WO2015152931A1

WO2015152931A1 - Method of operating vertical sectorization in fd-mimo systems

Info

Publication number: WO2015152931A1
Application number: PCT/US2014/032887
Authority: WO
Inventors: Salam Akoum; Joydeep Acharya; Amitav Mukherjee
Original assignee: Hitachi, Ltd.
Priority date: 2014-04-03
Filing date: 2014-04-03
Publication date: 2015-10-08

Abstract

Example implementations described herein are directed to forming additional sectors in the vertical domain (called vertical sectorization) for a base station (BS). Example implementations may involve various methods of forming and operating vertical sectors. Example implementations may involve a BS configured with a two dimensional active antenna grid such as in a Full Dimensional Multiple Input Multiple Output (FD-MIMO) system. Example implementations may allow a network operator to create vertical sectors, perform initial configuration and optimize the subsequent data rate performance.

Description

METHOD OF OPERATING VERTICAL SECTORIZATION IN FD-MIMO

SYSTEMS

BACKGROUND

Field

[001] Example implementations described herein are directed to wireless systems, and more specifically, to vertical sectorization in Full Dimension Multiple Input Multiple Output (FD-MIMO) systems.

Related art

[002] Consider a base station located at the origin of the spherical coordinate system as shown in FIG. 1. The transmit energy of the base station is contained within a three dimensional spatial region called a sector. This is mathematically expressed in terms of the antenna array response Α(φ, Θ) where φ and Θ are the azimuth and elevation angles of the location of the user equipment (UE). The antenna array response of the sector Α(φ, θ) is characterized by two parameters depending on the number of antenna elements that form the antenna array, and the antenna spacing between the elements of the array, as well as the type of the array (e.g. Uniform Planar Array - UP A, Uniform Linear Array- ULA, Uniform Circular Array - UCA, etc).

[003] Orientation or tilt: The direction of the maximum radiated signal energy. Also called the boresight as illustrated in FIG. 1. Note that boresight Θ varies from 0 to 180 degrees with 0 being the zenith direction. Sectors with tilt values of Θ < 90 are oriented upward and sectors with tilt values 90 < Θ < 180 are oriented downward.

[004] Half power beam width (HPBW): This is the angular separation between the two points where the radiation pattern achieves its half-power (-3dB) relative to the maximum value of the pattern. The HPBW can be an indication of the sector beam width. A sector with large HPBW covers a larger region.

[005] A UE at a distance d from the base station will observe a received power proportional to ΡΑ(φ, θ)0(ά) where P is the transmit power and G(d) is the large scale channel fading (path loss, shadowing etc.) at distance d .

[006] FIGS. 2(a) and 2(b) illustrate a base station system in the related art. The three dimensional view is illustrated in FIG. 2(a) and the two dimensional view in the azimuth is illustrated in FIG. 2(b). Each base station or enhanced node B (eNodeB) has three co- located sectors with their boresight, for example separated by 120 degrees in the azimuth

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DOCS 120179-HIT020/1945344.1 domain for the case of three sectors, and each of them having the same boresight in the zenith domain. The boresight in the zenith domain is also called the vertical tilt.

[007] The sector parameters (tilts and HPBWs) are chosen so that each has the same coverage pattern in the entire azimuth plane (0 to 360 degrees). This is because the long term average user distribution (over all possible cellular deployments over a long time) is uniform. There may be local non-uniformity in UE deployments (e.g. such as a hot-spot), which can be targeted by adding extra base stations or access points for coverage enhancement (small cells). However, related art implementations maintain uniformity among the the macro cell horizontal sectors.

[008] In the related art, it may be possible to utilize vertical sectors where the base station can form additional sectors by choosing different tilts in the zenith domain. An example is illustrated in FIG. 3. There are multiple applications of vertical sectorization. For example, the network capacity may be increased by increasing the number of users to be served simultaneously through dividing the horizontal sector into multiple sectors (inner and outer sector for the case of two vertical sectors). Another application is to target users that may be located on top floors of a high-rise building, through serving them with a dedicated beam or vertical sector. In the related art implementations of vertical sectorization, user distribution is not considered when forming vertical sectors. The vertical sectors are formed such that the area is divided uniformly among different sectors. Furthermore the distribution of the users in the vertical or zenith direction is not considered when forming the sectors or allocating the available resources at the base station site among different sectors.

