Cell selection method and user equipment

A cell selection method and user equipment (UE) are provided. The cell selection method is applied to the UE. The cell selection method includes the steps of obtaining a candidate cell group; selecting a first candidate cell sub-group from the candidate cell group according to the communication ability supported by each candidate cell of the candidate cell group; and selecting a camping cell of the UE from the first candidate cell sub-group.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority of CN Provisional Patent Application No. 201810705840.6, filed on Jul. 2, 2018, the entirety of which is incorporated by reference herein.

BACKGROUND OF THE INVENTION

Field of the Invention

The invention generally relates to a cell selection technology, and more particularly, to the cell selection technology for selecting the camping cell according to the communication ability of the candidate cells.

Description of the Related Art

As mobile communication networks have developed in recent years, people have higher requirements for the data service provided through mobile terminals (user equipment) and there are more requirements on the throughput of a data service. Data services may comprise browsing the web, watching videos, online gaming, video calls, high-speed downloads, and so on.

With the development of mobile communication technologies, and particularly Long Term Evolution (LTE) technology (i.e. 4G technology), LTE-Advanced technology (i.e. 4G+ technology), and the 5G technology, mobile terminals can achieve faster uplink data and downlink data throughput. Therefore, user experience may be improved. In addition, some older communication technologies (e.g. 2G, 3G communication technologies) may still be used, and may still coexist with the new communication technologies (e.g. 4G, 4G+, 5G) for a while.

However, current standards do not specify that the mobile terminal can actively query the communication ability of a network. Therefore, before the mobile terminal camps on a cell, the mobile terminal does not know whether the cell can support the communication ability of the mobile terminal to allow the mobile terminal to reach high performance (i.e. the mobile terminal can know whether the communication ability of the cell matches its communication ability). As a result, the performance (e.g. the throughput of the data service) of the mobile terminal may be affected. In addition, because different network operators may have different network resources, e.g. frequency band, bandwidth, and so on, in a real network environment, even if different cells can support the same communication technology, the network resources (e.g. bandwidth) provided through the cells may be different. The difference may also affect the throughput of the mobile terminal. In addition, in the real network environment, there are some problems, such as the uneven coverage of the network signal in the network deployment, the interference between the cells, which may also affect the throughput of the data service on the mobile terminal.

In current communication standards, in camping cell selection, the mobile terminal may select a camping cell mainly according to the signal strengths of the cells. However, the mobile terminal does not further concern the factors, such as the communication abilities of the cells, the wireless communication resource which can be provided, the quality of the signal and the interference, for the data service. Therefore, in a real network environment, sometimes the signal strength of a cell is good, but the throughput of the data service is bad. Therefore, the experience of the user of a mobile terminal may be affected. Therefore, how to increase the throughput of the data service in a real network environment to improve the experience of the user of the mobile terminal is an issue which needs to be solved.

BRIEF SUMMARY OF THE INVENTION

A cell selection method and user equipment (UE) are provided to overcome the problems mentioned above.

An embodiment of the invention provides a cell selection method. The cell selection method is applied to user equipment (UE). The cell selection method comprises the steps of obtaining a candidate cell group; selecting a first candidate cell sub-group from the candidate cell group according to the communication ability supported by each candidate cell of the candidate cell group; and selecting a camping cell of the UE from the first candidate cell sub-group.

In some embodiments of the invention, the cell selection method further comprises the steps of if the first candidate cell sub-group comprises at least two candidate cells, selecting a second candidate cell sub-group from the first candidate cell sub-group according to network resource of each candidate cell of the first candidate cell sub-group; and selecting the camping cell of the UE from the second candidate cell sub-group.

In some embodiments of the invention, the cell selection method further comprises the step of if the first candidate cell sub-group comprises only one candidate cell, selecting the candidate cell of the first candidate cell sub-group to be the camping cell of the UE.

In some embodiments of the invention, the cell selection method further comprises the step of if the second candidate cell sub-group comprises at least two candidate cells, selecting the camping cell of the UE according to the signal environment parameters of each candidate cell of the second candidate cell sub-group.

In some embodiments of the invention, the cell selection method further comprises the step of if the second candidate cell sub-group comprises only one candidate cell, selecting the candidate cell of the second candidate cell sub-group to be the camping cell of the UE.

