WO2023065275A1

WO2023065275A1 - Apparatuses, methods, and computer readable media for association between user equipment device and access point

Info

Publication number: WO2023065275A1
Application number: PCT/CN2021/125525
Authority: WO
Inventors: Zhihang Li
Original assignee: Nokia Shanghai Bell Co., Ltd.; Nokia Solutions And Networks Oy; Nokia Technologies Oy
Priority date: 2021-10-22
Filing date: 2021-10-22
Publication date: 2023-04-27
Also published as: CN118140533A

Abstract

Disclosed are apparatuses for a UE-AP association. An example apparatus may include at least one processor and at least one memory. The at least one memory may include computer program code, and the at least one memory and the computer program code may be configured to, with the at least one processor, cause the apparatus as a user equipment device in a cell free communication system to perform establishing a connection with a primary access point in the cell free communication system by a random access procedure, and receiving, from the primary access point, an accessing threshold specific to the user equipment device. Related apparatuses, methods and computer readable media are also disclosed.

Description

APPARATUSES, METHODS, AND COMPUTER READABLE MEDIA FOR ASSOCIATION BETWEEN USER EQUIPMENT DEVICE AND ACCESS POINT

TECHNICAL FIELD

Various embodiments relate to apparatuses, methods, and computer readable media for association between user equipment (UE) device and access point (AP) .

BACKGROUND

A cell free massive multiple-input multiple-output (MIMO) communication system generally comprises a central processing unit (CPU) , a plurality of APs, and a plurality of UE devices. The APs connect to the CPU through fronthaul links and serve UE devices through air interfaces. In the cell free communication system, usually, the UE devices are assigned with the same time/frequency resources, and distributed APs can simultaneously provide services to a smaller set of UE devices over the same time/frequency resources. When an AP, as a serving AP of a UE device, contributes a useful signal to the UE device, the AP may transmit an interference signal to another UE device if the AP is not the serving AP of the another UE device. Therefore, an association between the UE device and the AP, which may be termed as UE-AP association, may affect a signal to interference plus noise ratio (SINR) of the respective UE device and result in different system performances.

SUMMARY

A brief summary of exemplary embodiments is provided below to provide basic understanding of some aspects of various embodiments. It should be noted that this summary is not intended to identify key features of essential elements or define scopes of the embodiments, and its sole purpose is to introduce some concepts in a simplified form as a preamble for a more detailed description provided below.

In a first aspect, disclosed is an apparatus. The apparatus may include at least one processor and at least one memory. The at least one memory may include computer program code, and the at least one memory and the computer program code may be configured to, with the at least one processor, cause the apparatus as a user equipment device in a cell free communication system to perform establishing a connection with a primary access point in the cell free communication system by a random access procedure, and receiving, from the primary access point, an accessing threshold specific to the user equipment device.

In some example embodiments, the at least one memory and the computer program code may be further configured to, with the at least one processor, cause the apparatus to further perform establishing a connection with at least one secondary access point in the cell free communication system by a random access procedure according to the accessing threshold.

In some example embodiments, a quality of a downlink signal received from the primary access point may be higher than a quality of a downlink signal received from at least one access point in the cell free communication system other than the primary access point.

In a second aspect, disclosed is an apparatus. The apparatus may include at least one processor and at least one memory. The at least one memory may include computer program code, and the at least one memory and the computer program code may be configured to, with the at least one processor, cause the apparatus as a network device associated with an access point in a cell free communication system to perform establishing a connection with a user equipment device in the cell free communication system, by a random access procedure, transmitting, to a central processing unit in the cell free communication system, a quality of an uplink signal received from the user equipment device, receiving, from the central processing unit, an accessing threshold specific to the user equipment device, and transmitting, to the user equipment device, the accessing threshold.

In a third aspect, disclosed is an apparatus. The apparatus may include at least one processor and at least one memory. The at least one memory may include computer program code, and the at least one memory and the computer program code may be configured to, with the at least one processor, cause the apparatus as a network device associated with a central processing unit in a cell free communication system to perform receiving, from a plurality of access points in the cell free communication system, qualities of uplink signals received by respective access points from a plurality of user equipment devices in the cell free communication system, determining an accessing threshold specific to a user equipment device of the plurality of user equipment devices based on the qualities of the uplink signals, and transmitting, to a primary access point of the user equipment device among the plurality of access points, the accessing threshold.

In some example embodiments, the accessing threshold may be determined further based on pilot sequences assigned for the plurality of user equipment devices and/or transmitting powers allocated to the plurality of user equipment device.

In some example embodiments, the at least one memory and the computer program code may be further configured to, with the at least one processor, cause the apparatus to further perform refraining from transmitting, to the plurality of access points other than the primary access point, the accessing threshold.

In some example embodiments, a quality of a downlink signal received by the user equipment device from the primary access point may be higher than a quality of a downlink signal received by the user equipment device from at least one access point of the plurality of access points other than the primary access point.

In a fourth aspect, disclosed is a method performed by a user equipment device in a cell free communication system. The method may include establishing a connection with a primary access point in the cell free communication system by a random access procedure, and receiving, from the primary access point, an accessing threshold specific to the user equipment device.

In some example embodiments, the method may further include establishing a connection with at least one secondary access point in the cell free communication system by a random access procedure according to the accessing threshold.

In a fifth aspect, disclosed is a method performed by a network device associated with an access point in a cell free communication system. The method may include establishing a connection with a user equipment device in the cell free communication system, by a random access procedure, transmitting, to a central processing unit in the cell free communication system, a quality of an uplink signal received from the user equipment device, receiving, from the central processing unit, an accessing threshold specific to the user equipment device, and transmitting, to the user equipment device, the accessing threshold.

In a sixth aspect, disclosed is a method performed by a network device associated with a central processing unit in a cell free communication system. The method may include receiving, from a plurality of access points in the cell free communication system, qualities of uplink signals received by respective access points from a plurality of user equipment devices in the cell free communication system, determining an accessing threshold specific to a user equipment device of the plurality of user equipment devices based on the qualities of the uplink signals, and transmitting, to a primary access point of the user equipment device among the plurality of access points, the accessing threshold.

