal and the wireless communication system proposed by the present invention allow the UE to send dedicated ULRS to SeNB and TeNB, so that SeNB and TeNB can measure and exchange ULRS signal strength in real time. When a handover triggering event occurs, SeNB and TeNB can make HO preparation earlier, which can improve the efficiency and probability of success of UE handover to TeNB.

In order to make the above-mentioned features and advantages of the present invention more obvious and understandable, the embodiments are specifically described below in conjunction with the accompanying drawings for detailed description as follows.

The enhanced node "eNodeB" or "eNB" in the present invention may be, for example, a base station (BS), a node-B, an advanced base station (ABS), a base transceiver system (BTS), an access point , Home base station (home base station), relay station (relay station), scatterer (scatterer), repeater (repeater), intermediate node, intermediary and/or satellite-based communication base station and the like.

The term “user equipment” (UE) in the present invention may be, for example, a mobile station, advanced mobile station (AMS), server, client, desktop computer, laptop computer, network computer, Workstation, personal digital assistant (PDA), tablet personal computer (PC), scanner, telephone device, pager, camera, TV, handheld video game device, music device, wireless sensor and their analog. In some applications, the UE may be a fixed computer device operating in a mobile environment such as a bus, train, airplane, ship, automobile, and the like.

Please refer to FIG. 2, which is a schematic diagram of a wireless communication system according to an embodiment of the present invention. As shown in FIG. 2, the wireless communication system 200 includes a UE 21, a SeNB 22, and a TeNB 23, where the SeNB 22 serves the UE 21, and the TeNB 23 can be connected to the SeNB 22 through a backhaul network.

According to the LTE communication standard, the wireless communication system includes at least one eNB, such as SeNB 22 and TeNB 23. Each eNB communicates with at least one UE (eg, UE 21). Each UE contains, for example, at least one transceiver circuit, an antenna, analog-to-digital (A/D) and digital-to-analog (D/C) converters, and a processing circuit. The transceiver circuit can wirelessly transmit uplink signals and/or receive downlink signals. The transceiver circuit can also perform operations such as low noise amplification, impedance matching, frequency mixing, up or down frequency conversion, filtering, amplification, and the like. The transceiver circuit also contains an antenna unit. The analog digital and digital analog converters are configured to convert the analog signal format to a digital signal format during downlink signal processing and convert the digital signal format to an analog signal format during uplink signal processing. The processing circuit is configured to process digital signals and execute the program of the proposed method for data transmission according to an exemplary embodiment of the present invention. In addition, the processing circuit may include a memory circuit for storing data or recording the configuration assigned by the eNB. The eNB contains similar components, including transceiver units, antennas, and analog-to-digital (A/D) and digital-to-analog (D/C) converters, which makes the converted digital signal from Its processing circuit processes and uses a memory circuit to implement the method according to the exemplary embodiment of the present invention.

Please refer to FIG. 3, which is a flowchart of a handover method of an uplink reference signal according to an embodiment of the invention. The method of this embodiment can be performed by the wireless communication system 200 shown. The details of each step in FIG. 3 will be described below with the components shown in FIG. 2.

First, in step S310, SeNB 22 and TeNB 23 may receive ULRS S1 from UE 21, and ULRS S1 may be dedicated to UE 21. In an embodiment, SeNB 22 may allocate a unique communication resource to UE 21, so that when SeNB 22 and TeNB 23 receive ULRS S1 through the unique communication resource, they can recognize that ULRS S1 is from UE 21 However, the present invention may not be limited to this.

Thereafter, in step S320, SeNB 22 and TeNB 23 may determine whether a handover trigger event occurs based on ULRS S1. In an embodiment, after the SeNB 22 receives the ULRS from the UE 21, the SeNB 22 may measure the first signal strength of the ULRS and send the first signal strength to the TeNB 23. Similarly, after the TeNB 23 receives the ULRS from the UE 21, the TeNB 23 may measure the second signal strength of this ULRS and send the second signal strength to the SeNB 22. In short, after measuring the signal strength of the ULRS of the UE 21 separately, the SeNB 22 and the TeNB 23 can inform the other party of the measured signal strength through the back-end network (such as the Xn interface). In an embodiment, if the second signal strength is higher than the first signal strength by a preset threshold, the SeNB 22 and the TeNB 23 can determine that a handover trigger event occurs, but the present invention is not limited thereto.