Summary of the Invention

[009] Aspects of the present disclosure include a base station, which may involve a transmission array configured to create one or more vertical sectors to transmit to one or more user equipment (UE) served by the base station based on one or more parameters of the one or more vertical sectors; a memory configured to store a distribution of elevation angles of the one or more user equipment (UE) served by the base station; and a processor configured to calculate the one or more parameters of the one or more vertical sectors based on the distribution of elevation angles of the one or more UE served by the base station.

[010] Aspects of the present disclosure include a method, which may involve managing a distribution of elevation angles of one or more user equipment (UE) served by a base station; calculating one or more parameters of the one or more vertical sectors based on

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DOCS 120179-HIT020/1945344.1 the distribution of elevation angles of the one or more UE served by the base station; and creating the one or more vertical sectors to transmit to one or more user equipment (UE) served by the base station based on the one or more parameters of the one or more vertical sectors.

[Oi l] Aspects of the present disclosure include a non-transitory computer readable medium storing instructions for executing a process. The instructions may involve managing a distribution of elevation angles of one or more user equipment (UE) served by a base station; calculating one or more parameters of the one or more vertical sectors based on the distribution of elevation angles of the one or more UE served by the base station; and creating the one or more vertical sectors to transmit to one or more user equipment (UE) served by the base station based on the one or more parameters of the one or more vertical sectors.

Brief Description of Drawings

[012] FIG. 1 illustrates a spherical coordinate system with a base station at the origin and a transmitted sector beam.

[013] FIGS. 2(a) and 2(b) illustrate a base station with three horizontal sectors with a common vertical tilt.

[014] FIG. 3 illustrates a base station system with an additional vertical sector that has uptilt to a building.

[015] FIG. 4(a) illustrates a block diagram for a base station, in accordance with an example implementation.

[016] FIG. 4(b) illustrates example modules at the base station for configuring the vertical sectors in accordance with example implementations.

[017] FIG. 5 illustrates an example flow diagram for the information collection, in accordance with an example implementation.

[018] FIG. 6 illustrates a relationship of the elevation angle with two dimensional distance and user height, in accordance with an example implementation.

[019] FIG. 7 illustrates a probability distribution function of the elevation angles of users for different parameters of building density, in accordance with an example implementation.

[020] FIG. 8 illustrates different vertical sectors with increasing tilts, in accordance with an example implementation.

[021] FIG. 9 illustrates a cost function optimization module, in accordance with an example implementation.

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DOCS 120179-HIT020/1945344.1 [022] FIG. 10 illustrates how the channel characteristics may vary depending on the vertical sector tilt, in accordance with an example implementation.

[023] FIG. 1 1 illustrates a variation of Line of Sight probability with UE height, in accordance with an example implementation.

Detailed Description

[024] The following detailed description provides further details of the figures and example implementations of the present application. Reference numerals and descriptions of redundant elements between figures are omitted for clarity. Terms used throughout the description are provided as examples and are not intended to be limiting. For example, the use of the term "automatic" may involve fully automatic or semi-automatic implementations involving user or administrator control over certain aspects of the implementation, depending on the desired implementation of one of ordinary skill in the art practicing implementations of the present application. The terms enhanced node B (eNodeB), small cell (SC), base station (BS) and pico cell may be utilized interchangeably throughout the example implementations. The implementations described herein are also not intended to be limiting, and can be implemented in various ways, depending on the desired implementation.

[025] In the related art, base stations improve spatial reuse by using directional antennas in the horizontal plane to create multiple horizontal sectors from the same NodeB. However this may be insufficient for future data demand in upcoming cellular networks. For example, the majority of data in the future may be generated indoors in urban settings. The landscape of a typical urban area is filled with buildings with varying heights from a large number of low rise residential and office buildings to a relatively low number of medium to high rise buildings. In such a situation, a new paradigm of network operations may be needed to optimize performance.