In some embodiments of the invention, the cell selection method further comprises the step of obtaining information about the communication ability supported by each candidate cell of the candidate cell group according to messages broadcast by the candidate cells and information stored by the UE.

In some embodiments of the invention, the communication abilities supported by the candidate cell comprise whether the candidate cell supports the 5G communication technology, whether the candidate cell supports the carrier aggregation (CA) technology, and whether the candidate cell supports the 256 Quadrature Amplitude Modulation (QAM) encoding technology, but the invention should not be limited thereto, wherein different communication abilities have different priorities. In some embodiments of the invention, the network resources of the candidate cell comprises the bandwidth and the length of the time slot, but the invention should not be limited thereto, wherein different network resources have different priorities. In some embodiments of the invention, the signal environment parameters of the candidate cell comprise the signal strength of the candidate cell and Signal-to-noise ratio (SNR), but the invention should not be limited thereto, wherein different signal environment parameters have different priorities.

An embodiment of the invention provides user equipment (UE). The UE comprises a processor and a memory device. The processor obtains a candidate cell group and selects a first candidate cell sub-group from the candidate cell group according to the communication ability supported by each candidate cell of the candidate cell group. The memory device is coupled to the processor. The processor selects a camping cell of the UE from the first candidate cell sub-group.

The methods of the UE camping on the camping cell comprise cell selection, cell reselection and cell handover.

Other aspects and features of the invention will become apparent to those with ordinary skill in the art upon review of the following descriptions of specific embodiments of cell selection methods and UE.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1is a block diagram of a mobile communications system100according to an embodiment of the invention. The system100comprises User Equipment (UE)110and a service network120. The UE110may be a mobile communications device, such as a cellular phone, a smartphone modem processor, a data card, a laptop stick, a mobile hotspot, a USB modem, a tablet, etc.

The UE110may comprise at least a baseband signal processing device111, a radio frequency (RF) signal processing device112, a processor113, a memory device114, and an antenna module comprising at least one antenna. Note that, in order to clarify the concept of the invention,FIG. 1presents a simplified block diagram in which only the elements relevant to the invention are shown. However, the invention should not be limited to what is shown inFIG. 1.

The RF signal processing device112may receive RF signals via the antenna and process the received RF signals to convert the received RF signals to baseband signals to be processed by the baseband signal processing device111, or receive baseband signals from the baseband signal processing device111and convert the received baseband signals to RF signals to be transmitted to a peer communications apparatus. The RF signal processing device112may comprise a plurality of hardware elements to perform radio frequency conversion. For example, the RF signal processing device112may comprise a power amplifier, a mixer, etc.

The baseband signal processing device111may further process the baseband signals to obtain information or data transmitted by the peer communications apparatus. The baseband signal processing device111may also comprise a plurality of hardware elements to perform baseband signal processing. The baseband signal processing may comprise analog-to-digital conversion (ADC)/digital-to-analog conversion (DAC), gain adjustment, modulation/demodulation, encoding/decoding, and so on.

The processor113may control the operations of the baseband signal processing device111and the RF signal processing device112. According to an embodiment of the invention, the processor113may also be arranged to execute the program codes of the software module(s) of the corresponding baseband signal processing device111and/or the RF signal processing device112. The program codes accompanied by specific data in a data structure may also be referred to as a processor logic unit or a stack instance when being executed. Therefore, the processor113may be regarded as being comprised of a plurality of processor logic units, each for executing one or more specific functions or tasks of the corresponding software module(s).

The memory device114may store the software and firmware program codes, system data, user data, etc. of the UE110. The memory device114may be a volatile memory such as a Random Access Memory (RAM); a non-volatile memory such as a flash memory or Read-Only Memory (ROM); a hard disk; or any combination thereof.

According to an embodiment of the invention, the RF signal processing device112and the baseband signal processing device111may collectively be regarded as a radio module capable of communicating with a wireless network to provide wireless communications services in compliance with a predetermined Radio Access Technology (RAT). Note that, in some embodiments of the invention, the UE120may be extended further to comprise more than one antenna and/or more than one radio module, and the invention should not be limited to what is shown inFIG. 1.