Thereafter, in step S330, in response to the occurrence of a handover trigger event, the SeNB 22 may send a handover command to the UE 21 to control the UE 21 to handover to the TeNB 23. In an embodiment, assuming that SeNB 22 and TeNB 23 determine that a handover trigger event occurs at the first time point, SeNB 22 and TeNB 23 may start a pre-preparation handover operation at the second time point, A time difference between the second time point and the first time point is less than the trigger time (ie, TTT).

In one embodiment, the above-mentioned preparation for handover operation may include the SeNB 22 sending the HO request to the TeNB 23, and the TeNB 23 responding to the HO request and returning the HO response to the SeNB 22. Relevant details can refer to the description of FIG. 1 and will not be repeated here.

In this way, the UE 21 can switch to the TeNB 23 earlier because there is no need to generate another measurement report. In order to highlight the advantageous effects of the present invention, the following is supplemented by FIG. 4 for further explanation.

Please refer to FIG. 4, which is a comparison diagram of the conventional method and the method of the present invention. In FIG. 4, the upper half is a mobile phone swapping mechanism performed by a conventional method, and the lower half is a mobile phone swapping mechanism based on the method proposed by the present invention.

As shown in FIG. 4, in the conventional method, after a handover trigger event occurs, it is necessary to wait for TTT before sending a measurement report, and then start HO preparation. However, in the method of the present invention, since the SeNB and the TeNB do not need to wait for the measurement report from the UE, they can immediately start at the second time point T2 after judging that the handover triggering event (occurring at the first time point T1) occurs. HO ready. It can be seen from FIG. 4 that since the time difference between the second time point T2 and the first time point T1 is less than TTT, the mobile phone switching mechanism of the UE can be completed earlier, thereby increasing the efficiency of the switching.

In addition, as can be seen from FIG. 4, in the conventional method, the first signal strength when performing HO is already too low, so it will affect the success probability of HO. In addition, the measurement report transmitted by the UE may be lost. However, in the method proposed by the present invention, the first signal strength when performing HO is high, and the measurement report does not need to be considered, so a high probability of HO success can be achieved.

In addition, the embodiments of the present invention also propose a switching mechanism (hereinafter referred to as a first switching mechanism) that allows the UE to switch to the DLRS as the basis for performing the handover operation in a timely manner, so as to save the communication resources consumed by the ULRS. In summary, in different embodiments, the above-mentioned first handover mechanism may include: the UE or the SeNB determines whether a first reference signal handover event occurs; and in response to the occurrence of the first reference signal handover event, the SeNB may control the UE to hand over to The DLRS from the SeNB is used as the basis for performing the handover operation. The following will be supplemented by FIG. 5A and FIG. 5B for further explanation.

Please refer to FIG. 5A, which is a schematic diagram illustrating that the first handover mechanism is dominated by the UE according to an embodiment of the present invention. As shown in FIG. 5A, the UE 21 may (periodically) transmit ULRS to the SeNB 22. In this embodiment, the UE 21 may store its own hand-off record. In this case, the UE 21 can determine whether the UE 21 will not perform the handover operation within a preset time according to the handover record. If yes, the UE 21 may determine that a first reference signal switching event has occurred, and accordingly send a first reference signal switching request to the SeNB 22 to request the SeNB 22 to control the UE 21 to switch to DLRS as a basis for performing a handover operation. That is, if the UE 21 determines that it will not perform a handover operation in a short time, it may request the SeNB 22 to control the UE 21 to switch to use DLRS as the basis for performing the handover operation, thereby saving communication resources for transmitting ULRS.

Accordingly, the SeNB 22 may send the first control signal to the UE 21 to notify the UE 21 that it is ready to receive DLRS. In an embodiment, if the UE 21 is in the stage of accumulating TTT, the SeNB 22 may append the current TTT value to the first control signal. In addition, SeNB 22 can also release the communication resources corresponding to ULRS.

After the UE 21 receives the first control signal, it may respond to the first control signal and send back the first confirmation message to the SeNB 22. Then, SeNB 22 may (periodically) send DLRS in response to the first acknowledgement message.

Please refer to FIG. 5B, which is a schematic diagram illustrating that the first handover mechanism is dominated by SeNB according to an embodiment of the present invention. As shown in FIG. 5B, the UE 21 may (periodically) transmit ULRS to the SeNB 22. Next, the SeNB 22 may determine whether the handover frequency of the UE 21 is lower than the frequency threshold. If so, the SeNB 22 may determine that the first reference signal switching event occurs, and accordingly control the UE 21 to switch to use DLRS as a basis for performing the handover operation. That is, after judging that the UE 21 is less frequently performing the handover operation, the SeNB 22 can correspondingly control the UE 21 to switch to the DLRS as a basis for performing the handover operation, thereby saving communication resources for transmitting ULRS.