[026] Example implementations described herein are directed to forming additional sectors in the vertical domain (called vertical sectorization) for a base station (BS). Example implementations may involve various methods of forming and operating vertical sectors. Example implementations may involve a BS configured with a two dimensional active antenna grid such as in a Full Dimensional Multiple Input Multiple Output (FD- MIMO) system. In example implementations, a network operator can create vertical sectors, perform initial configuration and optimize the subsequent data rate performance by using the proposed long term evolution (LTE) transmission mode.

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DOCS 120179-HIT020/1945344.1 [027] A sector (vertical or horizontal) is defined by the direction of its main lobe; its half power beamwidth (HPBW) and its maximum transmit power. Example implementations may involve various aspects. In one aspect, the distribution of the vertical angles of the users is computed and used to form vertical sectors. In another aspect, the parameters of the vertical sectors may be configured based on first computing the distribution of the elevation angles of the users. Such parameters can include the HPBW (which influences the width) of the vertical sectors, the total available transmit power at the base site among vertical sectors, the optimal number of vertical sectors, and the tilt (which influences the direction of the main lobe) of the vertical sectors.

[028] In example implementations, once a vertical sector has been formed, a new long term evolution advanced (LTE-A) transmission mode (TM) may be utilized to serve the UEs of the higher sectors more effectively.

[029] In the related art, the parameters of the horizontal sectors are chosen such that the azimuth plane is divided uniformly. However, in example implementations, the vertical sectors do not need to be chosen uniformly. Example implementations involve methods for designing the vertical sectors, in terms of the number of vertical sectors needed, and their corresponding parameters (vertical tilt and HPBW).

[030] The design of vertical sectors in example implementations is based on the inherent non-uniformity in the UE distribution profile in the zenith domain. In urban and suburban environments, UEs are located in buildings (offices, residential buildings, etc.) and the height distribution of UEs is dependent on the height distribution of buildings. The distribution of building heights can be relatively uniform across an urban area in cities like Paris where most buildings have 3 to 5 floors. It can also be highly non-uniform with a large number of lower height buildings (3-5 floors) and a small number of higher rise buildings (30-50 floors). The buildings' height distribution naturally leads to a long term non-uniform UE distribution in the vertical domain.

[031] FIG. 4(a) illustrates an example base station upon which example implementations can be implemented. The block diagram of a base station 400 in the example implementations is shown in FIG. 4(a), which could be a macro base station or an enhanced Node B. The base station 400 may include the following modules: the Central

Processing Unit (CPU) 401, the baseband processor 402, the transmission/receiving

(Tx/Rx) array 403, the Xn interface 404, and the memory 405. The CPU 401 is configured to execute one or more modules as described in this disclosure. The baseband processor 402 generates baseband signaling including the reference signal and the system

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DOCS 120179-HIT020/1945344.1 information such as the cell-ID information. The Tx/Rx array 403 contains an array of antennas which are configured to transmit according to various vertical sectors based on the example implementations described herein. The antennas may be grouped arbitrarily to form one or more active antenna ports. The Xn interface 404 is used to exchange traffic and interference information between two base stations via a backhaul to transmit instructions to other base stations as needed. The memory 405 is configured to store information regarding the parameters for the Tx/Rx array, and is further configured to store modules for execution by the CPU 401. The modules can include the data processing module 405- 1 , the sector optimization module 405-2, and the cost function optimization module 405-3. Memory 405 may take the form of a computer readable storage medium or can be replaced with a computer readable signal medium as described below.

[032] In example implementations, the UE density is tracked in the vertical domain and used to design the parameters of the vertical sectors. FIG. 4(b) illustrates example modules at the base station for configuring the vertical sectors in accordance with example implementations. The data processing module 405- 1 and sector optimization module 405- 2 can be stored in memory 405 and executed by CPU 401.

[033] The data processing module 405- 1 performs several functions. At 410 the data processing module 405- 1 collects information about the UE elevation angles. The information can be a combination of long term statistics of UE position information/channel state feedback from LTE reference signals such as PRS (positioning reference signals) and CSI-RS (channel state information reference signals) and terrain and building height information obtained from the city planning authorities. An example flow diagram for the information collection is illustrated in FIG. 5.

