Methods of determining coverage areas

Generally, a wireless network is divided into cells, each cell having at least one base station. A user device (eg, a mobile phone) wishing to transmit information establishes communication with a base station in the cell.

In addition to the identification parameters, the operating parameters are part of network management. Various operating parameters such as antenna orientation (eg, tilt angle), transmit power limits, and pilot power ratios affect network functionality.

In 3rd generation (3G) standards for wireless networks such as CDMA2000 and Universal Mobile Telecommunications Systems (UMTS), profiling is used to evaluate the general behavior of network algorithms. For performance analysis in 3G, such as handoff, access performance, and application throughput analysis, a hexagonal network model of communicable area is used.

Figure 1 illustrates a traditional hexagonal network model. Figure 1 shows the traditional hexagonal network model 100. As shown in the figure, the hexagonal network model 100 includes base stations BS1 to BS7, and each of the base stations BS1 to BS7 has a communicable area C1 to C7. As shown in the figure, the communicable areas C1 to C7 are cells for base stations BS1 to BS7 and are modeled as hexagons. The hexagonal network model is sufficient for 3G technology.

Long Term Evolution (LTE) is the name given to projects that improve the Universal Mobile Telecommunications Systems (UMTS) standard to address future requirements. In one aspect, UMTS has been modified to provide an advanced universal terrestrial radio access network (E-UTRAN) as a 4th generation (4G) radio network.

E-UTRAN is an advanced NodeB (eNodeB) that provides UEs with advanced universal terrestrial radio access (E-UTRA) user plane (PDCP / RLC / MAC / PHY) and control plane (RRC) protocol terminals. including. As described herein, eNodeB means a base station that provides wireless access to a user device (UE) within a given communicable area. This communicable area is called the cell footprint. eNodeB interconnects with each other via the X2 interface. The eNodeB also connects to the mobility management entity (MME) via the S1-MME interface (control plane) and to the serving gateway (SGW) via the S1-U interface (user / data plane).

In 4G, performance has become more personal and localized with a self-organizing and self-optimizing network (SON). Therefore, performance analysis evaluation becomes more accountable, and it is necessary to answer specific questions about specific cells. As a result, general analysis of networks using the hexagonal model is not sufficient. In addition, because performance optimization is part of the network, the analysis and model should provide computational efficiency to allow these computations to be made on the network components.

<p num="0008"><nplcit num="1"><text>3GPP TS 36.300 V.8.6.0</text></nplcit></p>

At least one exemplary embodiment discloses a method of determining a communicable area within a communication system. The method comprises determining a plurality of base stations in a communication system by a controller, and determining a Voronoi region for each of the plurality of base stations by a controller. The Voronoi area corresponds to the communicable area for the base station.

At least another exemplary embodiment discloses a method of analyzing the performance of a communication system. The method comprises determining at least one vertex of the Voronoi region by a base station containing at least one antenna. The Voronoi region corresponds to the communicable area for the base station, and at least one vertex corresponds to the maximum transmission distance.

An exemplary embodiment will be clearly understood from the detailed description below in conjunction with the accompanying drawings. As described herein, FIGS. 1-6 represent non-limiting exemplary embodiments.

<figref num="1">It is a figure which shows the conventional hexagonal network model.</figref><figref num="2">It is a figure which shows a part of the communication system by an exemplary embodiment.</figref><figref num="3">It is a figure which shows the method of determining the communicable area in a communication system by an exemplary embodiment.</figref><figref num="4">It is a figure which shows the method of determining the transmission power based on a Voronoi region by an exemplary embodiment.</figref><figref num="5">It is a figure which shows the method of determining the tilt angle for an antenna based on a Voronoi region by an exemplary embodiment.</figref><figref num="6">It is a figure which shows the communication system which has a plurality of eNodeB and Voronoi region by an exemplary embodiment.</figref>

Here, various exemplary embodiments will be described in more detail with reference to the accompanying drawings in which some exemplary embodiments are illustrated. In the drawings, the hierarchy and area thickness may be exaggerated for clarity.

Accordingly, the exemplary embodiments are capable of various modified and alternative embodiments, of which the embodiments are shown in the drawings as examples and will be described in detail herein. However, the exemplary embodiments are not limited to the specific embodiments disclosed, whereas the exemplary embodiments are all modifications, equivalents, and alternatives within the scope of the claims. It should be understood that it includes things as objects. Throughout the description of the figure, the same numbers represent the same components.