Accordingly, the SeNB 22 may send the first control signal to the UE 21 to notify the UE 21 that it is ready to receive DLRS. In an embodiment, if the UE 21 is in the stage of accumulating TTT, the SeNB 22 may append the current TTT value to the first control signal. In addition, SeNB 22 can also release the communication resources corresponding to ULRS.

After the UE 21 receives the first control signal, it may respond to the first control signal and send back the first confirmation message to the SeNB 22. Then, SeNB 22 may (periodically) send DLRS in response to the first acknowledgement message. In an embodiment, if the SeNB 22 does not receive the first acknowledgement message after waiting for a period of time, the SeNB 22 may send the first control signal to the UE 21 again, but the present invention is not limited thereto.

In addition, the embodiments of the present invention also provide a switching mechanism (hereinafter referred to as a second switching mechanism) that allows UEs to switch to ULRS as a basis for performing handover operations in a timely manner, so as to allow UEs with higher mobility or more frequent handovers Dry hands with better efficiency. In summary, in different embodiments, the second handover mechanism may include: the SeNB sends a DLRS to the UE, where the DLRS is the basis for the UE to perform a handover operation; the UE or the SeNB determines whether the second reference signal handover occurs Event; and in response to the occurrence of the second reference signal switching event, the SeNB evaluates whether the UE is allowed to switch to use ULRS as the basis for performing the handover operation; if so, the UE is controlled to switch to use ULRS as the basis for performing the handover operation. The following will be supplemented by FIG. 6A and FIG. 6B for further explanation.

Please refer to FIG. 6A, which is a schematic diagram illustrating that the second handover mechanism is dominated by the UE according to an embodiment of the present invention. As shown in FIG. 6A, SeNB 22 may (periodically) send DLRS to UE 21. In this embodiment, the UE 21 can determine whether a rate of decrease in a signal quality of the DLRS is higher than the first threshold or continuously lower than the second threshold for a preset time. If yes, the UE 21 may determine that a second reference signal switching event has occurred, and send a second reference signal switching request to the SeNB 22 to request the SeNB 22 to control the UE 21 to switch to ULRS as the basis for performing the handover operation. In different embodiments, the signal quality of the DLRS may be poor due to the high-speed movement of the UE 21, so the UE 21 may request the SeNB 22 to switch to ULRS after judging that the second reference signal switching event occurs As a basis for performing a hand-over operation, in order to achieve a better hand-over operation efficiency and success rate.

Accordingly, the SeNB 22 may send a second control signal to the UE 21, where the second control signal includes the communication resource corresponding to the ULRS. That is, the SeNB 22 may arrange communication resources dedicated to transmitting ULRS for the UE 21. In an embodiment, after the SeNB 22 receives the second reference signal switching request, the SeNB 22 may evaluate whether the number of available ULRSs is sufficient for the UE 21 to switch to use ULRSs as the basis for performing the handover operation. If there are still ULRS resources, SeNB 22 may send a second control signal to UE 21, otherwise SeNB 22 may send a rejection signal to UE 21 to inform UE 21 that ULRS cannot be used, but the invention may not be limited to this.

After that, the UE 21 may respond to the second control signal and return the first response to the SeNB 22, and then (periodically) transmit the ULRS. In an embodiment, the first response may include the current TTT record of the UE 21. Accordingly, SeNB 22 may (periodically) receive ULRS in response to the first response.

Please refer to FIG. 6B, which is a schematic diagram of the second handover mechanism dominated by SeNB according to an embodiment of the present invention. As shown in FIG. 6A, SeNB 22 may (periodically) send DLRS to UE 21. SeNB 22 determines whether a handover frequency of UE 21 is higher than a frequency threshold. If so, the SeNB 22 can determine that the second reference signal switching event occurs, and control the UE 21 to switch to ULRS as the basis for performing the handover operation. That is, after judging that UE 21 frequently performs handover operations due to high mobility and other reasons, SeNB 22 can switch UE 21 to use ULRS as a basis for performing handover operations, so as to achieve better handover operation efficiency and success rate.