In some example embodiments, the method may further include refraining from transmitting, to the plurality of access points other than the primary access point, the accessing threshold.

In a seventh aspect, disclosed is an apparatus. The apparatus as a user equipment device in a cell free communication system may include means for establishing a connection with a primary access point in the cell free communication system by a random access procedure, and means for receiving, from the primary access point, an accessing threshold specific to the user equipment device.

In some example embodiments, the apparatus may further include means for establishing a connection with at least one secondary access point in the cell free communication system by a random access procedure according to the accessing threshold.

In an eighth aspect, disclosed is an apparatus. The apparatus as a network device associated with an access point in a cell free communication system include means for establishing a connection with a user equipment device in the cell free communication system, by a random access procedure, means for transmitting, to a central processing unit in the cell free communication system, a quality of an uplink signal received from the user equipment device, means for receiving, from the central processing unit, an accessing threshold specific to the user equipment device, and means for transmitting, to the user equipment device, the accessing threshold.

In a ninth aspect, disclosed is an apparatus. The apparatus as a network device associated with a central processing unit in a cell free communication system include means for receiving, from a plurality of access points in the cell free communication system, qualities of uplink signals received by respective access points from a plurality of user equipment devices in the cell free communication system, means for determining an accessing threshold specific to a user equipment device of the plurality of user equipment devices based on the qualities of the uplink signals, and means for transmitting, to a primary access point of the user equipment device among the plurality of access points, the accessing threshold.

In some example embodiments, the accessing threshold may be determined further based on pilot sequences assigned for the plurality of user equipment devices and/or transmitting powers allocated to the plurality of user equipment devices.

In some example embodiments, the apparatus may further include means for refraining from transmitting, to the plurality of access points other than the primary access point, the accessing threshold.

In a tenth aspect, a computer readable medium is disclosed. The computer readable medium may include instructions stored thereon for causing an apparatus as a user equipment device in a cell free communication system to perform establishing a connection with a primary access point in the cell free communication system by a random access procedure, and receiving, from the primary access point, an accessing threshold specific to the user equipment device.

In some example embodiments, the computer readable medium may further include instructions stored thereon for causing the apparatus to further perform establishing a connection with at least one secondary access point in the cell free communication system by a random access procedure according to the accessing threshold.

In an eleventh aspect, a computer readable medium is disclosed. The computer readable medium may include instructions stored thereon for causing an apparatus as a network device associated with an access point in a cell free communication system to perform establishing a connection with a user equipment device in the cell free communication system, by a random access procedure, transmitting, to a central processing unit in the cell free communication system, a quality of an uplink signal received from the user equipment device, receiving, from the central processing unit, an accessing threshold specific to the user equipment device, and transmitting, to the user equipment device, the accessing threshold.

In a twelfth aspect, a computer readable medium is disclosed. The computer readable medium may include instructions stored thereon for causing an apparatus as a network device associated with a central processing unit in a cell free communication system to perform receiving, from a plurality of access points in the cell free communication system, qualities of uplink signals received by respective access points from a plurality of user equipment devices in the cell free communication system, determining an accessing threshold specific to a user equipment device of the plurality of user equipment devices based on the qualities of the uplink signals, and transmitting, to a primary access point of the user equipment device among the plurality of access points, the accessing threshold.

In some example embodiments, the computer readable medium may further include instructions stored thereon for causing the apparatus to further perform refraining from transmitting, to the plurality of access points other than the primary access point, the accessing threshold.

Other features and advantages of the example embodiments of the present disclosure will also be apparent from the following description of specific embodiments when read in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of example embodiments of the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

Some example embodiments will now be described, by way of non-limiting examples, with reference to the accompanying drawings.

FIG. 1 shows an exemplary sequence diagram for a UE-AP association according to embodiments of the present disclosure.

FIG. 2 shows a flow chart illustrating an example procedure for determining an accessing threshold specific to UE devices according to embodiments of the present disclosure.

FIG. 3 shows a flow chart illustrating an example method for the UE-AP association according to embodiments of the present disclosure.

FIG. 4 shows a flow chart illustrating an example method for the UE-AP association according to embodiments of the present disclosure.

FIG. 5 shows a flow chart illustrating an example method for the UE-AP association according to embodiments of the present disclosure.

FIG. 6 shows a block diagram illustrating an example apparatus for the UE-AP association according to embodiments of the present disclosure.

FIG. 7 shows a block diagram illustrating an example apparatus for the UE-AP association according to embodiments of the present disclosure.

FIG. 8 shows a block diagram illustrating an example apparatus for the UE-AP association according to embodiments of the present disclosure.

FIG. 9 shows a block diagram illustrating an example apparatus for the UE-AP association according to embodiments of the present disclosure.

FIG. 10 shows a block diagram illustrating an example apparatus for the UE-AP association according to embodiments of the present disclosure.

FIG. 11 shows a block diagram illustrating an example apparatus for the UE-AP association according to embodiments of the present disclosure.

Throughout the drawings, same or similar reference numbers indicate same or similar elements. A repetitive description on the same elements would be omitted.

DETAILED DESCRIPTION

Herein below, some example embodiments are described in detail with reference to the accompanying drawings. The following description includes specific details for the purpose of providing a thorough understanding of various concepts. However, it will be apparent to those skilled in the art that these concepts may be practiced without these specific details. In some instances, well known circuits, techniques and components are shown in block diagram form to avoid obscuring the described concepts and features.

In the cell free communication system, a distributed architecture may shorten distances between the UE devices and the serving APs, and thus the system performance can be improved by enhancing a received signal quality (RSQ) . Further, a coordinated transmission among the APs can improve the system performance by suppressing the interference. In the cell free communication system including a set of APs, a UE device may select to connect to at least one AP from the set of APs according to an accessing threshold (AccThr) . According to embodiments of the present disclosure, an improved UE-AP association is provided for the cell free communication system, such that the system performance in various metrics may be improved.