Although terms such as first and second may be used herein to describe the various components, it will be understood that these components should not be limited by these terms. .. These terms are only used to distinguish one component from another. Without departing from the scope of the exemplary embodiment, for example, the first component may be referred to as the second component, and similarly, the second component may be referred to as the first component. Can be done. As used herein, the term "and / or" includes any combination of one or more related listed items.

The terminology used herein is for the purpose of describing only specific embodiments and is not intended to limit exemplary embodiments. As used herein, the singular forms "a", "an" and "the" also include the plural, unless the context clearly indicates otherwise. In addition, the terms "provide," "provide," "include," and / or "include," as used herein, are described features, integers, steps, actions, components and /. Or it will be appreciated that it specifies the existence of a component, but does not preclude the existence or addition of one or more other features, integers, steps, behaviors, components, components, and / or groups thereof.

It should also be noted that in some alternative implementations, the noted features / behaviors can occur outside the numerically noted order. For example, two numbers shown in succession may actually be executed at substantially the same time, or sometimes in reverse order, depending on the function / action involved.

Unless otherwise defined, all terms used herein (including technical and scientific terms) shall be generally understood by those skilled in the art to which the exemplary embodiments belong. Has the same meaning. Further, for example, terms defined in commonly used dictionaries should be construed to have meanings consistent with their meanings in the context of the relevant technology, as expressly herein. It will be understood that unless defined, it is not interpreted in an idealized or overcoated formal sense.

The algorithm is considered to be a coherent sequence of steps leading to the desired result, as the term is used herein and as is commonly used. A step is a step that requires a physical manipulation of a physical quantity. In general, but not necessarily, these quantities take the form of optical, electrical, or magnetic signals that can be stored, transferred, coupled, compared, and otherwise manipulated. .. It has sometimes proved convenient to refer to these signals as bits, values, elements, signs, letters, terms, numbers, etc., mainly for common use reasons.

In the description below, it can be implemented as a program module or functional process that contains routines, programs, objects, components, data structures, etc. that perform a particular task or implement a particular abstract data type, or already exist. Behavioral behaviors and code representations (eg, in the form of a flow diagram) that can be implemented using existing hardware at a network component or control node (eg, a scheduler located at a cell site, base station, or Node B). An exemplary embodiment will be described with reference to.

Unless otherwise described in detail, or as the description makes clear, terms such as "processing" or "arithmetic" or "calculation" or "decision" or "display" are internal to the registers and memory of a computer system. Manipulating data expressed as physical and electrical quantities, as well as physical quantities inside a computer system memory or register, or other device that stores, transmits, or displays such information. It means the operation and processing of a computer system or similar electronic computing device that converts it into other data.

As used herein, the term "user device" (UE) can be synonymous with mobile user, mobile station, mobile terminal, user, subscriber, wireless terminal and / or remote station and within a wireless communication network. Can represent remote users of wireless resources.

The term "evolved NodeB" can be understood as one or more cell sites, NodeBs, base stations, access points and / or any terminal for radio frequency communication. The exemplary embodiments described below may generally be applicable to network architectures such as LTE, ad hoc and / or mesh network architectures.

Voronoi division is well known in mathematics. The Voronoi division includes multiple Voronoi regions. Each Voronoi region contains a mother point. Each point in the Voronoi region is closer to the mother point of the Voronoi region than any other mother point of the other Voronoi region. A segment (boundary) of a Voronoi region is all points equidistant from the base point of that Voronoi region and the base point of another Voronoi region.

An exemplary embodiment discloses a method of determining a Voronoi region for each eNodeB (base station) in a communication system. The Voronoi area determined for each eNodeB is used as a communicable area for eNodeB by the controller of the communication system. eNodeB is the mother point of the Voronoi region. Since the communicable area is based on the associated Voronoi area, every location in the communicable area is closest to the eNodeB associated with the communicable area.

Figure 2 shows part of an E-UTRAN deployment that includes a network management layer 200 that communicates with multiple eNodeB 205s. As is well known, multiple cells or a single cell are often associated with a single eNodeB.

The network management layer 200 of E-UTRAN includes the mobility management entity (MME) 210 and the serving gateway SGW212. The MME210 is a logical entity that controls the eNodeB 205 and coordinates scheduling and transmission for the eNodeB 205. More specifically, MME210's features include scheduling and timing control, eNodeB registration, and feedback. The MME210 communicates bidirectionally with the eNodeB 205. As described in 3GPP TS 36.300 V.8.6.0, the entire contents of which are incorporated herein by reference, the MME210 is, among other things, user radio access network (RAN) mobility management procedures and users. -Control the session management procedure.