In addition, in some embodiments of the invention, the processor113may be configured inside of the baseband signal processing device111, or the UE110may comprise another processor configured inside of the baseband signal processing device111. Thus the invention should not be limited to the architecture shown inFIG. 1.

According to embodiments of the invention, the service network120may be a Global System for Mobile Communications (GSM), a GSM Edge Radio Access Network (GERAN), a Universal Terrestrial Radio Access Network (UTRAN), or an Evolved UTRAN (E-UTRAN), or a 5G new radio (NR) network, but the invention should not be limited thereto.

Note that, the “cell selection” illustrated in the embodiments of the invention can be applied to different applications, such as, cell selection, cell reselection and cell handover. In addition, although in general, the operation of the handover is controlled by the network through the handover command, in real application, the handover is triggered through the measurement report of the UE. Therefore, in the cell selection method provided in the embodiments of the invention, the UE110still can achieve the purpose of selecting the ideal camping cell by selecting the trigger timing of the handover to the target cell or adjusting the timing of sending the measurement report.

In an embodiment of the invention, when the UE110needs to select a cell to camp on, the UE110may obtain a candidate cell group S1according to the neighbor cell information configured by the service network120and the neighbor cell information detected by the UE110. The candidate cell group S1may comprise a plurality of candidate cells to provide to the UE110to select.

After the UE110has obtained the candidate cell group S1, the processor113of the UE110may determine the communication ability supported by each candidate cell of the candidate cell group S1. According to an embodiment of the invention, the processor113of the UE110may obtain information about the communication ability supported by each candidate cell of the candidate cell group S1according to the messages broadcast by the candidate cells and the information learned by the UE110. According to the embodiments of the invention, the messages broadcast by the candidate cells may comprise the information loaded on the master information block (MIB) and the system information block (SIB), but the invention should not be limited thereto. According to the embodiments of the invention, the information learned by the UE110may comprise information about the communication ability of the cell which the UE110camped on before, e.g. the frequency of the cell, the identifier (ID) of the cell, and so on. The information learned by the UE110may be stored in the memory device114. When the candidate cells comprise the cell which the UE110camped on before, the UE110may directly obtain information about the communication ability of the cell from the memory device114.

According to an embodiment of the invention, the communication abilities supported by the candidate cell may comprise whether the candidate cell supports the 5G communication technology (or 5G new radio (NR) technology), whether the candidate cell supports the 4G communication technology (or LTE technology), whether the candidate cell supports the carrier aggregation (CA) technology, and whether the candidate cell supports the 256 Quadrature Amplitude Modulation (QAM) encoding technology, but the invention should not be limited thereto. Different communication abilities may have different priorities. The UE110may sort the candidate cells of the candidate cell group S1by the priorities of different communication abilities. (e.g. according to following orders, support 5G communication technology and 5G NR CA technology>only support 5G communication technology>support 4G communication technology and 4G LTE CA technology>support 4G communication technology and 256QAM encoding technology>merely support 4G communication technology, but the invention should not be limited thereto). After the UE110sorted the candidate cells of the candidate cell group S1, the UE110may select a first candidate cell sub-group S2from the candidate cell group S1according to the sort result. That is to say, the UE110may select a first candidate cell sub-group S2from the candidate cell group S1according the communication ability supported by each candidate cell of the candidate cell group S1and the communication ability supported by the UE110. For example, if the cell A and cell B are 4G cells (LTE cells), and the difference between the cell A and cell B is that cell A supports CA technology, but cell B does not support CA technology, the priority of the cell A will be higher than the priority of cell B. The UE110may select the cell A to be the camping cell first. However, in the UE110does not support the CA technology itself, the UE110may concern other abilities of the cells (e.g. the network resources provided by the candidate cells, and the signal environment parameters of the candidate cells).