FIG. 1 shows an exemplary sequence diagram for the UE-AP association according to embodiments of the present disclosure. Referring to the FIG. 1, a UE device 110 may represent any one of a plurality of UE devices in a cell free communication system. A network device 120 and a network device 130 are associated with and may function as APs, respectively, in the cell free communication system. The network device 120 is associated with a primary AP (PAP) serving the UE device 110, which will be explained later, and the network device 130 is associated with an AP representing any one of a plurality of APs in the cell free communication system other than the PAP of the UE device 110. A network device 140 is associated with and may function as the CPU in the cell free communication system.

The network device 120 and the network device 130, which may represent any APs in the cell free communication system, periodically transmit downlink (DL) signals to the UE device 110, which may represent any UE device in the cell free communication system. For example, the network device 120 may transmit a DL signal 122 to the UE device 110, and the network device 130 may transmit a DL signal 132 to the UE device 110. The DL signal 122 and/or the DL signal 132 may be, e.g., a physical broadcast channel (PBCH) , a cell-specific reference signal (CRS) , etc.

Receiving the DL signals such as the DL signal 122 and the DL signal 132, in an operation 112, the UE device 110 may measure the RSQ for respective DL signal, such as the DL signal 122 and the DL signal 132. The RSQ may be, e.g., a reference signal received power (RSRP) , a signal to noise ratio (SNR) , a SINR, etc. Then, the UE device 110 may transmit an uplink (UL) signal 114 to the plurality of APs, such as the APs associated with the network device 120 and the network device 130. The UL signal 114 may be, e.g., a preamble, a sounding reference signal (SRS) , etc. On the AP side, an AP receives UL signals such as the UL signal 114 from respective UE devices such as the UE device 110.

In an operation 150, the UE device 110 may establish a connection with the network device 120 by a random access (RA) procedure. In an embodiment, the operation 150 may be performed before receiving the AccThr. As is mentioned above, in the cell free communication system, the network device 120 is associated with the PAP of the UE device 110. In an embodiment, the quality of a DL signal received by the UE device 110 from the PAP is higher than a quality of a DL signal received by the UE device 110 from at least one AP in the cell free communication system other than the PAP. For example, at the UE device 110, the RSQ of the DL signal 122 from the network device 120 is higher than the RSQ of the DL signal 132 from the network device 130. The UE device 110 may select from the plurality of APs the AP from which the RSQ of the DL signal is largest as the PAP to establish the connection in the operation 150.

At the AP side, the plurality of APs may measure a RSQ of a UL signal from the UE device 110. For example, in an operation 124, the network device 120 may measure the RSQ 126 of the UL signal 114, and in an operation 134, the network device 130 may measure the RSQ 136 of the UL signal 114. The RSQ may be, e.g., a RSRP, a SNR, a SINR, etc. Then, the network device 120 may transmit, to the network device 140, the quality of the UL signal 114 received from the UE device 110. For example, the network device 120 may transmit the RSQ 126 to the network device 140. Since an AP receives UL signals from respective UE devices, the AP may measure RSQs of the UL signals from the plurality of UE devices. Thus, for example, the network device 120 may transmit, to the network device 140, the RSQs of the UL signals from the plurality of UE devices.

At the CPU side, the network device 140 may receive, from the plurality of APs, the qualities of the UL signals received by respective APs from the plurality of UE devices. Thus, according to the received RSQs, the network device 140 may be aware of the PAP for respective UE device. Alternatively or additionally, the respective UE deice may notify the network device 140 of the PAP serving the UE device.

In an operation 142, the network device 140 may determine an AccThr 144 specific to the UE device 110 based on the qualities of the UL signals. Similarly, in the operation 142, the network device 140 may also determine the AccThrs specific to other UE devices of the plurality of UE devices.

An example for determining a UE-specific AccThr such as the AccThr 144 specific to the UE device 110 is described below.

It may be assumed that a cell free massive MIMO uplink system comprises M APs and K UE devices. The APs and the UE devices are equipped with a single antenna, respectively, and are randomly distributed within a large area. The APs connect to the CPU of the system through fronthaul links which offer error free and infinite capacity to the CPU. Each UE device accesses in several nearby APs by measuring the RSQs, sorting the RSQs related to the plurality of APs and the UE device according to a descending order, and selecting a set of APs where the ratio of the sum of the RSQs of the set of APs to the sum of the RSQs of the plurality of APs is larger than the AccThr. Assuming that the system adopts time domain duplexing, the coherence interval is divided into two phases: uplink channel estimation and downlink data transmission.

The channel model between AP m and UE device k can be denoted as

Where β _mk is a large scale fading and h _mk is a small scale fading, m=1, 2, ... M, k=1, 2, ... K. Assuming that h _mk are independent and identically distributed CN (0, 1) random variables.

Since β _mk changes slower than h _mk in several continuous coherence intervals, the β _mk may be treated as a piece wise constant and may be assumed as a known variable.

For example, assuming A _k∈ [0, 1] is the AccThr specific to the UE device k. The network device 140 may initialize AccThrs specific to the respective UE devices, the vector A= [A ₁, A ₂, ... A _K] ^T, to be a set of predefined values, and may determine the vector A= [A ₁, A ₂, ... A _K] ^T to match the system performance in various metrics. For example, the metric may be sum UL/DL throughput maximization, energy efficiency maximization, UE quality of service (QoS) maximization, etc. In order to realize the system performance metric, the network device 140 may refine the values of the vector A= [A ₁, A ₂, ... A _K] ^T by an AccThr allocation operation, until the system performance metric become converged.

