Patent Application
20240284342
The disclosure relates in general to a wireless communication system. More particularly, the disclosure relates to an apparatus and method for controlling downlink transmit power in the wireless communication system.
To meet the demand for wireless data traffic having increased since deployment of 4th generation (4G) communication systems, efforts have been made to develop an improved 5th generation (5G) or pre-5G communication system. Therefore, the 5G or pre-5G communication system is also called a ‘Beyond 4G Network’ or a ‘Post Long Term Evolution (LTE) System’.
The 5G communication system is considered to be implemented in higher frequency (millimeter wave (mmWave)) bands, e.g., 28 GHz or 60 GHz bands, so as to accomplish higher data rates. To decrease propagation loss of the radio waves and increase the transmission distance, the beamforming, massive multiple-input multiple-output (MIMO), Full Dimensional MIMO (FD-MIMO), array antenna, an analog beam forming, large scale antenna techniques are discussed in 5G communication systems.
In addition, in 5G communication systems, development for system network improvement is under way based on advanced small cells, cloud Radio Access Networks (RANs), ultra-dense networks, device-to-device (D2D) communication, wireless backhaul, moving network, cooperative communication, Coordinated Multi-Points (COMP), reception-end interference cancellation and the like.
In the 5G system, Hybrid frequency shift keying (FSK) and quadrature amplitude modulation (QAM) (FQAM) and sliding window superposition coding (SWSC) as an advanced coding modulation (ACM), and filter bank multi carrier (FBMC), non-orthogonal multiple access (NOMA), and sparse code multiple access (SCMA) as an advanced access technology have been developed.
The above information is presented as background information only to assist with an understanding of the disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the disclosure.
Aspects of the disclosure are to address at least the above-mentioned problems and/or disadvantages and to provide at least the advantages described below. Accordingly, an aspect of the disclosure is to provide an apparatus and method for controlling downlink transmit power in a wireless communication system.
Additional aspects will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice of the presented embodiments.
In accordance with an aspect of the disclosure, a method of operating a base station in a wireless communication system is provided. The method includes decreasing, by the base station, a size of a transport block for a data packet when a size of a downlink data packet is less than or equal to a size of a predetermined minimum allocation resource, determining, by the base station, a transmit signal scaling factor for decreasing transmit power of the data packet, and determining, by the base station, the transmit power of the data packet, based on the transmit signal scaling factor.
In accordance with another aspect of the disclosure, a base station in a wireless communication system is provided. The base station includes a transceiver, memory storing one or more computer programs, and one or more processors communicatively coupled to the transceiver and the memory, wherein the one or more computer programs include computer-executable instructions that, when executed by the one or more processors, cause the base station to decrease a size of a transport block for a data packet when a size of a downlink data packet is less than or equal to a size of a predetermined minimum allocation resource, determine a transmit signal scaling factor for decreasing transmit power of the data packet, and determine the transmit power of the data packet, based on the transmit signal scaling factor.
In accordance with another aspect of the disclosure, one or more non-transitory computer-readable storage media storing one or more computer programs including computer-executable instructions that, when executed by one or more processors of a base station, cause the base station to perform operations are provided. The operations include decreasing, by the base station, a size of a transport block for a data packet when a size of a downlink data packet is less than or equal to a size of a predetermined minimum allocation resource, determining, by the base station, a transmit signal scaling factor for decreasing transmit power of the data packet, and determining, by the base station, the transmit power of the data packet, based on the transmit signal scaling factor.
An apparatus and method according to various embodiments of the disclosure may provide an apparatus and method for controlling downlink transmit power in a wireless communication system.
Other aspects, advantages, and salient features of the disclosure will become apparent to those skilled in the art from the following detailed description, which, take in conjunction with the annexed drawings, discloses various embodiments of the disclosure.
The above and other aspects, features, and advantages of certain embodiments of the disclosure will be more apparent from the following description taken in conjunction with the accompanying drawings, in which:
Throughout the drawings, it should be noted that like reference numbers are used to depict the same or similar elements, features, and structures.
The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of various embodiments of the disclosure as defined by the claims and their equivalents. It includes various specific details to assist in that understanding but these are to be regarded as merely exemplary. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the various embodiments described herein can be made without departing from the scope and spirit of the disclosure. In addition, descriptions of well-known functions and constructions may be omitted for clarity and conciseness.
The terms and words used in the following description and claims are not limited to the bibliographical meanings, but, are merely used by the inventor to enable a clear and consistent understanding of the disclosure. Accordingly, it should be apparent to those skilled in the art that the following description of various embodiments of the disclosure is provided for illustration purpose only and not for the purpose of limiting the disclosure as defined by the appended claims and their equivalents.