After the UE110selected a first candidate cell sub-group S2from the candidate cell group S1, if the first candidate cell sub-group S2merely comprises a candidate cell, the UE110may select the candidate cell to be the camping cell, and start to try to camp on the candidate cell. If the first candidate cell sub-group S2comprises at least two candidate cells, the UE110select a second candidate cell sub-group S3from the first candidate cell sub-group S2according to the network resource of each candidate cell of the first candidate cell sub-group S2. For example, if the candidate cell which supports 5G technology has the highest priority and the UE110support the 5G technology, the UE110may select the candidate cell which supports 5G technology from the candidate cell group S1to be the candidate cell in the first candidate cell sub-group S2. If there is only one candidate cell which supports 5G technology in the candidate cell group S1(i.e. the first candidate cell sub-group S2only comprise one candidate cell), the UE110may select the candidate cell to be the camping cell, and start to try to camp on the candidate cell. If there are at least two candidate cells which support 5G technology in the candidate cell group S1, the UE110may select the candidate cells which support 5G technology from the candidate cell group S1to be the candidate cells in the first candidate cell sub-group S2and select a second candidate cell sub-group S3from the first candidate cell sub-group S2according to the network resource of each candidate cell of the first candidate cell sub-group S2.

According to an embodiment of the invention, the network resources of the candidate cell may comprise the bandwidth and the length of the time slot, but the invention should not be limited thereto. Different network resources may have different priorities. The UE110may sort all of the candidate cells of the first candidate cell sub-group S2according to the different priorities of different network resources. For example, if the priority of the bandwidth is higher than the priority of the length of the time slot, when the bandwidth of the candidate cell C of the first candidate cell sub-group S2is 20 MHz and the bandwidth of the candidate cell D of the first candidate cell sub-group S2is 10 MHz, the candidate cell C may have higher priority than the candidate cell D.

The UE110may select a second candidate cell sub-group S3from the first candidate cell sub-group S2according to the sort result. If the second candidate cell sub-group S3only comprises one candidate cell, the UE110may select the candidate cell of the second candidate cell sub-group S3to be the camping cell, and start to try to camp on the cell. If the second candidate cell sub-group S3comprises at least two candidate cells, the UE110may select a camping cell from the second candidate cell sub-group S3according to the signal environment parameters of each candidate cell of the second candidate cell sub-group S3, and start to try to camp on the selected candidate cell. For example, if the candidate cell whose bandwidth is 20 MHz has the highest priority, the UE110may select the candidate cell whose bandwidth is 20 MHz from the first candidate cell sub-group S2to be the candidate cell of the second candidate cell sub-group S3. If there is only one candidate cell whose bandwidth is 20 MHz in the first candidate cell sub-group S2(i.e. the second candidate cell sub-group S3only comprises one candidate cell), the UE110may select the candidate cell to be the camping cell and start to try to camp on the cell. If there are at least two candidate cells whose bandwidths are 20 MHz, the UE110may select the candidate cells whose bandwidths are 20 MHz from the first candidate cell sub-group S2to be the candidate cells of the second candidate cell sub-group S3, and the UE110may select a camping cell from the second candidate cell sub-group S3according to the signal environment parameters of each candidate cell of the second candidate cell sub-group S3, and start to try to camp on the selected candidate cell.

According to an embodiment of the invention, the signal environment parameters of the candidate cell may comprise the signal strength of the candidate cell (e.g. Reference Symbol Received Power (RSRP) and Received Signal Strength Indication (RSSI)) and Signal-to-noise ratio (SNR), but the invention should not be limited thereto. Different signal environment parameters may have different priorities. The UE110may sort all candidate cells of the second candidate cell sub-group S3according to the priorities of different signal environment parameters. For example, if the priority of the signal strength is higher than the priority of the SNR, the UE110may select the candidate cell which has the highest signal strength from the second candidate cell sub-group S3to be the camping cell and start to try to camp on the selected candidate cell.

FIG. 2A-2Bis a flow chart200illustrating a cell selection method according to an embodiment of the invention. The cell selection method can be applied to the communication system100. As shown inFIG. 2A-2B, in step S205, the UE110obtains a candidate cell group S1. In step S205the UE110selects a first candidate cell sub-group S2from the candidate cell group S1according to the communication ability supported by each candidate cell of the candidate cell group S1and the communication ability supported by the UE110. In step S215, the UE110determines whether the first candidate cell sub-group S2only comprises one candidate cell. If the first candidate cell sub-group S2only comprises one candidate cell, step S220is performed. In step S220, the UE110tries to camp on the candidate cell, and determines whether can camp on the candidate cell successfully. If the UE cannot camp on the candidate cell successfully, step S225is performed. In step S225, the UE110determines whether the number of remaining candidate cells after the first candidate cell sub-group S2is subtracted from the candidate cell group S1is 0 (i.e. S1′=S1−S2=Φ (empty set)). If the number of remaining candidate cells is not 0 (i.e. S1′≠0) step S230is performed. In step S230, the UE110may select the remaining candidate cells to be the candidate cells of the candidate cell group S1(i.e. S1is set to S1′).