The AccThr allocation operation may be performed based on a particle swarm optimization algorithm (e.g., described in J. Kennedy, R. Eberhart. Particle swarm optimization. Proceedings of IEEE International Conference on Neural Networks, Perth, WA, 1995; 1942–1948. ) , a genetic algorithm (e.g., described in "IEE Colloquium on 'Genetic Algorithms for Control Systems Engineering' (Digest No. 1993/130) , " IEE Colloquium on Genetic Algorithms for Control Systems Engineering, 1993, pp. 0_1-. ) , a deep learning algorithm (e.g., described in Li Deng; Dong Yu, Deep Learning: Methods and Applications, now, 2014. ) , etc.

The AccThrs for different UE devices may be different. The determined AccThr 144 is specific to the UE device 110 and may be dynamically adjusted based on the RSQs.

In an embodiment, the AccThr 144 specific to the UE device 110 may be determined further based on pilot sequences assigned for the plurality of UE devices and/or transmitting powers allocated to the plurality of UE devices.

FIG. 2 shows a flow chart illustrating an example procedure for determining AccThrs specific to UE devices according to embodiments of the present disclosure. The example procedure may be performed by the network device 140.

Referring to the FIG. 2, in an operation 210, the network device 140 may initialize the AccThrs to be a set of predefined values.

In an operation 220, the network device 140 may perform a pilot sequence assignment for the plurality of UE devices. The pilot sequence assignment operation may be performed based on a graph coloring (GC) algorithm (e.g., described in H. Liu, J. Zhang, S. Jin and B. Ai, "Graph Coloring Based Pilot Assignment for Cell-Free Massive MIMO Systems, " in IEEE Transactions on Vehicular Technology, vol. 69, no. 8, pp. 9180-9184, Aug. 2020, doi: 10.1109/TVT. 2020.3000496. ) , a tabu-search algorithm (e.g., described in H. Liu, J. Zhang, X. Zhang, A. Kurniawan, T. Juhana and B. Ai, "Tabu-Search-Based Pilot Assignment for Cell-Free Massive MIMO Systems, " in IEEE Transactions on Vehicular Technology, vol. 69, no. 2, pp. 2286-2290, Feb. 2020, doi: 10.1109/TVT. 2019.2956217. ) , a Hungarian algorithm (e.g., described in S. Buzzi, C. D’Andrea, M. Fresia, Y. -P. Zhang and S. Feng, "Pilot Assignment in Cell-Free Massive MIMO Based on the Hungarian Algorithm, " in IEEE Wireless Communications Letters, vol. 10, no. 1, pp. 34-37, Jan. 2021, doi: 10.1109/LWC. 2020.3020003. ) , etc.

In an operation 230, the network device 140 may perform a transmit power allocation for the plurality of UE devices. The transmit power allocation operation may be performed based on a max-min algorithm (e.g., described in H.Q. Ngo, A. Ashikhmin, H. Yang, E.G. Larsson, and T.L. Marzetta, “Cell-free massive MIMO versus small cells, ” IEEE Trans. Wireless Commun., vol. 16, no. 3, pp. 1834–1850, Mar. 2017. ) , a throughput maximization algorithm (S. Buzzi, C. D’Andrea, A. Zappone and C. D’Elia, "User-Centric 5G Cellular Networks: Resource Allocation and Comparison With the Cell-Free Massive MIMO Approach, " in IEEE Transactions on Wireless Communications, vol. 19, no. 2, pp. 1250-1264, Feb. 2020, doi: 10.1109/TWC. 2019.2952117. ) .

In an operation 240, the network device 140 may obtain an original system performance.

In an operation 250, the network device 140 may perform an AccThr allocation, based on, for example, the particle swarm optimization algorithm, the genetic algorithm, the deep learning algorithm, etc.

Then, in an operation 260, the network device 140 may perform the pilot sequence assignment based on, for example, the GC algorithm, the tabu-search algorithm, the Hungarian algorithm, etc. In an operation 270, the network device 140 may perform the transmit power allocation based on, for example, the max-min algorithm, the throughput maximization algorithm, etc.

In an operation 280, the network device 140 may obtain an updated system performance. In an operation 290, the network device 140 may determine whether the system performance is converged. In a case where the system performance is not converged ( “No” prong of the operation 290) , the network device 140 may repeat the procedure from the operation 250. In a case where the system performance is converged ( “Yes” prong of the operation 290) , the network device 140 may determine the current AccThrs as the AccThrs specific to respective UE devices.

Thus, the determined AccThr 144 is specific to the UE device 110 and may be dynamically adjusted based on the RSQs, pilot sequence assignment, and/or transmitting power allocation.

Referring back to the FIG. 1, the network device 140 may transmit the AccThr 144 to the network device 120. In an embodiment, the network device 140 may refrain from transmitting, to the plurality of APs other than the PAP, the AccThr 144. Therefore, an overhead may be saved compared to the case where the network device 140 transmits an AccThr to the plurality of UE devices.

Receiving the AccThr 144, the network device 120 may transmit the AccThr 144 to the UE device 110. The network device 120 does not need to transmit the AccThr 144 to the UE devices other than the UE device 110, and the APs other than the network device 120 do not need to transmit the AccThr 144 to the UE device 110, therefore, the overhead may be saved.

Receiving the AccThr 144, in an operation 160, the UE device 110 may establish a connection with at least one secondary AP (SAP) in the cell free communication system by a RA procedure according to the AccThr 144. For example, the UE device 110 may sort the RSQs related to the plurality of APs and the UE device according to a descending order, and select a set of APs where the ratio of the sum of the RSQs of the set of APs to the sum of the RSQs of the plurality of APs is larger than the AccThr.

is a sorted RSQ vector of the UE device k in a descending order. When

S _k= {1, 2, ... n} may be defined as the serving AP set of the UE device k.

Assuming that the network device 130 is associated with an AP belonging to the S _k= {1, 2, ... n} , the network device 130 may be one of the at least one SAP for the UE device, the UE device 110 may establish a connection with the network device 130 in the operation 160.

FIG. 3 shows a flow chart illustrating an example method 300 for the UE-AP association according to embodiments of the present disclosure. The example method 300 may be performed for example at a UE device in a cell free communication system such as the UE device 110.