[034] At 420, based on the elevation angle information obtained at 410, the data processing module 405- 1 constructs a probability distribution of users from the elevation angle. An example implementation of the probability distribution is described in relation with FIG. 6.

[035] The sector optimization module 405-2 performs the following functions. At 430, the sector optimization module 405-2 defines a cost function in terms of the distribution / (Θ) of the vertical tilt Θ determined from the data processing module 405- 1 , the HPBW 0_3dB , the power P per sector, and the total number of sectors N .

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DOCS 120179-HIT020/1945344.1 [036] At 440, for a given value of N , the sector optimization module 405-2 can calculate ( Θ_3(1Β , Ρ ) based on the location of the sector, and the number of UEs within the sector. Examples 2 and 3 illustrate examples for determining Θ_ΜΒ and P .

[037] FIG. 5 illustrates an example flow diagram for the information collection, in accordance with an example implementation. The flow in FIG. 5 corresponds to the function of the data processing module 405- 1 to collect UE elevation angle information as illustrated by the flow at 410. The data processing module 405- 1 can collect UE elevation angle information 501 from various sources. From a first source, the data processing module 405- 1 can estimate the elevation angle of each associated UE from LTE PRS, CSI- RS, Sounding Reference Signal (SRS) and other methods as shown at 502. From a second source, the data processing module 405- 1 may obtain the statistics of buildings in the city (e.g. height, density, etc.) and the user population profile of the city from the planning office as shown at 503.

[038] In an example implementation, the UE position (height) can be derived using LTE- A positioning techniques. LTE specifies multiple methods to obtain UE positioning. One of them is PRS based Observed Time Difference Of Arrival (OTDOA) and another is enhanced cell-ID related positioning. In the related art, these techniques were mostly used for obtaining the UE position in the horizontal (azimuth) plane. In example implementations, UE positioning techniques may be used to obtain the UE coordinates, including its height (position in the vertical dimension). Positioning reference signals (PRS) can be used to estimate the position of the UE including its height. For the case of enhanced cell- ID positioning, the eNB can estimate, in addition to the AoA (azimuth angle of arrival) present in the LTE standard, the ZoA (zenith angle of arrival). The AoA and ZoA are estimated from the uplink transmission of the UE (SRS or DMRS), taking into account both the horizontal and the vertical antenna spacing of the antenna array at the eNB.

[039] In another example implementation, the base station may be directed to serve a specific set of buildings, wherein the base station can infer the height of the UE based on the distribution of heights of these set of buildings. The elevation angle is derived from the information received from the UE and the elevation angle information for each UE is stored for future reference by the base station. An example implementation of the storage of the elevation angle information is illustrated in Table I.

[040]

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DOCS 120179-HIT020/1945344.1 UE ID Elevation Angle

1 27

2 54

3 65

Table I - Elevation Angle of each UE served by the base station.

[041] In addition to the elevation angle, the UE probability distribution over height or elevation angle can be calculated from long term statistics of all UEs served by the base station. The statistics can be based on the reference signals received from the UE to determine the probability distribution of the UE height. The probability distribution can be split by sector, or by time, or by other methods according to the desired implementation. The probability distribution can be initially determined based on information provided by the city planner or building planner, and then subsequently updated over time by the base station.

[042] FIG. 6 illustrates a relationship of the elevation angle with two dimensional distance and user height, in accordance with an example implementation.

[043] Example 1 : Consider that the distribution of building heights in a city follows an exponential distribution, which may be a reasonable model for many urban environments. Assuming, on average, an equal number of users in each floor per building, it can be shown that the random variable h denoting the height distribution of users is also exponentially distributed. Let the distribution of h be (h) = where a is the parameter of the exponential distribution. A higher value of a implies a faster decay of the distribution, i.e. the city has a large number of low-rise buildings with a few high-rises. The value of a is determined from city planners or from city profile information as illustrated in FIG. 5. Let r be a random variable denoting the two dimensional distance between the user and the base station. The various parameters are shown in FIG. 6, where h_BS is the height of the base station.