If the first candidate cell sub-group S2comprises at least two candidate cells, step S235is performed. In step S235, the UE110selects a second candidate cell sub-group S3from the first candidate cell sub-group S2according to the network resource of each candidate cell of the first candidate cell sub-group S2. In step S240, the UE110determines whether the second candidate cell sub-group S3only comprises one candidate cell. If the second candidate cell sub-group S3only comprises one candidate cell, step S245is performed. In step S245, the UE110tries to camp on the candidate cell, and determines whether can camp on the candidate cell successfully. If the UE cannot camp on the candidate cell successfully, step S250is performed. In step S250, the UE110determines whether the number of remaining candidate cells after the second candidate cell sub-group S3is subtracted from the first candidate cell sub-group S2is 0 (i.e. S2′=S2−S3=Φ (empty set)). If the number of remaining candidate cells is not 0 (i.e. S2′≠0), step S255is performed. In step S255, the UE110may select the remaining candidate cells to be the candidate cells of the first candidate cell sub-group S2(i.e. S2is set to S2′), and the method returns to step S235. If the number of remaining candidate cells is 0 (i.e. S2′=0), the method returns to step S225.

If the second candidate cell sub-group S3comprises at least two candidate cells, step S260is performed. In step S260, the UE110selects a camping cell from the second candidate cell sub-group S3according the signal environment parameter of each candidate cell of the second candidate cell sub-group S3. In step S265, the UE110tries to camp on the candidate cell, and determines whether can camp on the candidate cell successfully.

If the UE cannot camp on the candidate cell successfully, step S270is performed. In step S270, the UE110determines whether the number of remaining candidate cells after the candidate cell which the UE110does not camp on successfully is subtracted from the second candidate cell sub-group S3is 0. If the number of remaining candidate cells after the candidate cell which the UE110does not camp on successfully is subtracted from the second candidate cell sub-group S3is not 0, the method returns to step S260. If number of remaining candidate cells after the candidate cell which the UE110does not camp on successfully is subtracted from the second candidate cell sub-group S3is 0, the method returns to step S250.

In some embodiments of the invention, in step S210, the UE110may obtain information about the communication ability supported by each candidate cell of the candidate cell group S1according to the messages broadcast by the candidate cells and the information stored (learned) by the UE110.

In some embodiments of the invention, the communication abilities supported by the candidate cell may comprise whether the candidate cell supports the 5G communication technology (or 5G new radio (NR) technology), whether the candidate cell supports the carrier aggregation (CA) technology, and whether the candidate cell supports the 256 Quadrature Amplitude Modulation (QAM) encoding technology, but the invention should not be limited thereto. Different communication abilities may have different priorities. In some embodiments of the invention, the network resources of the candidate cell may comprise the bandwidth and the length of the time slot, but the invention should not be limited thereto. Different network resources may have different priorities. In some embodiments of the invention, the signal environment parameters of the candidate cell may comprise the signal strength of the candidate cell and Signal-to-noise ratio (SNR), but the invention should not be limited thereto. Different signal environment parameters may have different priorities.

Accordingly, in the cell selection method provided in the embodiments of the invention, the UE110can concern and analyze the communication ability supported by the candidate cell, the network resource provided by the candidate cell, and the signal environment parameters of the candidate cell to select the most appropriate camping cell. Therefore, comparing to current cell selection method (i.e. select the camping cell only according to the signal strengths of the cells), in the cell selection method provided in the embodiments of the invention, the UE110can further concern the real network environment to increase the throughput of the data service.

Use of ordinal terms such as “first”, “second”, “third”, etc., in the disclosure and claims is for description. It does not by itself connote any order or relationship.

The above paragraphs describe many aspects. Obviously, the teaching of the invention can be accomplished by many methods, and any specific configurations or functions in the disclosed embodiments only present a representative condition. Those who are skilled in this technology will understand that all of the disclosed aspects in the invention can be applied independently or be incorporated.