After that, the SeNB 22 may send a second control signal to the UE 21, where the second control signal includes the communication resource corresponding to the ULRS. That is, the SeNB 22 may arrange communication resources dedicated to transmitting ULRS for the UE 21. Then, the UE 21 may return the first response to the SeNB 22 in response to the second control signal, and then (periodically) transmit the ULRS. In an embodiment, the first response may include the current TTT record of the UE 21. In another embodiment, if the SeNB 22 does not receive the first response from the UE 21 after waiting for a period of time, the SeNB 22 may send the second control signal to the UE 21 again, but the present invention is not limited thereto. Accordingly, SeNB 22 may (periodically) receive ULRS in response to the first response.

In some embodiments, due to the limited communication resources available for transmitting ULRS, the present invention further proposes a screening mechanism that can be used to find one or more UEs that are more suitable for performing handover operations based on ULRS from multiple UEs By.

Please refer to FIG. 7, which is a flowchart of selecting user equipment using ULRS according to an embodiment of the present invention. In this embodiment, it is assumed that the SeNB serves U first UEs, and these first UEs all use corresponding DLRSs as the basis for performing the handover operation.

In step S710, the SeNB may distinguish the first UE into R second UEs and (U-R) third UEs, and control the second UE to individually switch to use the corresponding ULRS as the basis for performing the handover operation. In this embodiment, the R second UEs may be randomly selected by the SeNB from the U first UEs, but the present invention may not be limited to this.

In step S720, the SeNB may measure the signal strength of the ULRS corresponding to each second UE in the screening period. Furthermore, in step S730, the SeNB may find N fourth UEs from the second UE, where the signal strength of the first ULRS corresponding to each fourth UE is higher than a strength threshold. In one embodiment, the SeNB can be regarded as finding the N UEs with better signal strength from the second UE as the fourth UE, that is, finding the N UEs from the second UE that are less likely to perform handover operations as the Fourth UE, but the invention may not be limited to this.

In step S740, the SeNB may control the fourth UE to individually switch to use the corresponding DLRS as a basis for performing the handover operation. That is, for N fourth UEs that are less likely to perform a handover operation, the SeNB can accordingly control each fourth UE to switch to use DLRS as a basis for performing the handover operation, thereby saving communication resources for transmitting ULRS .

In step S750, the SeNB may select n fifth UEs from the third UEs, and control the fifth UEs to individually switch to use the corresponding ULRS as the basis for performing the handover operation. That is, the SeNB may select n out of (U-R) third UEs that still use DLRS as the fifth UE, and let each fifth UE switch to use the corresponding ULRS individually as a basis for performing the handover operation.

In step S760, the SeNB may determine whether the second reference signal switching request is received. If yes, step S780 is continued, otherwise, step S770 is continued. As described in the previous embodiment, the second reference signal switching request is sent by a UE (hereinafter referred to as the sixth UE) to the SeNB to request the SeNB to control the switching of the sixth UE to ULRS as the execution after judging the occurrence of the second reference signal switching event. The basis for changing hands.

In step S780, the SeNB may evaluate whether to allow the sixth UE to switch to use the corresponding ULRS as a basis for performing the handover operation. If yes, step S790 is continued, otherwise, step S770 is continued. In this embodiment, the SeNB can determine whether ULRS communication resources are available, and if so, it can determine that the sixth UE is allowed to switch to use the corresponding ULRS as the basis for performing the handover operation, and then control the sixth UE to switch in step S790 To use the corresponding ULRS as the basis for performing the handover operation (for example, to allocate the corresponding ULRS communication resources, etc.).

In step S770, the SeNB may determine whether the screening period is over. If yes, it can return to step S720, otherwise, it can return to step S760. In different embodiments, the length of the screening period can be determined by the designer according to requirements, and the invention is not limited.

In summary, the handover method and wireless communication system based on the uplink reference signal proposed by the present invention allow the UE to send dedicated ULRS to SeNB and TeNB, so that SeNB and TeNB can measure and exchange ULRS signal strength in real time. When a handover triggering event occurs, SeNB and TeNB can make HO preparation earlier, which can improve the efficiency and probability of success of UE handover to TeNB.

In addition, the present invention also proposes a mechanism to allow the UE to switch to ULRS/DLRS as the basis for performing the handover operation in a timely manner. In this way, UEs that change hands more frequently can be switched to use ULRS as a basis for performing handover operations, thereby improving the efficiency and probability of success of UE handovers. At the same time, UEs that change hands less frequently can be switched to use DLRS as the basis for performing handover operations, thereby saving communication resources for transmitting ULRS.