[044] It can be seen from FIG. 6 that tan(#) =— -— .

h - h_BS

[045] Note that Θ = 0 is the minimum value of Θ corresponding to the users at the

Tc h topmost floor (theoretically taken to be at a height of infinity) and Θ =— h tan^-1—— is its

2 r

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DOCS 120179-HIT020/1945344.1 maximum value which corresponds to the user at the ground level. The distributions of h (exponential) and r (uniform) are known. Accordingly it can be shown that the conditional distribution of the elevation angle given the two dimensional distance is of the form, f(6 I r) = are ^{a BS} . The marginal distribution of Θ , f{6) , is found by sin (Θ)

averaging over r .

[046] FIG. 7 illustrates a probability distribution function of the elevation angles of users for different parameters of building density. Example functions are shown in FIG. 7 for different values of r , h and a . It shows that for a city where the building height increase is sharp (i.e. relatively high a ) the elevation angle distribution peaks at the maximum possible value, i.e. when at the ground level (as qualitatively there is relatively more low- rise buildings than high-rises) while for other city scenarios, the distribution peak may be at different angles Θ .

[047] Example 2: A criterion for choosing the HPBW θ_3άΒ of the vertical sectors to be created.

[048] Vertical sectors that are oriented 'upwards' (i.e. smaller value of tilt as illustrated in FIG. 1) can have wider HPBWs than those that are oriented 'downwards'. This can be the case if the sector is to serve a relatively small number of users with a large zenith angular spread to cover all the users located at or above a certain floor level. For example, if there is only one high rise building in a horizontal sector, surrounded by lower height buildings. The upward sector can be used to serve all the users located above a certain floor in the high rise building, thus covering a large number of floors, and a wide angular spread.

[049] For a sector designed to serve users at or directly above ground level, multiple beams with smaller HPBW Θ_ΜΒ can be used, to serve more users simultaneously with improved quality of service.

[050] FIG. 8 illustrates different vertical sectors with increasing tilts, in accordance with an example implementation. In an example implementation, to ensure a relatively equal load of users distributed among the various sectors formed; the HPBW of two sectors can be formed as a function of the number of users in the sector. A larger HPBW can be used for a sector tilted upward to ensure that it covers a larger number of users, while a lower HPBW can be used to serve users in the lower or downward tilted sector, where a higher

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DOCS 120179-HIT020/1945344.1 concentration of users is located in a relatively smaller zenith angular spread. This is illustrated in FIG. 8 with three different vertical sectors.

[051 ] Example 3 : A criterion for choosing the transmit powers of the vertical sectors to be created.

[052] For a fixed value of HPBW θ_3άΒ , vertical sectors that are oriented 'upwards' (i.e. smaller value of tilt as illustrated in FIG. 1) can be allocated lower power than those that are oriented "downward" to serve a larger concentration of users, per the user density f(ff) of Example 1. This is depicted by the differing HPBW of FIG. 8.

[053] In another example, if the sectors are to divide the horizontal plane onto an inner and outer sector for example, the outer sector, with a lower tilt value, may need to be allocated more power to serve users located on the cell edge. Thus, depending on the UE distribution, the transmit power will be optimized in conjunction with HPBW to serve all the users with a certain quality of service.

[054] FIG. 9 illustrates a cost function optimization module, in accordance with an example implementation. After defining the cost function as a function of the HPBW, power and the density of the UE, example implementations may involve a method that uses the design criteria discussed in the previous two examples, and runs an optimization algorithm to determine the values of number of vertical sectors, their tilts, HPBWs and the transmit powers.

[055] In the flow diagram of FIG. 9, an iterative algorithm is presented for computing the parameters of the vertical sector. The iteration is over N, the number of vertical sectors. At

900, a cost function is defined as a function of HPBW, power and density of the UE. At

901, a value of N for the number of sectors is fixed (starting from one) and then the HPBW and the transmit powers are selected per given design guidelines as a function of the UE distribution at 902. Examples 2 and 3 are examples of such design guidelines as described above.