Referring to the FIG. 3, the example method 300 may include an operation 310 of establishing a connection with a PAP in the cell free communication system by a RA procedure, and an operation 320 of receiving, from the PAP, an AccThr specific to the UE device.

Details of the operation 310 have been described in the above descriptions with respect to at least the operation 150, and repetitive descriptions thereof are omitted here.

Details of the operation 320 have been described in the above descriptions with respect to at least the AccThr 144, and repetitive descriptions thereof are omitted here.

In an embodiment, the example method 300 may further include an operation of establishing a connection with at least one SAP in the cell free communication system by a RA procedure according to the AccThr. The more details have been described in the above descriptions with respect to at least the operation 160, and repetitive descriptions thereof are omitted here.

In an embodiment, a quality of a DL signal received from the PAP may be higher than a quality of a DL signal received from at least one AP in the cell free communication system other than the PAP. The more details have been described in the above descriptions with respect to at least the operation 112 and the network device 120, and repetitive descriptions thereof are omitted here.

FIG. 4 shows a flow chart illustrating an example method 400 for the UE-AP association according to embodiments of the present disclosure. The example method 400 may be performed for example at a network device in a cell free communication system such as the network device 120.

Referring to the FIG. 4, the example method 400 may include an operation 410 of establishing a connection with a UE device in the cell free communication system, by a RA procedure, an operation 420 of transmitting, to a CPU in the cell free communication system, a quality of an UL signal received from the UE device, an operation 430 of receiving, from the CPU, an AccThr specific to the UE device, and an operation 440 of transmitting, to the UE device, the AccThr.

Details of the operation 410 have been described in the above descriptions with respect to at least the operation 150, and repetitive descriptions thereof are omitted here.

Details of the operation 420 have been described in the above descriptions with respect to at least the RSQ 126, and repetitive descriptions thereof are omitted here.

Details of the operation 430 have been described in the above descriptions with respect to at least the AccThr 144, and repetitive descriptions thereof are omitted here.

Details of the operation 440 have been described in the above descriptions with respect to at least the AccThr 144, and repetitive descriptions thereof are omitted here.

FIG. 5 shows a flow chart illustrating an example method 500 for the UE-AP association according to embodiments of the present disclosure. The example method 500 may be performed for example at a network device in a cell free communication system such as the network device 140.

Referring to the FIG. 5, the example method 500 may include an operation 510 of receiving, from a plurality of APs in the cell free communication system, qualities of UL signals received by respective APs from a plurality of UE devices in the cell free communication system, an operation 520 of determining an AccThr specific to a UE device of the plurality of UE devices based on the qualities of the UP signals, and an operation 530 of transmitting, to a PAP of the UE device among the plurality of APs, the AccThr.

Details of the operation 510 have been described in the above descriptions with respect to at least the RSQ 126 and the RSQ 136, and repetitive descriptions thereof are omitted here.

Details of the operation 420 have been described in the above descriptions with respect to at least the operation 142 and repetitive descriptions thereof are omitted here.

In an embodiment, the AccThr may be determined further based on pilot sequences assigned for the plurality of UE devices and/or transmitting powers allocated to the plurality of UE devices. The more details have been described in the above descriptions with respect to at least the operation 142, and repetitive descriptions thereof are omitted here.

In an embodiment, the example method 500 may further include an operation of refraining from transmitting, to the plurality of APs other than the PAP, the AccThr. The more details have been described in the above descriptions with respect to at least the AccThr 144, and repetitive descriptions thereof are omitted here.

In an embodiment, a quality of a DL signal received by the UE device from the PAP may be higher than a quality of a DL signal received by the UE device from at least one AP of the plurality of APs other than the PAP. The more details have been described in the above descriptions with respect to at least the operation 112 and the network device 120, and repetitive descriptions thereof are omitted here.

FIG. 6 shows a block diagram illustrating an example apparatus 600 for the UE-AP association according to embodiments of the present disclosure. The apparatus, for example, may be at least part of a UE device such as the UE device 110 in the above examples.

As shown in the FIG. 6, the example apparatus 600 may include at least one processor 610 and at least one memory 620 that may include computer program code 630. The at least one memory 620 and the computer program code 630 may be configured to, with the at least one processor 610, cause the apparatus 600 at least to perform the example method 300 described above.

In various example embodiments, the at least one processor 610 in the example apparatus 600 may include, but not limited to, at least one hardware processor, including at least one microprocessor such as a central processing unit (CPU) , a portion of at least one hardware processor, and any other suitable dedicated processor such as those developed based on for example Field Programmable Gate Array (FPGA) and Application Specific Integrated Circuit (ASIC) . Further, the at least one processor 610 may also include at least one other circuitry or element not shown in the FIG. 6.

In various example embodiments, the at least one memory 620 in the example apparatus 600 may include at least one storage medium in various forms, such as a volatile memory and/or a non-volatile memory. The volatile memory may include, but not limited to, for example, a random-access memory (RAM) , a cache, and so on. The non-volatile memory may include, but not limited to, for example, a read only memory (ROM) , a hard disk, a flash memory, and so on. Further, the at least memory 620 may include, but are not limited to, an electric, a magnetic, an optical, an electromagnetic, an infrared, or a semiconductor system, apparatus, or device or any combination of the above.

Further, in various example embodiments, the example apparatus 600 may also include at least one other circuitry, element, and interface, for example at least one I/O interface, at least one antenna element, and the like.

In various example embodiments, the circuitries, parts, elements, and interfaces in the example apparatus 600, including the at least one processor 610 and the at least one memory 620, may be coupled together via any suitable connections including, but not limited to, buses, crossbars, wiring and/or wireless lines, in any suitable ways, for example electrically, magnetically, optically, electromagnetically, and the like.

It is appreciated that the structure of the apparatus on the side of the UE device 110 is not limited to the above example apparatus 600.

FIG. 7 shows a block diagram illustrating an example apparatus 700 for the UE-AP association according to embodiments of the present disclosure. The apparatus, for example, may be at least part of a network device such as the network device 120 in the above examples.

