WO2011071470A1 - Système et procédé d'amélioration des performances de stations de base à l'aide d'un réseau d'antennes coordonnées - Google Patents

Système et procédé d'amélioration des performances de stations de base à l'aide d'un réseau d'antennes coordonnées Download PDF

Info

Publication number
WO2011071470A1
WO2011071470A1 PCT/US2009/006458 US2009006458W WO2011071470A1 WO 2011071470 A1 WO2011071470 A1 WO 2011071470A1 US 2009006458 W US2009006458 W US 2009006458W WO 2011071470 A1 WO2011071470 A1 WO 2011071470A1
Authority
WO
WIPO (PCT)
Prior art keywords
base stations
patterns
base station
codebook
btss
Prior art date
Application number
PCT/US2009/006458
Other languages
English (en)
Inventor
Yan Hui
Original Assignee
Airhop Communication, Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Airhop Communication, Inc. filed Critical Airhop Communication, Inc.
Priority to CN200980162265.9A priority Critical patent/CN102612832B/zh
Priority to PCT/US2009/006458 priority patent/WO2011071470A1/fr
Publication of WO2011071470A1 publication Critical patent/WO2011071470A1/fr

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00—Baseband systems
    • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
    • H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
    • H04L25/03006—Arrangements for removing intersymbol interference
    • H04L25/03343—Arrangements at the transmitter end
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/022—Site diversity; Macro-diversity
    • H04B7/024—Co-operative use of antennas of several sites, e.g. in co-ordinated multipoint or co-operative multiple-input multiple-output [MIMO] systems
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/0408—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas using two or more beams, i.e. beam diversity
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L5/00—Arrangements affording multiple use of the transmission path
    • H04L5/003—Arrangements for allocating sub-channels of the transmission path
    • H04L5/0058—Allocation criteria
    • H04L5/0073—Allocation arrangements that take into account other cell interferences
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/06—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
    • H04B7/0613—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission
    • H04B7/0615—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal
    • H04B7/0619—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal using feedback from receiving side
    • H04B7/0636—Feedback format
    • H04B7/0639—Using selective indices, e.g. of a codebook, e.g. pre-distortion matrix index [PMI] or for beam selection
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L5/00—Arrangements affording multiple use of the transmission path
    • H04L5/0001—Arrangements for dividing the transmission path
    • H04L5/0003—Two-dimensional division
    • H04L5/0005—Time-frequency
    • H04L5/0007—Time-frequency the frequencies being orthogonal, e.g. OFDM(A), DMT
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W16/00—Network planning, e.g. coverage or traffic planning tools; Network deployment, e.g. resource partitioning or cells structures
    • H04W16/24—Cell structures
    • H04W16/28—Cell structures using beam steering
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W52/00—Power management, e.g. TPC [Transmission Power Control], power saving or power classes
    • H04W52/04—TPC
    • H04W52/38—TPC being performed in particular situations
    • H04W52/42—TPC being performed in particular situations in systems with time, space, frequency or polarisation diversity

Definitions

  • This invention pertains to wireless communications and to applying smart antenna techniques in a coordinated way among a group of base stations, such as Femtocells, to reduce interference or manage how interference happens.
  • Antenna arrays provide an efficient way to transmit and receive signals to improve the capacity, data throughput and link range by overcoming undesired channel conditions.
  • the beam pattern for an antenna array can be created by a weight vector which essentially modifies either or both of amplitude and phase of the signal transmitted or received by the antenna. While applying weights can be done by hardware in the radio frequency (RF) domain, it is usually more efficient and practical to apply them in the digital domain.
  • RF radio frequency
  • Beam forming is a signal processing technique used in sensor arrays for directional signal transmission or reception.
  • a beam former controls the phase and relative amplitude of the signal at each transmitter, in order to create a desired signal pattern.
  • information from different sensors is combined in such a way that the expected pattern of the radiation is recovered.
  • the adjustment is usually done either in the analog domain or in the digital domain via the so-called antenna weight.
  • weight can be represented by an array of complex numbers.
  • the spatial selectivity is achieved by using adaptive or fixed receive/transmit beam patterns.
  • it is the adaptive beam forming that has promised much bigger performance improvements in wireless systems.
  • Adaptive beam forming systems usually require certain feedback of the channel information from the device at the other end of the communication system or estimates of the information in order to determine how to adjust the antenna weights.