[056] The design guidelines are used to optimize a cost function to obtain the value of the tilts for all the sectors at 903. At 904, a check is performed to determine if the value of the cost function is further minimized. If so (YES) then the value of N is increased by one and all of the operations are repeated from the flow at 902. If not (NO), the flow diagram stops to choose the last value of N.

[057] Various example of cost functions are described below:

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DOCS 120179-HIT020/1945344.1 [058] a) Minimum Mean Square Error (MMSE) criterion:

[059] This cost function computes the MMSE error as the tilt deviates from the actual elevation angles

[060] b) Antenna Gain (dB)

[061] This cost function mimics the response of commonly used vertical antenna patterns, where the formula of the antenna gain pattern is in decibels.

j tilt

[062] c) Antenna Gain (linear): U _AntennaL (N) =∑ exp n /

[063] This cost function mimics the response of commonly used vertical antenna patterns.

[064] The following is an example of the cost function optimization procedure. At the first step Ν =1. Let Θ_ΜΒ = 70 degrees. This value is chosen as a single beam has to cover all UEs spread along the zenith direction. Note that 0_idB may be any value depending on the desired implementation and the desired constraints.

[065] The cost function optimization is thus

[066] For certain conditions on the various functions it can be shown that the optimal tilt is either 0 or 180 degrees or given by the solution of

[067] The solution for higher values of N can be performed in a similar way with some additional assumptions such as the separation between two vertical sectors.

[068] The above example implementations illustrated methods to construct vertical sectors and configure their parameters (HPBW, P). Example implementations also involve transmission modes for vertical sectors, such as those that are pointed upwards.

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DOCS 120179-HIT020/1945344.1 [069] In LTE a transmission mode defines a UE and network behavior. The LTE transmission mode may involve the transmission scheme (e.g. Single User/Multiple User MIMO (SU/MU-MIMO), Coordinated Multipoint (CoMP)), the configured periodicity and granularity (e.g., wideband, sub-band) of UE feedback, and the type of control information (e.g., downlink control information (DCI) formats) that the BS has to send to the UE along with data, so that the UE can decipher the data.

[070] In example implementations, the various components of a transmission mode (TM) may be set/optimized to transmit to UEs in vertical sectors with low tilts (pointing 'upwards') and may require a new transmission mode.

[071] FIG. 10 illustrates how the channel characteristics may vary depending on the vertical sector tilt, in accordance with an example implementation. As illustrated in FIG. 10, the characteristics of the wireless channels may vary significantly depending on the tilt of the vertical sector. The sectors with a lesser value of tilt (pointed 'upwards') will serve UEs that experience less building clutter and hence may have a higher line of sight probability than sectors with higher tilt, that may offer a richer scattering channel. The increase of line of sight (LoS) probability with UE height is shown in FIG. 1 1, which illustrates a variation of LoS probability with UE height for a 3D urban macro (UMa) channel. The 2D distance between the BS and the UE is 100 meters in the example of FIG. 1 1.

[072] The increased probability of LoS links in 'upward' vertical sectors implies that transmission schemes such as MU-MIMO vertical beamforming can lead to higher throughput. To facilitate example implementations, feedback and DCI formats can be utilized that are optimized for MU-MIMO beamforming for transmissions to UEs in these sectors. Related art implementations of LTE do not have a dedicated transmission mode for MU-MIMO. Rather transmission mode 9 (TM9) which supports MU-MIMO has been designed to implement either SU-MIMO or MU-MIMO in a manner transparent to the UE. Thus features that may have benefitted transmission to multiple users, such as MU channel quality indicator (CQI), may not have been included in TM9 to maintain the UE transparency property. Accordingly, example implementations may therefore utilize an MU-CQI.

[073] In addition, example implementations may also involve different codebooks for efficient feedback when the channels have variations in both azimuth and elevation (as is the case in vertical sectors). Example implementations can therefore utilize a new TM for efficient feedback mechanisms using the different codebooks.

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DOCS 120179-HIT020/1945344.1 [074] Further, MU-MIMO is provided as an example transmission, however, other LTE transmission modes may be utilized for serving UEs in vertical sectors.