As shown in the FIG. 7, the example apparatus 700 may include at least one processor 710 and at least one memory 720 that may include computer program code 730. The at least one memory 720 and the computer program code 730 may be configured to, with the at least one processor 710, cause the apparatus 700 at least to perform the example method 400 described above.

In various example embodiments, the at least one processor 710 in the example apparatus 700 may include, but not limited to, at least one hardware processor, including at least one microprocessor such as a central processing unit (CPU) , a portion of at least one hardware processor, and any other suitable dedicated processor such as those developed based on for example Field Programmable Gate Array (FPGA) and Application Specific Integrated Circuit (ASIC) . Further, the at least one processor 710 may also include at least one other circuitry or element not shown in the FIG. 7.

In various example embodiments, the at least one memory 720 in the example apparatus 700 may include at least one storage medium in various forms, such as a volatile memory and/or a non-volatile memory. The volatile memory may include, but not limited to, for example, a random-access memory (RAM) , a cache, and so on. The non-volatile memory may include, but not limited to, for example, a read only memory (ROM) , a hard disk, a flash memory, and so on. Further, the at least memory 720 may include, but are not limited to, an electric, a magnetic, an optical, an electromagnetic, an infrared, or a semiconductor system, apparatus, or device or any combination of the above.

Further, in various example embodiments, the example apparatus 700 may also include at least one other circuitry, element, and interface, for example at least one I/O interface, at least one antenna element, and the like.

In various example embodiments, the circuitries, parts, elements, and interfaces in the example apparatus 700, including the at least one processor 710 and the at least one memory 720, may be coupled together via any suitable connections including, but not limited to, buses, crossbars, wiring and/or wireless lines, in any suitable ways, for example electrically, magnetically, optically, electromagnetically, and the like.

It is appreciated that the structure of the apparatus on the side of the network device 120 is not limited to the above example apparatus 700.

FIG. 8 shows a block diagram illustrating an example apparatus 800 for the UE-AP association according to embodiments of the present disclosure. The apparatus, for example, may be at least part of a network device such as the network device 140 in the above examples.

As shown in the FIG. 8, the example apparatus 800 may include at least one processor 810 and at least one memory 820 that may include computer program code 830. The at least one memory 820 and the computer program code 830 may be configured to, with the at least one processor 810, cause the apparatus 800 at least to perform the example method 500 described above.

In various example embodiments, the at least one processor 810 in the example apparatus 800 may include, but not limited to, at least one hardware processor, including at least one microprocessor such as a central processing unit (CPU) , a portion of at least one hardware processor, and any other suitable dedicated processor such as those developed based on for example Field Programmable Gate Array (FPGA) and Application Specific Integrated Circuit (ASIC) . Further, the at least one processor 810 may also include at least one other circuitry or element not shown in the FIG. 8.

In various example embodiments, the at least one memory 820 in the example apparatus 800 may include at least one storage medium in various forms, such as a volatile memory and/or a non-volatile memory. The volatile memory may include, but not limited to, for example, a random-access memory (RAM) , a cache, and so on. The non-volatile memory may include, but not limited to, for example, a read only memory (ROM) , a hard disk, a flash memory, and so on. Further, the at least memory 820 may include, but are not limited to, an electric, a magnetic, an optical, an electromagnetic, an infrared, or a semiconductor system, apparatus, or device or any combination of the above.

Further, in various example embodiments, the example apparatus 800 may also include at least one other circuitry, element, and interface, for example at least one I/O interface, at least one antenna element, and the like.

In various example embodiments, the circuitries, parts, elements, and interfaces in the example apparatus 800, including the at least one processor 810 and the at least one memory 820, may be coupled together via any suitable connections including, but not limited to, buses, crossbars, wiring and/or wireless lines, in any suitable ways, for example electrically, magnetically, optically, electromagnetically, and the like.

It is appreciated that the structure of the apparatus on the side of the network device 140 is not limited to the above example apparatus 800.

FIG. 9 shows a block diagram illustrating an example apparatus 900 for the UE-AP association according to embodiments of the present disclosure. The apparatus, for example, may be at least part of a UE device such as the UE device 110 in the above examples.

As shown in FIG. 9, the example apparatus 900 may include means 910 for performing the operation 310 of the example method 300, and means 920 for performing the operation 320 of the example method 300. In one or more another example embodiments, at least one I/O interface, at least one antenna element, and the like may also be included in the example apparatus 900.

In some example embodiments, examples of means in the example apparatus 900 may include circuitries. For example, an example of means 910 may include a circuitry configured to perform the operation 310 of the example method 300, and an example of means 920 may include a circuitry configured to perform the operation 320 of the example method 300. In some example embodiments, examples of means may also include software modules and any other suitable function entities.

FIG. 10 shows a block diagram illustrating an example apparatus 1000 for the UE-AP association according to embodiments of the present disclosure. The apparatus, for example, may be at least part of a network device such as the network device 120 in the above examples.

As shown in FIG. 10, the example apparatus 1000 may include means 1010 for performing the operation 410 of the example method 400, means 1020 for performing the operation 420 of the example method 400, means 1030 for performing the operation 430 of the example method 400, and means 1040 for performing the operation 440 of the example method 400. In one or more another example embodiments, at least one I/O interface, at least one antenna element, and the like may also be included in the example apparatus 1000.

In some example embodiments, examples of means in the example apparatus 1000 may include circuitries. For example, an example of means 1010 may include a circuitry configured to perform the operation 410 of the example method 400, an example of means 1020 may include a circuitry configured to perform the operation 420 of the example method 400, an example of means 1030 may include a circuitry configured to perform the operation 430 of the example method 400, and an example of means 1040 may include a circuitry configured to perform the operation 440 of the example method 400. In some example embodiments, examples of means may also include software modules and any other suitable function entities.

FIG. 11 shows a block diagram illustrating an example apparatus 1100 for the UE-AP association according to embodiments of the present disclosure. The apparatus, for example, may be at least part of a network device such as the network device 140 in the above examples.