In addition, the present invention also proposes a screening mechanism that can be used to find one or more UEs that are more suitable for performing handover operations based on ULRS from multiple UEs. In this way, the communication resources of ULRS can be used more efficiently.

Although the present invention has been disclosed as above with examples, it is not intended to limit the present invention. Any person with ordinary knowledge in the technical field can make some changes and modifications without departing from the spirit and scope of the present invention. The scope of protection of the present invention shall be subject to the scope defined in the appended patent application.

200‧‧‧Wireless communication system

21‧‧‧UE

22‧‧‧SeNB

23‧‧‧TeNB

S1‧‧‧ULRS

S310~S330, S710~S790‧‧‧Step

FIG. 1 is a schematic diagram of a conventional mobile phone replacement mechanism. 2 is a schematic diagram of a wireless communication system according to an embodiment of the invention. FIG. 3 is a flowchart of a handover method of an uplink reference signal according to an embodiment of the invention. FIG. 4 is a comparison diagram of the conventional method and the method of the present invention. FIG. 5A is a schematic diagram illustrating that the first handover mechanism is dominated by the UE according to an embodiment of the present invention. FIG. 5B is a schematic diagram illustrating that the first handover mechanism is dominated by SeNB according to an embodiment of the present invention. FIG. 6A is a schematic diagram illustrating that the second handover mechanism is dominated by the UE according to an embodiment of the present invention. FIG. 6B is a schematic diagram illustrating that the second handover mechanism is dominated by SeNB according to an embodiment of the present invention. FIG. 7 is a flowchart of selecting user equipment using ULRS according to an embodiment of the invention.

S310~S330‧‧‧Step

Claims (14)