It is to be understood that the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a component surface” includes reference to one or more of such surfaces.
It should be appreciated that the blocks in each flowchart and combinations of the flowcharts may be performed by one or more computer programs which include instructions. The entirety of the one or more computer programs may be stored in a single memory device or the one or more computer programs may be divided with different portions stored in different multiple memory devices.
Any of the functions or operations described herein can be processed by one processor or a combination of processors. The one processor or the combination of processors is circuitry performing processing and includes circuitry like an application processor (AP, e.g. a central processing unit (CPU)), a communication processor (CP, e.g., a modem), a graphics processing unit (GPU), a neural processing unit (NPU) (e.g., an artificial intelligence (AI) chip), a Wi-Fi chip, a Bluetooth® chip, a global positioning system (GPS) chip, a near field communication (NFC) chip, connectivity chips, a sensor controller, a touch controller, a finger-print sensor controller, a display drive integrated circuit (IC), an audio CODEC chip, a universal serial bus (USB) controller, a camera controller, an image processing IC, a microprocessor unit (MPU), a system on chip (SoC), an integrated circuit (IC), or the like.
Referring to
The base station 100 is a network infrastructure which provides a radio access to the terminals 200 and 300. The base station 100 has a coverage defined as a specific geographic region, based on a distance capable of transmitting a signal. In addition to the term ‘base station’, the base station 100 may be referred to as an ‘Access Point (AP)’, an ‘eNodeB (eNB)’, a ‘5th Generation (5G) node’, a ‘next generation NodeB (gNB)’, a ‘wireless point’, a ‘Transmission/Reception Point (TRP)’, or other terms having equivalent technical meanings.
As a device used by a user, each of the terminal 200 and the terminal 300 communicates with the base station 100 through the radio channel. In addition to the term ‘terminal’, each of the terminals 200 and 300 may be referred to as a ‘User Equipment (UE)’, a ‘Customer Premises Equipment (CPE)’, a ‘mobile station’, a ‘subscriber station’, a ‘remote terminal’, a ‘wireless terminal’, an ‘electronic device’, a ‘user device’, or other terms having equivalent technical meanings.
Referring to
The processor 110 controls overall operations of the base station. For example, the processor 110 transmits and receives a signal via the transceiver 120. Further, the processor 110 writes data to the memory 130, and reads the data. In addition, the processor 110 may control downlink transmit power via the downlink transmit power control device 140. The processor 110 may include at least one processor.
The transceiver 120 is coupled to the processor 110 to transmit and receive a signal. Accordingly, all or part of the transceiver 120 may be referred to as a ‘transmitter’, a ‘receiver’, or a ‘transceiver’.
The memory 130 is coupled to the processor 110 to store data such as a basic program, application program, configuration information, or the like for an operation of the base station. The memory 130 may be constructed of volatile memory, non-volatile memory, or a combination of the volatile memory and the non-volatile memory. In addition, the memory 130 provides stored data according to a request of the processor 110.
The downlink transmit power control device 140 is coupled to the processor 110 to control downlink transmit power required to transmit a signal from the base station to a terminal.
Various embodiments of the disclosure relate to an apparatus and method for controlling downlink transmit power of a cellular base station system according to a downlink traffic condition. The advance of a communication transmission/reception technique and device results in an increase in a Multiple-Input/Multiple-Output (MIMO) layer count or a modulation order, thereby improving spectral efficiency applied to wireless communication day by day. A communication method having the improved spectral efficiency may improve a transmission data-rate, but performance thereof may be significantly affected by surrounding environments, in particular, power of an interference signal transmitted from a neighboring base station.
In particular, in an urban area or the like in which a data traffic demand is densely concentrated, a plurality of base station devices and antennas thereof are installed in the form of neighboring cells to satisfy a high system data capacity requirement, thereby serving for a terminal in cell coverage. In this case, the terminal concurrently receives signals transmitted from different base stations in a cell boundary region, which leads to performance deterioration caused by Inter-Cell Interference (ICI).
In order to minimize such performance degradation, each base station shall be able to transmit a signal with power as much as required only when transmission is necessary. In downlink transmission of the base station in a practical commercial network in numerous instances, there are only some cases where a big-sized file requiring a high transfer rate is downloaded or high-definition video is downloaded, and downlink signals of most of base stations may be constructed of common signals which are always on to maintain coverage of a system for all users or data packets which are transmitted to each user but are small in size because a high transfer rate is not required. Examples of such downlink data include a text-based web download or control messages for each higher layer/application.