For example, the MME210 controls UE tracking and reachability. The MME210 also sends signal messages such as a paging message to inform the destination UE of an upcoming connection request (for example, when the UE is called or when data for the UE at network boot comes) and / Or control and execute retransmission.

SGW212 is a component of the data plane. The SGW212 is a mobility anchor during a handoff between eNodeB 205 and a mobility anchor between LTE and other 3GPP technologies.

Although exemplary embodiments have been described with reference to 4G / LTE networks, it is considered that the exemplary embodiments are applicable to any wireless communication infrastructure.

FIG. 3 shows a method of determining a communicable area in a communication system. The method of Figure 3 can be performed by a controller within the network management layer, such as the MME210 within the network management layer 200. More specifically, the controller implementing the method of FIG. 3 determines a plurality of base stations in the communication system and determines the Voronoi region for each of the plurality of eNodeBs. The Voronoi area corresponds to the communicable area for eNodeB.

In step S300, the controller determines the number of multiple eNodeBs (base stations) in the communication system. The controller can determine the number of eNodeBs by any known method. The controller can set a limit on the number of eNodeBs.

In step S310, the controller then determines the Voronoi region (cell footprint) for each of the plurality of eNodeBs. More specifically, the controller determines a Voronoi partition that includes a Voronoi region for a cell site (eg, a radio access network) within a communication system. The controller determines the Voronoi region by using the associated eNodeB as the base point for the Voronoi region.

The algorithms used to determine the Voronoi division are known in areas not related to communications. However, the controller can use the Voronoi division and any known algorithm used to determine the Voronoi region within the Voronoi division.

For example, the controller can determine the Voronoi region by assuming a planar world diagram. The controller can use the Fortune algorithm to determine the Voronoi region of the eNodeB using the location of the eNodeB in the Fortune algorithm (eg, the X and Y coordinates).

When the controller determines the Voronoi division, in step S320, the controller sets the communicable area for eNodeB based on the related Voronoi area. The communicable area used for performance analysis related to eNodeB is the related Voronoi area for eNodeB. Since the communicable area is based on the associated Voronoi area, every location within the communicable area is closest to the eNodeB associated with the communicable area.

The controller is configured to send a signal indicating the associated Voronoi region to each eNodeB. In addition, each eNodeB sets initial parameter values based on the associated Voronoi region. For example, the controller can assume a planar world diagram and determine the Voronoi region based on the planar world diagram. The Voronoi region is used by the controller to determine the initial parameter values. Initial parameter values are stored in each cell and improved based on UE measurements. Initial parameter values may include signal power, power deviation for traffic and control channels, antenna tilt angle, handoff parameters, and reselection parameters.

Therefore, in the performance analysis, the communicable area for eNodeB is not a hexagon. On the contrary, the communicable region according to the exemplary embodiment is a convex polygon (Voronoi region).

Due to natural radio propagation (decrease in reception level due to distance from the transmitter), the Voronoi region offers many advantages over traditional hexagonal models.

Two such examples are antenna tilt and transmit power. The transmit power of eNodeB is associated with one of the vertices of the Voronoi region.

FIG. 4 shows a method of determining the transmission power based on the Voronoi region. Figure 5 shows how to determine the tilt angle for an antenna on an eNodeB based on the Voronoi region. FIG. 6 shows a communication system having a plurality of eNodeBs and a Voronoi region as a communicable area. FIG. 6 is used to illustrate the methods shown in FIGS. 4 and 5. The method shown in FIGS. 4 and 5 can be implemented by eNodeB in a communication system such as eNodeB 205 shown in FIG.

Figures 4 and 5 are implemented by an eNodeB in communication with a controller configured to determine the Voronoi region for the communicable area. eNodeB contains at least one antenna.

In step S400, the eNodeB determines the relevant Voronoi region for the eNodeB. More specifically, the eNodeB receives a signal from the controller indicating the Voronoi region. Using Figure 2 as an example, eNodeB receives a signal from the MME 210 indicating the Voronoi region. The eNodeB also determines at least one vertex in the associated Voronoi region (eg, the vertex farthest from the location of the eNodeB). At least one vertex is the maximum distance d from eNodeB within the associated Voronoi region_maxCan be in.

Then eNodeB in step S410, maximum distance d_maxThe transmission power for the communicable area is determined based on. The transmit power is determined by eNodeB so that all UEs in the communicable region (Voronoi region) can receive the signal transmitted by eNodeB. In step S420, the eNodeB transmits a signal to the UE in the communicable area for the eNodeB with its transmission power.