[075] The implementation of multiple transmission modes by the base station can also vary over time based on the UE height probability distribution. For example, the base station may determine that the vertical sectors may change during the evening, or during a lunch hour when the UE distribution may cluster to a portion of a building (e.g. a cafeteria). Thus, multiple transmission modes can be used by the base station, which may change depending on time. The base station may also re-compute the sectors for each scheme, depending on the desired implementation, and store the transmission modes in memory for future reference by the base station. An example implementation of the storage of the transmission modes is illustrated in Table II.

Table II - Transmission modes with time period of each transmission mode, sectors and tilt parameters

[076] By implementation of transmission modes as illustrated in Table II, the transmission mode can thereby change depending on the time of day. Further, the table may include values for parameters such as HPBW and power per sector to adjust the width and the power of the transmit beam of the base station for each vertical sector.

[077] Finally, some portions of the detailed description are presented in terms of algorithms and symbolic representations of operations within a computer. These algorithmic descriptions and symbolic representations are the means used by those skilled in the data processing arts to most effectively convey the essence of their innovations to others skilled in the art. An algorithm is a series of defined steps leading to a desired end

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DOCS 120179-HIT020/1945344.1 state or result. In example implementations, the steps carried out require physical manipulations of tangible quantities for achieving a tangible result.

[078] Unless specifically stated otherwise, as apparent from the discussion, it is appreciated that throughout the description, discussions utilizing terms such as "processing," "computing," "calculating," "determining," "displaying," or the like, can include the actions and processes of a computer system or other information processing device that manipulates and transforms data represented as physical (electronic) quantities within the computer system's registers and memories into other data similarly represented as physical quantities within the computer system's memories or registers or other information storage, transmission or display devices.

[079] Example implementations may also relate to an apparatus for performing the operations herein. This apparatus may be specially constructed for the required purposes, or it may include one or more general-purpose computers selectively activated or reconfigured by one or more computer programs. Such computer programs may be stored in a computer readable medium, such as a computer-readable storage medium or a computer-readable signal medium. A computer-readable storage medium may involve tangible mediums such as, but not limited to optical disks, magnetic disks, read-only memories, random access memories, solid state devices and drives, or any other types of tangible or non-transitory media suitable for storing electronic information. A computer readable signal medium may include mediums such as carrier waves. The algorithms and displays presented herein are not inherently related to any particular computer or other apparatus. Computer programs can involve pure software implementations that involve instructions that perform the operations of the desired implementation.

[080] Various general-purpose systems may be used with programs and modules in accordance with the examples herein, or it may prove convenient to construct a more specialized apparatus to perform desired method steps. In addition, the example implementations are not described with reference to any particular programming language. It will be appreciated that a variety of programming languages may be used to implement the teachings of the example implementations as described herein. The instructions of the programming language(s) may be executed by one or more processing devices, e.g., central processing units (CPUs), processors, or controllers.

[081] As is known in the art, the operations described above can be performed by hardware, software, or some combination of software and hardware. Various aspects of the example implementations may be implemented using circuits and logic devices

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DOCS 120179-HIT020/1945344.1 (hardware), while other aspects may be implemented using instructions stored on a machine-readable medium (software), which if executed by a processor, would cause the processor to perform a method to carry out implementations of the present application. Further, some example implementations of the present application may be performed solely in hardware, whereas other example implementations may be performed solely in software. Moreover, the various functions described can be performed in a single unit, or can be spread across a number of components in any number of ways. When performed by software, the methods may be executed by a processor, such as a general purpose computer, based on instructions stored on a computer-readable medium. If desired, the instructions can be stored on the medium in a compressed and/or encrypted format.

[082] Moreover, other implementations of the present application will be apparent to those skilled in the art from consideration of the specification and practice of the teachings of the present application. Various aspects and/or components of the described example implementations may be used singly or in any combination. It is intended that the specification and example implementations be considered as examples only, with the true scope and spirit of the present application being indicated by the following claims.