Cellular communication systems of previous generations including 4G LTE have many signals, such as a pilot channel or a Cell-Specific Reference Signal (CRS), which shall be always transmitted persistently by a base station. However, in a standard of a newly defined 5th Generation New Radio (5G NR) system, the base station is allowed to transmit limitedly only when data required in practice is transmitted to one, some, or all users in coverage, thereby reducing influence of inter-cell interference. Therefore, the inter-cell interference occurs due to transmission of short data packets not requiring a significantly high transfer rate in other neighboring cells, resulting in deterioration of downlink transmission quality in a cell requiring a high transfer rate. In particular, in the latest standard such the 5G NR in which interference caused by a signal to be transmitted always is minimized, it may have a grant impact on average network quality. For this reason, in order to improve a high transfer rate experienced by a user in a cellular system, there is a need for a device which controls transmit power transmitted to short data packets to be less than a required level.
The prior art related to various embodiments of the disclosure is as follows.
The prior arts [1] and [2] propose calculating of allocation power through an SNIR required for each terminal, based on reception intensity and downlink quality information of terminals.
The prior art [3] is used limitedly for a 4G LTE system which uses a Cell-specific Reference Signal (CRS). It is not for a data channel according to a feature of a system which operates the CRS, and may be used for adjusting network coverage of each macro/pico/femto cell in a heterogeneous network.
Another prior art [4] assumes that all information for downlink transmit power transmitted by each base station, receive power of a base station's signal desired by terminals in each base station (after path loss), and interference signal receive power of a neighboring base station's signal may be collected and shared in one place. That is, it is assumed that an additional downlink transmit power control server coupled to all base stations may be present, or all base stations may exchange related information with each other on a real-time basis. With a magnitude of signal power of all base stations, received by each terminal, a Signal-to-Interference Ratio (SIR) of the terminal and an achievable data-rate under this condition may be estimated. Therefore, each base station may determine its own output level so that a sum of the achievable data-rates for all terminals for which a downlink service is executed at a specific timing has a maximum value.
As a more detailed method than the above method, the prior art [5] proposes a method in which downlink loading information is mutually exchanged by two or more base stations (through an additional server or the like between a plurality of base stations) and a budge of transmit power is determined, thereby increasing/decreasing downlink transmission. In particular, the prior art [6] proposes a similar operation using a Mobile Switching Center (MSC)/Base Station Controller (BSC) in Third Generation Direct Sequence-Code Division Multiple Access (3G DS-CDMA).
The aforementioned prior art has the following problem.
A method of the prior arts [1] and [2] predicts a Signal-to-noise and Interference Ratio (SINR) in a downlink data channel received by a terminal from reception sensitivity and downlink quality information measured by terminals by using a downlink reference signal. However, the latest communication standards, including a 5G NR system, differs from the conventional communication system in which a downlink reference signal such as a CRS is always transmitted to have a constant reception electric field even within a data channel. In the latest communication standards, a terminal is not able to directly measure interference in a neighboring cell within a downlink data channel transmitted for each user, and is able to additionally measure an SINR including interference of neighboring cells only from reference signals, e.g., a Channel State Information-Reference Signal (CSI-RS) or a Synchronization Signal Block (SSB), broadcast for all users. Since an interference amount of a neighboring cell, measured in a reference signal broadcast with a regular period does not have the same pattern as an interference amount of a neighboring cell in a data interference channel, which occurs only at the presence of each user traffic transmission, a mismatch may occur between SINRs measured by a terminal. In particular, when a base station uses a massive MIMO system constructed of a plurality of antennas, there is a significant difference in a broadcast signal radiated throughout a cell, a signal and interference power in a downlink data channel to which beamforming for a specific user is applied, and an SINR estimated by using this.
A method of the prior art [4] may provide mathematically a highest transmission rate sum for all cells. However, in order for this function to operate properly, first, a terminal shall measure receive power separately for a downlink signal of a neighboring base station (step a). Next, receive power of each neighboring base station and a serving base station shall be all reported to the serving base station (step b). In a next step, receive power information reported to each base station is collected to one downlink transmit power control server, or is mutually shared to base stations in all networks (step c). Finally, based on the collected receive power information, the downlink transmit power control server calculates transmit power of each base station such that an achievable data-rate has a maximum sum, and transmits it to each base station (step d). Alternatively, each computational process is performed independently in each individual base station.
Such a complex configuration step is not realistic to implement in practice due to the following constraint. First, in the step (a), measurement of a terminal in practical implementation is significantly limited in general since calculation capability of the terminal is persistently consumed. In the next step (b), a report for a measurement result also has an impact on uplink resource consumption and reception performance including uplink coverage. Therefore, for a downlink transmit power control operation in a practical commercial network, there is a need for a method also applicable to a limited terminal's measurement information and report (in particular, minimizing the use of measuring and reporting for a base station of a neighboring different cell).