  • MIMO is the use of multiple antennas at both the transmitter and receiver to improve communication performance.
  • a transmitter sends multiple streams by multiple transmit antennas.
  • the transmit streams go through a matrix channel which consists of multiple paths between multiple transmit antennas at the transmitter and multiple receive antennas at the receiver.
  • the receiver gets the received signal vectors by the multiple receive antennas and decodes the received signal vectors into the original information.
  • SISO single-in-single-out
  • SIMO single-in-multiple-out
  • MISO multiple-in- single-out
  • open-loop MIMO and closed-loop MIMO.
  • transmit diversity for example, Space-Time Transmit Diversity (STTD) used in Universal Mobile Telecommunications Systems (UMTS) standard and cdma2000 standard.
  • STTD Space-Time Transmit Diversity
  • UMTS Universal Mobile Telecommunications Systems
  • cdma2000 Code Division Multiple Access
  • An example of open-loop SIMO is receiver diversity with MRC combining or switched receiver diversity.
  • MIMO sometimes can be divided into three main categories, spatial multiplexing, transmit diversity or space-time coding, and pre- coding.
  • Pre-coding can be viewed as a generalized beam forming that can support single- layer or multi-layer transmission in MIMO systems. In the absence of scattering, beam forming results in a well-defined directional pattern, but in general, cellular conventional beams are not a good analogy. When the receiver has multiple antennas, the transmit beam forming cannot simultaneously maximize the signal level at all of the receive antennas and pre-coding is used.
  • a pre-coding scheme can be used in a MIMO system where the antenna configuration is pre-defined.
  • a codebook that defines the weights can be derived based on the desired directional beam patterns. This type of pre-coding is very much overlapped with the adaptive beam forming based on estimation. In the detailed description, we do not distinguish this from adaptive beam forming based on estimation.
  • Pre-coding can also be used in a MIMO system where the antenna configuration is not pre-determined. In that case, the codebook is derived based on criteria such as maximizing the signal level under certain channel conditions. Note that pre-coding requires knowledge of the channel state information (CSI) at the transmitter.
  • Pre-coding has been used in 4G wireless standards such as Long Term Evolution (LTE).
  • Placement of the antenna in an antenna arrays is very important.
  • the antenna spacing in a uniform linear array should be around ⁇ 12 while for MIMO, the preferable antenna interval is around 4 ⁇ to l0/l .
  • a uniform circular array is another way to place the antenna.
  • Certain embodiments as disclosed herein provide for applying smart antenna technique in a coordinate way among a group of BTSs, such as Femtocells, to avoid, reduce interference or manage how interference happens to achieve performance enhancement such as higher system throughput or better QoS to individual applications.
  • a method of wireless base station performance enhancement using coordinated beam forming in a system of base stations having a plurality of wireless base stations having antenna systems capable of beam forming includes identifying neighboring base stations and determining characteristics of the neighboring base stations to be used to determine desired beam forming for two or more of the base station.
  • the antenna system of two or more of the base stations are then configured based upon the determined characteristics to create a null beam directed toward a neighboring base station to reduce interference with that neighboring base station.
  • configuring the antenna system of one or more of the base stations to create a null beam further comprises creating a receive null beam.
  • Another aspect of the method includes measuring signals received from the neighboring base stations to determine the direction and distance of one or more of the neighboring base stations. Additionally the method can include coordinating transmission characteristics of two or more of the base stations.
  • transmission characteristics are selected from the group comprising transmit power, time, frequency resources, time-frequency resources.
  • the method can include determining the characteristics of the system by a central authority. Alternatively, the determining characteristics of the system is coordinated amongst the base stations.
  • a method of wireless base station performance enhancement using coordinated beam forming in a wireless network having a plurality of wireless base stations having antenna systems capable of beam forming includes identifying neighboring base stations and configuring the antenna system of two or more of the base stations to create a beam pattern to reduce interference with that neighboring base station.
  • the beam pattern can include using frequency division in areas of common coverage for the two or more base stations. Further, the beam pattern can include using time-frequency division in areas of common coverage for the two or more base stations.
  • the antenna configurations are selected from a subset of configurations in a codebook of patterns to select patterns having stronger beam pattern in the direction of subscribers and weaker beam patterns in the direction of neighboring base stations.
  • a further aspect includes a base station for performance enhancement using coordinated beam forming in a system of base stations.
