This application claims the priority benefit of Taiwan application serial no. 112121327, filed on Jun. 7, 2023. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification.
This disclosure relates to a wireless communication technology, in particular to a cell selection method.
A terminal device (such as a cell phone) will try to connect to the network after booting. During the connection process, the signal information of the nearby detectable cells (or base stations) is measured and the more suitable cells are selected for connection. This process is called cell selection.
After connecting to the network, the terminal device will continue to observe the network status in order to perform cell selection again in a timely manner, and this process is called cell reselection.
According to the relevant communication standards (e.g., 3GPP TS 38.304), it is known that during cell selection or cell reselection, the terminal device selects a suitable cell based on the signal strength (e.g., SrxLev parameter as defined in 3GPP TS 38.304) and signal quality (e.g., Squal parameter as defined in 3GPP TS 38.304), as well as the matching frequency priorities or radio access technology (RAT_priorities) for the connection.
However, although this selection method allows the terminal device to select a serving cell with high signal strength and good signal quality, the terminal device may not be able to experience good quality of service.
For example, when a cell has experienced network congestion for some reason (e.g., serving too many terminals), it may allow the terminals it serves to experience lower data transfer speeds despite high signal strength and good signal quality.
The disclosure provides a cell selection method, capable of solving the above technical problems.
An embodiment of the disclosure provides a cell selection method adapted to a terminal device. The method includes the following. During performing a cell selection operation on multiple reference base stations, a signal indicator and a network congestion indicator corresponding to each of the reference base stations are obtained. A serving base station is selected from the reference base stations based on the signal indicator and the network congestion indicator corresponding to the each of the reference base stations.
An embodiment of the disclosure provides a cell selection method adapted to a base station. The method includes the following. A signal indicator and a network congestion indicator corresponding to the base station are provided to a terminal device. The signal indicator and the network congestion indicator corresponding to the base station allow the terminal device to perform a cell selection operation.
To make the aforementioned more comprehensive, several embodiments accompanied with drawings are described in detail as follows.
The accompanying drawings are included to provide a further understanding of the disclosure, and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the disclosure and, together with the description, serve to explain the principles of the disclosure.
In different embodiments, the terminal device 11 may represent a user equipment (UE), a mobile station, an advanced mobile station (AMS), or a wireless terminal communication device. In addition, the terminal device 11 may be a mobile phone, a smart phone, a personal computer (PC), a notebook PC, a netbook PC, a tablet PC, a television, a set-top box, a wireless data modem, a game console, a portable device, or a portable multimedia player, etc.
In different embodiments, the base station 12 is, for example, wireless network access point, enhanced node B (eNodeB), advanced base station (ABS), macro-cell base station, pico-cell base station or remote radio head (RRH), gNodeB (gNB), etc., but not limited thereto.
As shown in
In some embodiments, the communication circuit 112 may be a component such as a protocol unit, which may support various wireless network communication protocols such as WiFi HaLow. In other embodiments, the communication circuit 112 may also support global system for mobile communication (GSM), personal handy-phone system (PHS), code division multiple access (CDMA) system, wireless fidelity (Wi-Fi) system or worldwide interoperability for microwave access (WiMAX) signal transmission, but not limited thereto.
In addition, the processor 114 is coupled to the communication circuit 112, and may be a general-purpose processor, a special-purpose processor, a conventional processor, a digital signal processor, multiple microprocessors, one or more microprocessors incorporating digital signal processor cores, controllers, microcontrollers, application specific integrated circuit (ASIC), field programmable gate array (FPGAs), any other kind of integrated circuits, state machines, advanced RISC machine (ARM)-based processors, and similar products.
As shown in
In the embodiment of the disclosure, the terminal device 11 and the base station 12 may cooperate to implement a cell selection method proposed by the disclosure, the details of which are described as follows.
In step S222, the base station 12 provides a signal indicator and a network congestion indicator corresponding to the base station 12 to the terminal device 11.
In one embodiment, the signal indicator corresponding to the base station 12 includes signal strength (such as SrxLev parameter) and signal quality (such as Squal parameter). In addition, the network congestion indicator corresponding to the base station 12 may include a user network throughput determined by the base station 12. In one embodiment, the user network throughput of the base station 12 is, for example, a user-perceived IP throughput determined by the base station 12, but not limited thereto.
In different embodiments, the base station 12 may, for example, use a statistical value (such as an average value) of the user-perceived IP throughput of all terminal devices it serves as a corresponding user network throughput, but not limited thereto.
In a first embodiment, the user network throughput of the base station 12 is, for example, a current user network throughput determined by the base station 12. For example, assuming that the user network throughput determined by the base station 12 at a tth time point (t is a time index) is a certain value, the base station 12 may use this value as the current user network throughput (expressed as Tt), and provide Tt to the terminal device 11.
In a second embodiment, the user network throughput of the base station 12 is, for example, a future user network throughput predicted by the base station 12. For example, assuming that a current time point is the tth time point, the future user network throughput is, for example, a user network throughput corresponding to a later time point. For the sake of illustration, the following assumptions about the future user network throughput corresponding to a (t+1)th time point are made for illustrative purposes only and are not intended to limit possible implementations of the disclosure.