In addition, in the final processes in which measurement information of a terminal in each base station is collected for the entire network to calculate an achievable data-rate of each terminal from the collected measurement information, even though it is possible to calculate it under the assumption that there is not many base stations in a network to be considered, it is impossible in practice to calculate it on a real-time basis in an environment of operating a practical network in which significantly many base stations are present in the same band.
In particular, for a massive MIMO base station, downlink transmit power is not evenly radiated in all directions, but is transmitted through a user-specific beam. Therefore, transmission/reception signals and beam information for all considerable base stations and terminals shall be measured, reported, and collected by considering even an influence of a beam, as to a specific beam used in transmission instantaneously in each base station and also a specific magnitude of an interference reception signal received by a terminal belonging to another base station when transmission is performed using the beam.
Even if it may be assumed that it is possible to secure such information, since information such as a beam direction or the like is significantly changed just by a change in an amount of a resource to be allocated, a target terminal served by some base stations, or the like, it is impossible to realize a data rate calculated based on previous information as practical performance.
Various embodiments of the disclosure have the following purpose.
In particular, in a cellular system served through a plurality of base stations densely installed in a narrow region, a method of controlling downlink transmit power is necessary to improve downlink reception quality of an inter-cell boundary region. For a practical operation, there is a need for an apparatus and method for simply controlling downlink transmit power of each serving cell by utilizing, to the minimum extent possible, information on a terminal's electric field environment of a neighboring cell, a beamforming shape, transmit power density, or the like.
Among device configurations described below, a block may be replaced with a unit, a configuration, a device, or a combination of devices or the like.
The downlink transmit power control device 140 according to various embodiments of the disclosure is for controlling base station's transmit signal power of a downlink data signal having a small payload size in particular among terminals served in a cellular system.
The downlink transmit power control device 140 according to various embodiments of the disclosure includes an uplink data/control receiver block 141, a downlink long-term link adaptation block 142, a downlink resource allocation block 143, a ‘spectral efficiency decrease for short packet’ block 144, a downlink transmit(back-off) power calculator block 145, and a downlink baseband transmitter block 146.
The downlink transmit power control device 140 transmits HARQ ACK information and CSI report information to the long-term link adaptation block 142.
An example of link adaptation of a downlink channel and a resource allocation process will be described in relation to an operation of the downlink transmit power control device proposed in various embodiments of the disclosure.
In general, allocation information for downlink transmission may be determined only with two blocks, i.e., the aforementioned downlink long-term link adaptation block 142 and the downlink resource allocation block 143.
In various embodiments of the disclosure, in addition to the two blocks, i.e., the aforementioned long-term link adaptation block 142 and the downlink resource allocation block 143, processing of the ‘spectral efficiency decrease for short packet’ block 144, the downlink transmit (back-off) power calculator block 145, and the downlink baseband transmitter block 146 is disclosed. Accordingly, in particular, although a higher layer downlink transmission queue has a small data size, a more effective transmission method in terms of transmission energy consumption of a base station and interference on neighboring cells is proposed as to downlink channel transmission having a restriction in a minimum allocation resource size.
BackOff[dB]=min(MAXBackOff,reqSINR(MCSlong-term,MIMO_Layerlong-term)−reqSINR(MCSadjust,MIMO_Layeradjust)+OffsetQoS) Equation 1
A data bit-stream which first has undergone channel coding for error correction in the channel encoder 146-1 is transformed in the form of a QAM symbol such as QPSK, 16QAM, 64QAM, 256QAM, or 1024QAM via the QAM modulator 146-2. Ever since this operation, a transmit signal includes physical concept of magnitude. Therefore, an output symbol of each QAM modulator 146-2 may be multiplied by the transmit signal scaling factor transferred in a previous device to adjust transmit signal power.
Referring to
Hereinafter, an operation and method of a device according to various embodiments of the disclosure will be described.
According to various embodiments of the disclosure, compared to a transfer rate obtained as a result of long-term adaptation of a specific user, an embodiment of a case where data in a queue is small and thus is transmitted with a much lower transfer rate may be considered.
The downlink transmit power control device 140 for controlling downlink transmit power of a short packet proposed in various embodiments of the disclosure typically includes the following three configuration.