  • the base station includes an air- interface transceiver system which provides wireless communications with associated subscribers and which performs beam forming and includes an antenna system capable of beam forming; a second receiver configured to perform measurements of signals transmitted by other base stations; and a control unit in communication with the subscriber air-interface system and the second receiver for sending instructions to the subscriber air-interface system for configuring the antenna system of the subscriber air-interface system based upon characteristics of one or more neighboring base stations to create a null beam directed toward a neighboring base station to reduce interference with that neighboring base station.
  • Figure 1 shows a typical Femtocell system where the Femtocell BTSs are connected to the core networks through broadband connections. The provisioning of individual Femtocell BTS is done by the core network on per device basis.
  • FIG. 2a shows one embodiment of a Femtocell system where the Femtocell BTSs are connected to core networks through wired or wireless broadband connections.
  • the Femtocells are networked via either a wired backhaul or over-the-air.
  • the provisioning of the Femtocell BTSs can be done either by the core network on a per device basis or in a coordinated fashion either under the complete supervision of the core networks, partial supervision of the core networks or without supervision at all.
  • FIG. 2b of a block diagram of a Femtocell BTS.
  • Figure 3 plots beam pattern for a 4 elements Uniform Linear Array with the distance between the elements being half a wavelength.
  • Figure 4 shows an example of the creation of a null beam by a Femtocell BTS in the direction of a neighboring BTS.
  • Figure 5 shows an example where creation of null beams by two Femtocell BTSs in the direction of neighboring BTSs would cause problem for one of the BTSs. It also shows the solution where the BTSs periodically scan the null beam pattern direction to detect whether any subscribers exists.
  • Figure 6 illustrates transmit power adjustment on the beam so that the BTSs can service their subscribers s while controlling the interference with the neighboring subscribers.
  • Figure 7 shows an example of time-division multiplex of beams between neighbor BTSs.
  • Figure 8 shows an example of frequency-division multiplexing (based on subchannel groups) of beams between neighbor BTSs.
  • Figure 9 shows an example of time-frequency division multiplexing (based on time- frequency resource groups) of beams between neighbor BTSs.
  • Figures 10a to lOd show an example of coordinated beam forming based on spatial/directional, time, frequency, and time-frequency multiplexing by a group of BTSs.
  • Figure 11 illustrates an example of BTSs using directional beam forming and coordinative measurement from the neighbor BTSs to determine the direction and distance of the neighbor BTSs.
  • Figure 12 illustrates beam patterns using a codebook defined in the 3GPP LTE standard for down link and applied to a 4 elements ULA with the distance between the elements being a half wavelength.
  • Figure 13 illustrates beam patterns using the codebook defined in 3GPP LTE standard for down link and applied to a 4 elements UCA with the distance between the elements being 0.42 wavelength.
  • Figure 14 illustrates an example of coordinated beam forming based on spatial and directional codebook partitioning by a group of BTSs.
  • Figure 15 illustrates an example of coordinated beam forming based on time, frequency, and time-frequency multiplexing by a group of BTSs.
  • a group of base stations can be managed by a centralized network management identity or can be self-organized by communicating with each other via wireless air-interfaces or wired interfaces.
  • the term base station also refers to access points.
  • One such example are Femtocell systems.
  • FIG. 1 shows a Femtocell system where Femtocell BTSs 10 are managed by a core network. Femtocells are connected to core networks 12 over the internet 14 and radio network controller (RNC) 16 through broad band connections. The provisioning of individual Femtocell BTSs is done by the core network via provisioning server 15 on a per device basis.
  • RNC radio network controller
  • FIG. 2a shows a Femtocell system where Femtocell BTSs 200 are connected to the core networks 12 through wired or wireless broadband connections.
  • the Femtocells are networked via either a wired backhaul or over-the-air.
  • the provisioning of the Femtocell BTSs can be done either by the core network 12 on a per device basis or in a coordinated fashion either under the complete supervision of the core networks, partial supervision of the core networks or without supervision at all.
  • a Femtocell is a smaller cellular base station or access point of cellular network 18 that operates in either licensed frequencies, or if so desired, in unlicensed frequencies. It is typically designed for use in residential or small business environments.
  • Femtocells use the available broadband access, such as DSL, cable, or fixed wireless broadband access networks, to tunnel the user and control data through the broadband and connect to the cellular core network backhauls.
  • This is illustrated in Figure 1.