As described, eNodeB at least one top of first Voronoi region to determine the point. The Voronoi region corresponds to the communicable region for eNodeB, and at least one vertex corresponds to the maximum transmission distance. As a result, the eNodeB receives the Voronoi region determined from the controller.

FIG. 5 shows how to determine the tilt angle for the antenna based on the Voronoi region. Step S500 is the same as step S400. Therefore, for the sake of brevity, no detailed description of step S500 is provided.

In step S510, eNodeB has the maximum distance d_maxAnd the tilt angle for the antenna is determined based on the height h of the antenna. The determination of the tilt angle will be described in more detail with reference to FIG.

When eNodeB determines the tilt angle of the antenna, in step S520, eNodeB transmits a signal at that tilt angle. Although the described eNodeB includes one antenna, it should be understood that exemplary embodiments can include an eNodeB with multiple antennas. For example, exemplary embodiments can be implemented in multi-input multi-output (MIMO) systems.

For example, each time the controller detects that eNodeB is inactive (eg, shutting down) or has been added to the communication system, each of FIGS. 3-5 can be performed by the controller and eNodeB. If the eNodeB goes down, the controller reconfigures the Voronoi region for each active eNodeB. Therefore, the communicable area for the active eNodeB should compensate for the communicable area lost due to the inactive eNodeB.

FIG. 6 shows a communication system having a plurality of eNodeBs and a Voronoi region as a communicable area. As shown in the figure, the communication system 600 is eNodeB EN₁~ EN₁₀including. Each eNodeB EN₁~ EN₁₀Is the communicable area CA₁~ CA₁₀is connected with. Although not shown, it should be understood that the communication system 600 includes a controller such as the MME210. As described in the method of Figure 3, the controller is a communicable area CA₁~ CA₁₀To decide.

For the sake of clarity and brevity, eNodeB EN₁And eNodeB EN₁Communicable area CA for₁Will be explained. However, eNodeB EN₁The explanation is eNodeB EN₂~ EN₁₀It should be understood that it is applicable to. Further, while communication system 600 is shown to have 10 eNodeBs, communication system 600 can include more than 10 eNodeBs or less than 10 eNodeBs, an exemplary embodiment being in 10 eNodeBs. It should not be interpreted as limited.

As shown in the figure, eNodeB EN₁Is the communicable area CA₁Antenna A configured to send and receive signals to and from the UE and controller inside₁including. Antenna A₁Is placed at the height of h above the ground.

ENodeB EN based on the signal received from the controller₁Is its related Voronoi area (step S400 / S500), communicable area CA₁Determine the apex of. Communicable area CA₁Voronoi region for is vertex V₁~ V₅including. Vertex V as shown₅Is eNodeB EN₁Maximum distance from d_maxIt is in. eNodeB EN₁The transmission power determined by eNodeB EN₁Communicatable area CA from₁Maximum distance to the edge of_maxSince it is based on, the communicable area CA₁Each UE in the eNodeB EN with its transmission power₁Receives the signal transmitted by.

eNodeB EN₁Determines the transmit power using the following formula.

<maths num="1"><img id="000002" he="19" wi="145" file="JP5709983B2_D0001.tif" img-format="tif" img-content="drawing" /></maths>Here P₁Is eNodeB EN₁Distance from d_maxIt is the power reception level at the point in. eNodeB EN₁Transmission power for T₀And α is an attenuation constant based on the operating frequency band.

Also, the communicable area CA₁Is eNodeB EN₁Based on the sector configuration for eNodeB EN₁Includes points S1 to S3 determined by.

In addition, eNodeB EN₁Determines the tilt of the antenna as follows. Inclination = tan^-1(h / d_max) (2)

UE is eNodeB EN₁When communicating with, the actual UE measurement can provide a more accurate estimate of maximum path loss than the maximum path loss based on the attenuation constant α. The difference between the maximum path loss based on the attenuation constant α and the maximum path loss based on the UE measurement is eNodeB EN to update the compensation power amount of the transmit power as well as the power estimate of the load distribution.₁Used by.

For convenience, exemplary embodiments have been described with each base station / eNodeB including all cells. However, exemplary embodiments can be extended to any number of sectors / cells.

Although the exemplary embodiments have been described in this way, it will be clear that the aforementioned embodiments can be modified in many ways. Such variants are not considered to deviate from the spirit and scope of the exemplary embodiments, and all such modifications may be within the scope of the claims. It should be obvious to those skilled in the art.