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DOCS 120179-HIT020/1945344.1

Claims

CLAIMS What is claimed is:

1. A base station, comprising:

a transmission array configured to create one or more vertical sectors to transmit at one or more user equipment (UE) served by the base station based on one or more parameters of the one or more vertical sectors;

a memory configured to store a distribution of elevation angles of the one or more user equipment (UE) served by the base station; and

a processor configured to calculate the one or more parameters of the one or more vertical sectors based on the distribution of elevation angles of the one or more UE served by the base station.

2. The base station of claim 1, wherein the processor is configured to compute the distribution of elevation angles based on an estimation of elevation angles of the one or more UE served by the base station from one or more reference signals of the one or more UE served by the base station.

3. The base station of claim 1, wherein the processor is configured to compute the distribution of elevation angles based on a UE height probability distribution.

4. The base station of claim 1, wherein the one or more parameters comprises a half power beam width (HPBW), wherein the processor is configured to calculate the HPBW based on a cost function.

5. The base station of claim 1, wherein the one or more parameters comprises a vertical tilt, wherein the processor is configured to calculate the vertical tilt based on a cost function.

6. The base station of claim 1, wherein the memory is configured to create a new

LTE transmission mode defining a mode of transmission for each of the one or more vertical sectors and manage this newly created LTE transmission mode with pre-existing

LTE transmission modes, wherein the transmission array is configured to transmit according to the one or more transmission modes.

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DOCS 120179-HIT020/1945344.1

7. A method, comprising:

managing a distribution of elevation angles of one or more user equipment (UE) served by a base station;

calculating one or more parameters of one or more vertical sectors based on the distribution of elevation angles of the one or more UE served by the base station; and

Creating the one or more vertical sectors for transmission to one or more user equipment (UE) served by the base station based on the one or more parameters of the one or more vertical sectors.

8. The method of claim 7, further comprising computing the distribution of elevation angles based on an estimation of elevation angles of the one or more UE served by the base station from one or more reference signals of the one or more UE served by the base station.

9. The method of claim 7, further comprising computing the distribution of elevation angles based on a UE height probability distribution.

10. The method of claim 7, wherein the one or more parameters comprises a half power beam width (HPBW), wherein the calculating the one or more parameters comprises calculating the HPBW based on a cost function.

1 1. The method of claim 7, wherein the one or more parameters comprises a vertical tilt, wherein calculating the one or more parameters comprises calculating the vertical tilt based on a cost function.

12. The method of claim 7, further comprising creating a new LTE transmission mode defining a mode of transmission for each of the one or more vertical sectors and managing this newly created LTE transmission mode with pre-existing LTE transmission modes, wherein each of the one or more transmission modes defining a mode of transmission for each of the one or more vertical sectors; and transmitting according to the one or more transmission modes.

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DOCS 120179-HIT020/1945344.1

13. A non-transitory computer readable medium storing instructions for executing a process, the instructions comprising:

calculating one or more parameters of the one or more vertical sectors based on the distribution of elevation angles of the one or more UE served by the base station; and

Creating the one or more vertical sectors to transmit to one or more user equipment (UE) served by the base station based on the one or more parameters of the one or more vertical sectors.

14. The non-transitory computer readable medium of claim 13, wherein the instructions further comprise computing the distribution of elevation angles based on an estimation of elevation angles of the one or more UE served by the base station from one or more reference signals of the one or more UE served by the base station.

15. The non-transitory computer readable medium of claim 13, wherein the instructions further comprise computing the distribution of elevation angles based on a UE height probability distribution.

16. The non-transitory computer readable medium of claim 13, wherein the one or more parameters comprises a half power beam width (HPBW), and wherein the calculating the one or more parameters comprises calculating the HPBW based on a cost function.

17. The non-transitory computer readable medium of claim 13, wherein the one or more parameters comprises a vertical tilt, and wherein the calculating the one or more parameters comprises calculating the vertical tilt based on a cost function.

18. The non-transitory computer readable medium of claim 13, wherein the instructions further comprise creating a new LTE transmission mode and managing this newly created transmission mode with pre-existing LTE transmission modes, each of the one or more transmission modes defining a mode of transmission for each of the one or more vertical sectors; and transmitting according to the one or more transmission modes.

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DOCS 120179-HIT020/1945344.1