  • the femtocell incorporates the functionality of a typical base station but extends it to allow a simpler, self contained deployment; for example, a UMTS femtocell containing a Node B, and RNC with Ethernet for backhaul. Although much attention is focused on UMTS, the concept is applicable to all standards, including GSM, CDMA2000, TD-SCDMA and WiMAX solutions.
  • Adaptive beam forming can be performed based on certain measurements in order to determine the direction and strength of the beam patterns.
  • One example is Direction-Of- Arrival (DOA) based beam forming.
  • DOA Direction-Of- Arrival
  • the dominant direction of arrival is estimated using an antenna array with a certain geometry, e.g., Uniform Linear Array (ULA) or Uniform Circular Array (UCA), with a small inter-element distance (d ⁇ /2). This directional information is then utilized to steer a transmission beam created by linear weighting towards the terminal.
  • UOA Uniform Linear Array
  • UCA Uniform Circular Array
  • the Femtocell BTSs are connected to the core networks through broadband connection.
  • the provisioning of individual Femtocell BTS is done by the core network on a per device basis.
  • management and provisioning of Femtocell BTSs can be done either by the core network on a per device basis or in a coordinated fashion either under the complete supervision of the core networks (completely centralized), partial supervision of the core networks (partially centralized) or without supervision at all (distributed).
  • the BTS includes a Femtocell BTS device 200 that has a BTS air-interface transceiver system 210 for communications with associated subscribers.
  • the system 210 is a Femtocell system.
  • the BTS air-interface transceiver system includes an antenna system (examples of which are described herein) capable of performing beam forming.
  • the transceiver 210 performs the functions to provide wireless communication to and from subscribers.
  • Subscribers refers to devices that are receiving and/or transmitting signals to a BTS. Subscribers are typically associated with a BTS. Such devices are also referred to as user equipment (UE). Such devices are capable of transmitting and receiving wireless signals and include devices such as cellular telephones, and other electronic equipment, such as personal computers, which are equipped with a wireless transceiver.
  • UE user equipment
  • Such devices are capable of transmitting and receiving wireless signals and include devices such as cellular telephones, and other electronic equipment, such as personal computers, which are equipped with a wireless transceiver.
  • a second receiver 212 is included that can make measurements of other BTS transmitted signals. Alternatively, the BTS air-interface transceiver can be modified to make those measurements.
  • a control unit 214 is included that can communicate with a centralized server and/or with other Femtocell BTSs in a peer-to-peer fashion using central/peer communication unit 216 (for example, a Femto-server and Femto-Femto communication unit).
  • the control unit generates the instructions to the BTS transceiver 210 to implement the beam forming and coordination between BTSs as described herein.
  • Such a system uses a protocol and associated messages that support the communications between the Femtocell BTSs and centralized servers as well as communications between the control unit and the BTS transceiver 210.
  • the control unit includes a message parser for parsing received messages and a database for storing the neighbor list described below.
  • BTSs such as Femtocell base stations 200 that can network and coordinate with each other, as described above, coordinate how the beam forming is performed at each individual BTS in terms of beam direction, beam pattern, transmit power, time, frequency resources, time-frequency resources, respectively or collectively.
  • the objective of this coordination is to improve the network work performance and reduce interference, so the criteria used in the beam forming coordination includes, but is not limited to, pilot or reference signal strength, bit error rate or packet error rate, data throughput, required data rate, QoS requirements, and so on. This can be done either via a centralized fashion or via a distributed fashion. This can be done with the consideration of different antenna array configurations.
  • the output beam pattern after applying the weights w n is [047]
  • the complex weight vector w [w, ,vv 2 , -- vv A ,] r can be chosen in order to obtain a desired beam pattern for the transmitter.
  • the same equation can be applied to the receiver side and it results in receiver beaming forming.
  • receiver or transmitter beam patterns can be formed to enhance the desired transmitted or received signal or reduce the interfering signal(s) in certain directions or areas.
  • the neighboring Femtocell BTSs have the knowledge of the relative direction and relative distance of each other.
  • the terms “neighbor” and “neighboring” are used to refer to BTSs whose transmissions can impact the performance of each other. This knowledge can come from information sent to the central unit from the central/BTS communication unit 216 or from the 2nd receiver/measurement unit 212.
  • the UE air interface 210 of the Femtocell BTS applies appropriate weights to create one or more null beams on transmit or receive or both in the directions of the neighboring BTSs.