As shown in FIG. 11, the example apparatus 1100 may include means 1110 for performing the operation 510 of the example method 500, means 1120 for performing the operation 520 of the example method 500, and means 1130 for performing the operation 530 of the example method 500. In one or more another example embodiments, at least one I/O interface, at least one antenna element, and the like may also be included in the example apparatus 1100.

In some example embodiments, examples of means in the example apparatus 1100 may include circuitries. For example, an example of means 1110 may include a circuitry configured to perform the operation 510 of the example method 500, an example of means 1120 may include a circuitry configured to perform the operation 520 of the example method 500, and an example of means 1130 may include a circuitry configured to perform the operation 530 of the example method 500. In some example embodiments, examples of means may also include software modules and any other suitable function entities.

The term “circuitry” throughout this disclosure may refer to one or more or all of the following: (a) hardware-only circuit implementations (such as implementations in only analog and/or digital circuitry) ; (b) combinations of hardware circuits and software, such as (as applicable) (i) a combination of analog and/or digital hardware circuit (s) with software/firmware and (ii) any portions of hardware processor (s) with software (including digital signal processor (s) ) , software, and memory (ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions) ; and (c) hardware circuit (s) and or processor (s) , such as a microprocessor (s) or a portion of a microprocessor (s) , that requires software (e.g., firmware) for operation, but the software may not be present when it is not needed for operation. This definition of circuitry applies to one or all uses of this term in this disclosure, including in any claims. As a further example, as used in this disclosure, the term circuitry also covers an implementation of merely a hardware circuit or processor (or multiple processors) or portion of a hardware circuit or processor and its (or their) accompanying software and/or firmware. The term circuitry also covers, for example and if applicable to the claim element, a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in server, a cellular network device, or other computing or network device.

Another example embodiment may relate to computer program codes or instructions which may cause an apparatus to perform at least respective methods described above. Another example embodiment may be related to a computer readable medium having such computer program codes or instructions stored thereon. In some embodiments, such a computer readable medium may include at least one storage medium in various forms such as a volatile memory and/or a non-volatile memory. The volatile memory may include, but not limited to, for example, a RAM, a cache, and so on. The non-volatile memory may include, but not limited to, a ROM, a hard disk, a flash memory, and so on. The non-volatile memory may also include, but are not limited to, an electric, a magnetic, an optical, an electromagnetic, an infrared, or a semiconductor system, apparatus, or device or any combination of the above.

Unless the context clearly requires otherwise, throughout the description and the claims, the words “comprise, ” “comprising, ” and the like are to be construed in an inclusive sense, as opposed to an exclusive or exhaustive sense; that is to say, in the sense of “including, but not limited to. ” The word “coupled” , as generally used herein, refers to two or more elements that may be either directly connected, or connected by way of one or more intermediate elements. Likewise, the word “connected” , as generally used herein, refers to two or more elements that may be either directly connected, or connected by way of one or more intermediate elements. Additionally, the words “herein, ” “above, ” “below, ” and words of similar import, when used in this application, shall refer to this application as a whole and not to any particular portions of this application. Where the context permits, words in the description using the singular or plural number may also include the plural or singular number respectively. The word “or” in reference to a list of two or more items, that word covers all of the following interpretations of the word: any of the items in the list, all of the items in the list, and any combination of the items in the list.

Moreover, conditional language used herein, such as, among others, “can, ” “could, ” “might, ” “may, ” “e.g., ” “for example, ” “such as” and the like, unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain embodiments include, while other embodiments do not include, certain features, elements and/or states. Thus, such conditional language is not generally intended to imply that features, elements and/or states are in any way required for one or more embodiments or that one or more embodiments necessarily include logic for deciding, with or without author input or prompting, whether these features, elements and/or states are included or are to be performed in any particular embodiment.

As used herein, the term "determine/determining" (and grammatical variants thereof) can include, not least: calculating, computing, processing, deriving, measuring, investigating, looking up (for example, looking up in a table, a database or another data structure) , ascertaining and the like. Also, "determining" can include receiving (for example, receiving information) , accessing (for example, accessing data in a memory) , obtaining and the like. Also, "determine/determining" can include resolving, selecting, choosing, establishing, and the like.

While some embodiments have been described, these embodiments have been presented by way of example, and are not intended to limit the scope of the disclosure. Indeed, the apparatus, methods, and systems described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the methods and systems described herein may be made without departing from the spirit of the disclosure. For example, while blocks are presented in a given arrangement, alternative embodiments may perform similar functionalities with different components and/or circuit topologies, and some blocks may be deleted, moved, added, subdivided, combined, and/or modified. At least one of these blocks may be implemented in a variety of different ways. The order of these blocks may also be changed. Any suitable combination of the elements and actions of the some embodiments described above can be combined to provide further embodiments. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the disclosure.

Abbreviations used in the description and/or in the figures are defined as follows:

AccThr accessing threshold

AP access point

CPU central processing unit

CRS cell-specific reference signal

DL downlink

GC graph coloring

MIMO multiple-input multiple-output

RSQ received signal quality

RSRP reference signal received power

PAP primary AP

PBCH physical broadcast channel

QoS quality of service

RA random access

SAP secondary AP

SINR signal to interference plus noise ratio

SNR signal to noise ratio

SRS sounding reference signal

UE user equipment

UL uplink

Claims

An apparatus comprising:

at least one processor; and

at least one memory comprising computer program code, the at least one memory and the computer program code being configured to, with the at least one processor, cause the apparatus as a user equipment device in a cell free communication system to perform:

establishing a connection with a primary access point in the cell free communication system by a random access procedure; and

receiving, from the primary access point, an accessing threshold specific to the user equipment device.
The apparatus of claim 1, wherein the at least one memory and the computer program code are further configured to, with the at least one processor, cause the apparatus to further perform:

establishing a connection with at least one secondary access point in the cell free communication system by a random access procedure according to the accessing threshold.
The apparatus of claim 1 or 2, wherein a quality of a downlink signal received from the primary access point is higher than a quality of a downlink signal received from at least one access point in the cell free communication system other than the primary access point.
An apparatus comprising:

at least one processor; and

at least one memory comprising computer program code, the at least one memory and the computer program code being configured to, with the at least one processor, cause the apparatus as a network device associated with an access point in a cell free communication system to perform:

establishing a connection with a user equipment device in the cell free communication system, by a random access procedure;

transmitting, to a central processing unit in the cell free communication system, a quality of an uplink signal received from the user equipment device;

receiving, from the central processing unit, an accessing threshold specific to the user equipment device; and

transmitting, to the user equipment device, the accessing threshold.
An apparatus comprising:

at least one processor; and

at least one memory comprising computer program code, the at least one memory and the computer program code being configured to, with the at least one processor, cause the apparatus as a network device associated with a central processing unit in a cell free communication system to perform:

receiving, from a plurality of access points in the cell free communication system, qualities of uplink signals received by respective access points from a plurality of user equipment devices in the cell free communication system;

determining an accessing threshold specific to a user equipment device of the plurality of user equipment devices based on the qualities of the uplink signals; and

transmitting, to a primary access point of the user equipment device among the plurality of access points, the accessing threshold.
The apparatus of claim 5, wherein the accessing threshold is determined further based on pilot sequences assigned for the plurality of user equipment devices and/or transmitting powers allocated to the plurality of user equipment devices.
The apparatus of claim 5 or 6, wherein the at least one memory and the computer program code are further configured to, with the at least one processor, cause the apparatus to further perform:

refraining from transmitting, to the plurality of access points other than the primary access point, the accessing threshold.
The apparatus of any of claims 5 to 7, wherein a quality of a downlink signal received by the user equipment device from the primary access point is higher than a quality of a downlink signal received by the user equipment device from at least one access point of the plurality of access points other than the primary access point.
A method performed by a user equipment device in a cell free communication system comprising:

establishing a connection with a primary access point in the cell free communication system by a random access procedure; and

receiving, from the primary access point, an accessing threshold specific to the user equipment device.
The method of claim 9, further comprising:

establishing a connection with at least one secondary access point in the cell free communication system by a random access procedure according to the accessing threshold.
The method of claim 9 or 10, wherein a quality of a downlink signal received from the primary access point is higher than a quality of a downlink signal received from at least one access point in the cell free communication system other than the primary access point.
A method performed by a network device associated with an access point in a cell free communication system comprising:

establishing a connection with a user equipment device in the cell free communication system, by a random access procedure;

transmitting, to a central processing unit in the cell free communication system, a quality of an uplink signal received from the user equipment device;

receiving, from the central processing unit, an accessing threshold specific to the user equipment device; and

transmitting, to the user equipment device, the accessing threshold.
A method performed by a network device associated with a central processing unit in a cell free communication system comprising:

receiving, from a plurality of access points in the cell free communication system, qualities of uplink signals received by respective access points from a plurality of user equipment devices in the cell free communication system;

determining an accessing threshold specific to a user equipment device of the plurality of user equipment devices based on the qualities of the uplink signals; and

transmitting, to a primary access point of the user equipment device among the plurality of access points, the accessing threshold.
The method of claim 13, wherein the accessing threshold is determined further based on pilot sequences assigned for the plurality of user equipment devices and/or transmitting powers allocated to the plurality of user equipment devices.
The method of claim 13 or 14, further comprising:

refraining from transmitting, to the plurality of access points other than the primary access point, the accessing threshold.
The method of any of claims 13 to 15, wherein a quality of a downlink signal received by the user equipment device from the primary access point is higher than a quality of a downlink signal received by the user equipment device from at least one access point of the plurality of access points other than the primary access point.
An apparatus as a user equipment device in a cell free communication system comprising:

means for establishing a connection with a primary access point in the cell free communication system by a random access procedure; and

means for receiving, from the primary access point, an accessing threshold specific to the user equipment device.
An apparatus as a network device associated with an access point in a cell free communication system comprising:

means for establishing a connection with a user equipment device in the cell free communication system, by a random access procedure;

means for transmitting, to a central processing unit in the cell free communication system, a quality of an uplink signal received from the user equipment device;

means for receiving, from the central processing unit, an accessing threshold specific to the user equipment device; and

means for transmitting, to the user equipment device, the accessing threshold.
An apparatus as a network device associated with a central processing unit in a cell free communication system comprising:

means for receiving, from a plurality of access points in the cell free communication system, qualities of uplink signals received by respective access points from a plurality of user equipment devices in the cell free communication system;

means for determining an accessing threshold specific to a user equipment device of the plurality of user equipment devices based on the qualities of the uplink signals; and

means for transmitting, to a primary access point of the user equipment device among the plurality of access points, the accessing threshold.
A computer readable medium comprising program instructions for causing an apparatus as a user equipment device in a cell free communication system to perform:

establishing a connection with a primary access point in the cell free communication system by a random access procedure; and

receiving, from the primary access point, an accessing threshold specific to the user equipment device.
A computer readable medium comprising program instructions for causing an apparatus as a network device associated with an access point in a cell free communication system comprising:

establishing a connection with a user equipment device in the cell free communication system, by a random access procedure;

transmitting, to a central processing unit in the cell free communication system, a quality of an uplink signal received from the user equipment device;

receiving, from the central processing unit, an accessing threshold specific to the user equipment device; and

transmitting, to the user equipment device, the accessing threshold.
A computer readable medium comprising program instructions for causing an apparatus as a network device associated with a central processing unit in a cell free communication system comprising:

receiving, from a plurality of access points in the cell free communication system, qualities of uplink signals received by respective access points from a plurality of user equipment devices in the cell free communication system;

determining an accessing threshold specific to a user equipment device of the plurality of user equipment devices based on the qualities of the uplink signals; and

transmitting, to a primary access point of the user equipment device among the plurality of access points, the accessing threshold.