In the second embodiment, the base station 12 may feed at least one historical user network throughput into a predictive model (expressed as M). The predictive model M may predict the future user network throughput (expressed as Tt+1′) in response to the historical user network throughput.
In a first variation of the second embodiment, the predictive model M may include a long short-term memory model. In this case, the future user network throughput Tt+1′ may be expressed as:
T
t+1
′=f
λ(Tt−L, . . . ,Tt) (1)
where Tt−L, . . . , Tt is the historical user network throughput, L is a time window, and fλ(⋅) is the long short-term memory model.
It can be seen from formula (1) that the predictive model M may predict a corresponding network throughput as a future user network throughput Tt+1′ in response to L+1 historical user network throughput (i.e., Tt−L, . . . , Tt), but not limited thereto.
In a second variation of the second embodiment, the predictive model M may include a regression model. In this case, the future user network throughput Tt+1′ can be expressed as:
where ct is a random error value, εt is a constant, and φi is a regression coefficient. In one embodiment, ct is, for example, a Gaussian random variable with an average value of 0 and a standard deviation of σ, but not limited thereto.
Correspondingly, in step S212, during performing a cell selection operation on multiple reference base stations (including, for example, the base station 12), the terminal device 11 obtains the signal indicator and the network congestion indicator corresponding to each of the reference base stations.
In the embodiment of the disclosure, the reference base stations are, for example, base stations for managing a cell to which the terminal device 11 currently belongs (which is, for example, a current serving base station of the terminal device 11), or base stations for managing a cell adjacent to terminal device 11, but not limited thereto.
In this case, the signal indicator corresponding to the each of the reference base stations includes signal strength (such as SrxLev parameter) and signal quality (such as Squal parameter), and the network congestion indicator corresponding to the each of the reference base stations includes the user network throughput determined by the each of the reference base stations (such as the current user network throughput Tt in the first embodiment and/or the future user network throughput Tt+1′ in the second embodiment.
In one embodiment, the terminal device 11 in an idle state (such as RRC_IDLE state) or inactive state (such as RRC_INACTIVE state) may obtain information about intra-frequency cells, inter-frequency cells, inter-RAT cells, etc. from the current serving base station and perform the cell selection operation accordingly.
In the embodiment of the disclosure, the cell selection operation referred to may be broadly understood to also include a cell reselection operation, but may not be limited thereto.
Next, in step S214, the terminal device 11 selects a serving base station from the reference base stations based on the signal indicator and the network congestion indicator corresponding to the each of the reference base stations.
In one embodiment, the terminal device 11 may find at least one candidate base station from the reference base stations based on the signal indicator corresponding to the each of the reference base stations. The signal indicator corresponding to each of the candidate base station satisfies a preset condition.
In one embodiment, for one of the reference base stations (hereinafter referred to as a first reference base station), the terminal device 11 may determine whether the signal strength corresponding to the first reference base station is not lower than a signal strength threshold (for example, 0 dB) and whether the signal quality corresponding to the first reference base station is not lower than a signal quality threshold (for example, 0 dB) to determine whether the first reference base station belongs to the candidate base station.
In response to determining that the signal strength corresponding to the first reference base station is not lower than the signal strength threshold and the signal quality corresponding to the first reference base station is not lower than the signal quality threshold, the terminal device 11 may determine that the signal indicator corresponding to the first reference base station satisfies the preset condition. On the other hand, in response to determining that the signal strength corresponding to the first reference base station is lower than the signal strength threshold or the signal quality corresponding to the first reference base station is lower than the signal quality threshold, the terminal device 11 may determine the signal indicator corresponding to the first reference base station does not satisfy the preset condition, but may not be limited thereto.
In short, the terminal device 11 may find one or more of reference devices whose signal strength is not lower than the signal strength threshold and whose signal quality is not lower than the signal quality threshold as the candidate base station, but may not be limited thereto.
Afterwards, the terminal device 11 may select the serving base station from the candidate base station based on the network congestion indicator corresponding to the each of the candidate base station.
In one embodiment, the terminal device 11 may, for example, use one or more of the candidate base station with a highest user network throughput as the serving base station, but may not be limited thereto. For example, assuming that base station 12, in addition to satisfying the preset condition, is the candidate base station with the highest user network throughput, the terminal device 11 may, for example, select the base station 12 as the serving base station, but may not be limited thereto.
Afterwards, the terminal device 11 may correspondingly perform a subsequent connection procedure (such as a random access procedure) on the selected serving base station (such as the base station 12) to connect to the selected serving base station, but may not be limited thereto.
To sum up, the method proposed by the disclosure may allow the terminal device to select the base station with better signal strength, signal quality, and network congestion indicator (such as the highest user network throughput) as the serving base station, thereby avoiding selection of a more congested base station as a serving base station. This allows the terminal device to experience better data transfer speeds after the cell selection operation, thus improving the user experience.
It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed embodiments without departing from the scope or spirit of the disclosure. In view of the forthcoming, it is intended that the disclosure covers modifications and variations provided that they fall within the scope of the following claims and their equivalents.
Number | Date | Country | Kind |
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112121327 | Jun 2023 | TW | national |