The embodiment of
The downlink transmit power control device 140 performing the embodiment of
Before operation 701, the downlink transmit power control device 140 may receive terminal's HARQ ACK information, terminal's uplink data including a CSI report, and/or uplink control information. The downlink transmit power control device 140 may determine an MCS and MIMO layer count for a terminal by performing long-term link adaptation, based on the received terminal's uplink data and/or uplink control information. The downlink transmit power control device 140 may allocate a downlink resource for a user terminal, based on the determined MCS and MIMO layer count, by considering a size of a downlink data payload received from a higher layer. In this process, the downlink transmit power control device 140 may determine a size of a transport block for the user terminal.
In operation 701, the downlink transmit power control device 140 decreases the transport block size for a short packet. The short packet refers to a data packet when a data size of a queue is less than or equal to a specific ratio compared to the transport block size determined by allocation information of a slot, or when the data size of the queue is less than or equal to a pre-defined minimum allocation resource size. If the data size of the queue is significantly small compared to the transport block size determined by the allocation information of the slot, the downlink transmit power control device 140 decreases an MCS or a MIMO layer count such that the transport block size is greater than or equal to queue data but is as close to a size of the queue data as possible.
In operation 703, for a short packet having a decreased transport block size, the downlink transmit power control device 140 determines the transmit signal scaling factor capable of decreasing transmit power to the maximum extent possible while maintaining required performance.
BackOff[dB]=min(MAXBackOff,reqSINR(MCSlong-term,MIMO_Layerlong-term)−reqSINR(MCSadjust,MIMO_Layeradjust)+OffsetQoS) Equation 2
In operation 705, the downlink transmit power control device 140 changes a magnitude of a QAM signal constituting a downlink data channel by using a transmit signal scaling factor to adjust/determine a magnitude of downlink transmit power.
A data bit-stream which first has undergone channel coding for error correction in the channel encoder 146-1 is transformed in the form of a QAM symbol such as QPSK, 16QAM, 64QAM, 256QAM, or 1024QAM via the QAM modulator 146-2. Ever since this operation, a transmit signal includes physical concept of magnitude. Therefore, an output symbol of each QAM modulator 146-2 may be multiplied by the transmit signal scaling factor transferred in a previous device to adjust transmit signal power.
After operation 703, the downlink transmit power control device 140 may transmit downlink data to a terminal, based on the determined downlink transmit power.
Methods based on the embodiments disclosed in the claims and/or specification of the disclosure may be implemented in hardware, software, or a combination of both.
When implemented in software, computer readable recording medium for storing one or more programs (i.e., software modules) may be provided. The one or more programs stored in the computer readable recording medium are configured for execution performed by one or more processors in the electronic device. The one or more programs include instructions for allowing the electronic device to execute the methods based on the embodiments disclosed in the claims and/or specification of the disclosure.
The program (i.e., the software module or software) may be stored in random access memory (RAM), non-volatile memory including flash memory, Read Only Memory (ROM), Electrically Erasable Programmable Read Only Memory (EEPROM), a magnetic disc storage device, a Compact Disc-ROM (CD-ROM), Digital Versatile Discs (DVDs) or other forms of optical storage devices, and a magnetic cassette. Alternatively, the program may be stored in memory configured in combination of all or some of these storage media. In addition, the configured memory may be plural in number.
Further, the program may be stored in an attachable storage device capable of accessing the electronic device through a communication network such as the Internet, an Intranet, a Local Area Network (LAN), a Wide LAN (WLAN), or a Storage Area Network (SAN) or a communication network configured by combining the networks. The storage device may have access to a device for performing an embodiment of the disclosure via an external port. In addition, an additional storage device on a communication network may have access to the device for performing the embodiment of the disclosure.
In the aforementioned specific embodiments of the disclosure, a component included in the disclosure is expressed in a singular or plural form according to the specific embodiment proposed herein. However, the singular or plural expression is selected properly for a situation proposed for the convenience of explanation, and thus the various embodiments of the disclosure are not limited to a single or a plurality of components. Therefore, a component expressed in a plural form may also be expressed in a singular form, or vice versa.
While the disclosure has been shown and described with reference to various embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the disclosure as defined by the appended claims and their equivalents.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2021-0187732 | Dec 2021 | KR | national |
| 10-2022-0017623 | Feb 2022 | KR | national |
This application is a continuation application, claiming priority under § 365(c), of an International application No. PCT/KR2022/018712, filed on Nov. 24, 2022, which is based on and claims the benefit of a Korean patent application number 10-2021-0187732, filed on Dec. 24, 2021, in the Korean Intellectual Property Office, and of a Korean patent application number 10-2022-0017623, filed on Feb. 10, 2022, in the Korean Intellectual Property Office, the disclosure of each of which is incorporated by reference herein in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/KR2022/018712 | Nov 2022 | WO |
| Child | 18650797 | US |