A handover method based on an uplink reference signal is suitable for a wireless communication system including a user equipment, a source base station and a target base station. The method includes: receiving from the source base station and the target base station An uplink reference signal of the user equipment, wherein the uplink reference signal is dedicated to the user equipment; the source base station and the target base station determine whether a handoff trigger event occurs based on the uplink reference signal; and react to the occurrence In the handover triggering event, the source base station sends a handover command to the user equipment to control the user equipment to handover to the target base station; where the source base station and the target base station receive the Before the step of the uplink reference signal of the user equipment, the method further includes: serving U first user equipments by the source base station, wherein the first user equipments individually use corresponding downlink reference signals as The basis for whether to perform a handover operation; the source base station distinguishes these first user equipments into R second user equipments and (UR) third user equipments; the source base station controls these The second user equipment is individually switched to use a corresponding first uplink reference signal as a basis for performing the handover operation; in a screening period, the source base station measures the first corresponding to each second user equipment A signal strength of an uplink reference signal; The source base station finds N fourth user equipments from the second user equipments, wherein the signal strength of the first uplink reference signal corresponding to each fourth user equipment is higher than a strength threshold The source base station controls the fourth user equipment to individually switch to use the corresponding downlink reference signal as a basis for performing the handover operation; and the source base station selects n from the third user equipment A fifth user equipment, and control the fifth user equipment to individually switch to use the corresponding first uplink reference signal as a basis for performing the handover operation. The method according to item 1 of the patent application scope, wherein the step of the source base station and the target base station determining whether the handover trigger event occurs based on the uplink reference signal includes: the source base station measuring the uplink reference signal A first signal strength and send the first signal strength to the target base station; the target base station measures a second signal strength of the uplink reference signal and sends the second signal strength to the source base station ; And if the second signal strength is higher than the first signal strength by a preset threshold, the source base station and the target base station determine that the handover triggering event occurs. The method as described in item 2 of the patent application scope, wherein the handoff trigger event occurs at a first point in time, and after the source base station and the target base station determine that the handoff trigger event occurs, the method It also includes: The source base station and the target base station start a pre-handover operation at a second time point, where a time difference between the second time point and the first time point is less than a trigger time. The method as described in item 3 of the patent application scope, wherein the step of performing the preparatory handover operation in advance includes: sending a handover request from the source base station to the target base station; the target base station reacting to the handover Request and return a handover response to the source base station. The method as described in item 1 of the patent application scope further includes: determining whether a first reference signal switching event occurs by the user equipment or the source base station; and responding to the occurrence of the first reference signal switching event by the The source base station controls the user equipment to switch to the next reference signal from the source base station as a basis for performing a handover operation. The method as described in item 5 of the patent application scope, wherein the user equipment stores a handover record, and the step of determining whether the first reference signal switching event occurs by the user equipment includes: the user equipment according to the The handover record determines whether the user equipment will not perform the handover operation within a preset time; if so, the user equipment sends a first reference signal switching request to the source base station to request the source base station Controlling the user equipment to switch to use the downlink reference signal as a basis for performing the handover operation. The method according to item 5 of the patent application scope, wherein the step of determining whether the first reference signal switching event occurs by the source base station includes: determining whether a handover frequency of the user equipment is lower than the source base station A frequency threshold; if so, the source base station controls the user equipment to switch to the downlink reference signal as a basis for performing the handover operation. The method as described in item 5 of the patent application scope, wherein the step of controlling the user equipment switching by the source base station to use the downlink reference signal from the source base station as a basis for performing the handover operation includes: The source base station sends a first control signal to the user equipment to notify the user equipment that it is ready to receive the downlink reference signal; the source base station releases a communication resource corresponding to the uplink reference signal; the user equipment responds Return a first acknowledgement message to the source base station at the first control signal; and send the downlink reference signal by the source base station in response to the first acknowledgement message. The method according to item 1 of the patent application scope, wherein before the step of receiving the uplink reference signal from the user equipment by the source base station and the target base station, the method further includes: the source base station Sending a downlink reference signal to the user equipment, wherein the downlink reference signal is the basis for the user equipment to perform a hand-over operation; The user equipment or the source base station determines whether a second reference signal switching event occurs; and in response to the second reference signal switching event, the source base station evaluates whether the user equipment is allowed to switch to the uplink The reference signal is used as a basis for performing the handover operation; if so, the user equipment is controlled to switch to use the uplink reference signal as the basis for performing the handover operation. The method as described in item 9 of the patent application range, wherein the step of determining by the user equipment whether the second reference signal switching event occurs includes: determining, by the user equipment, a rate of degradation of a signal quality of the downlink reference signal Whether it is higher than a first threshold or continuously lower than a second threshold for a preset time; if so, the user equipment sends a second reference signal switching request to the source base station to request the source The base station controls the user equipment to switch to use the uplink reference signal as a basis for performing the handover operation. The method as described in item 9 of the patent application scope, wherein the step of determining by the source base station whether the second reference signal switching event occurs includes: determining by the source base station whether a handover frequency of the user equipment is higher than A frequency threshold; if so, the source base station controls the user equipment to switch to use the uplink reference signal as a basis for performing the handover operation. The method as described in item 9 of the patent application scope, wherein the step of controlling the user equipment to switch to use the uplink reference signal as the basis for performing the handover operation by the source base station includes: sending a first Two control signals to the user equipment, wherein the second control signal includes a communication resource corresponding to the uplink reference signal; the user equipment returns a first response to the source base station in response to the second control signal; And the source base station receives the uplink reference signal in response to the first response. The method as described in item 1 of the patent application scope further includes: in response to receiving a reference signal switching request from a sixth user equipment, the source base station assesses whether the sixth user equipment is allowed to switch to correspond The first uplink reference signal as the basis for performing the handover operation; and if it is, the source base station controls the sixth user equipment to switch to use the corresponding first uplink reference signal as the basis for performing the handover operation . A wireless communication system includes: a user equipment that sends an uplink reference signal, wherein the uplink reference signal is dedicated to the user equipment; a source base station that serves the user equipment and receives the user equipment from the user equipment The uplink reference signal; a target base station connected to the source base station and receiving the uplink reference signal from the user equipment, Wherein, the source base station and the target base station determine whether a handover trigger event occurs based on the uplink reference signal; and in response to the handover trigger event, the source base station sends a handover command to the user equipment, To control the user equipment to switch to the target base station, wherein before the source base station receives the uplink reference signal from the user equipment, the source base station is further configured to: serve U first user equipment , Where the first user equipment individually uses the corresponding next-line reference signal as a basis for whether to perform a hand-over operation; the first user equipment is divided into R second user equipment and (UR) third Three user equipments; controlling the second user equipments to individually switch to use a corresponding first uplink reference signal as a basis for performing the handover operation; during a screening period, measuring corresponding to each second user equipment A signal strength of the first uplink reference signal; find N fourth user equipments from the second user equipments, wherein the signal of the first uplink reference signal corresponding to each fourth user equipments The intensity is higher than an intensity threshold; controlling the fourth user equipment to individually switch to use the corresponding downlink reference signal as a basis for performing the handover operation; and selecting n fifths from the third user equipment User equipment, and control the fifth user equipment to switch to use the corresponding first uplink reference signal as a basis for performing the handover operation.

Images