  • pointing a null pattern on the transmitter toward the neighboring BTSs can reduce the interference from the BTS to the UEs of the neighboring Femtocells on the downlink (DL) direction.
  • Applying a null pattern on the receiver toward the neighboring BTSs can reduce the interference from the UEs of the neighboring Femtocells to the said BTS on the uplink (DL) direction. This is illustrated in Figure 4 for two Femtocell base stations BTS1 and BTS2.
  • the BTS periodically "scans" the null beam area, e.g., apply weights so that it would transmit and receive signal in the original null beam directions periodically, in order to detect whether any UE is in or moved into the "null beam" area. The period can be determine either by network management parameters by the centralized server, by coordination of multiple BTSs or by individual BTS.
  • the BTS When a UE that needs services is detected, the BTS will apply the appropriate beam pattern to the original null beam in order to service the UE with proper performance requirements. This is illustrated in Figure 5, where BTS 1 initially created the null beam in the direction of BTS2 and detected UE1 when it scanned the null beam area. BTS1 then uses the proper beam pattern instead of null beam to communicate with UEl. Note that when there are UEs in the directional null beam pattern area from both BTSs, the above method still creates degradation of performance to the UEs.
  • the BTSs lower or increase their transmit power on the DL while monitoring the DL reception quality of the UEs using certain metrics, such as BER, PER, ACK/NACK from DL ARQ or Hybid-ARQ, and so on.
  • metrics such as BER, PER, ACK/NACK from DL ARQ or Hybid-ARQ, and so on.
  • BTSs would keep the transmit power level until one or more metrics are not satisfied. This is illustrated in Figure 6.
  • the BTSs uses the beam forming in a time-division multiplexing manner in a common coverage area where some of all the BTSs have UEs to be serviced. This is illustrated in Figure 7.
  • the BTSs essentially can manage the interference and thus improve the performance beyond just adjusting transmit power.
  • the time-division can be applied to both beam and null beam, on both DL and UL.
  • the BTSs can perform the operations in a completely centralized way controlled by the server at the gateway or core networks, partially distributed way, or completely distributed way via peer-to-peer communications.
  • each BTS uses the beam forming in a frequency-division manner.
  • the frequency- division can be applied to both the beam and null beam, on both DL and UL.
  • he BTSs can perform the operations in a completely centralized way controlled by the server at the gateway or core networks, partially distributed way, or completely distributed way via peer-to-peer communications.
  • each BTS uses the beam forming in a time-frequency division manner, as shown in Figure 9.
  • it means using different resources in the time-frequency plane so that the UEs belonging to different BTSs but in a common coverage area receive their data only in the specific time- frequency resources.
  • UE1 of BTS 1 and UE1 of BTS2 are in an area where both BTSs would interfere with each other, and this cannot be resolved by reducing the transmits power.
  • the BTSs can decide to use time-frequency resources in a way to satisfy certain performance requirements, for example, QoS requirements with certain data rate over certain period of time.
  • the BTSs can cooperatively allocate time-frequency resources for each UEs in that beam pattern coverage area, and apply the beam forming differently on each group of resources.
  • the time-frequency resource division can be applied to both beam and null beam, on both DL and UL.
  • he BTSs can perform the operations in a completely centralized way controlled by the server at the gateway or core networks, partially distributed way, or completely distributed way via peer-to-peer communications .
  • a group of BTSs can coordinate the beam forming in spatial/directional, transmit power, as well as time, frequency, time-frequency multiplexing, and allocate resources to the UEs in the beam pattern.
  • the BTSs can perform the operations in a completely centralized way, partially distributed way, or completely distributed way.
  • Different scheduling and coordination algorithms can be used following this principle and the detailed coordination methods will be described in a later section.
  • the BTSs use directional beam forming and coordinated measurement from the neighbor BTSs to determine the direction and distance of the neighbor BTSs.
  • BTS1 applies beam forming using certain reference signals in four thirty degree apart directions at given time intervals. The time and interval are known to neighbor BTSs.
  • the neighbor BTSs i.e. BTS2 and BTS3 in this example, are capable of measuring the DL reference signal and able to communicate peer-to-peer with the BTS1. They measure the signal strength at given time and report back to BTS1. Based on the time and measurements of the signal, BTS1 can determine the direction and relative distance of the neighbor BTSs.
  • the results depend on the measurement algorithm selected and the accuracy of the timing and beam forming algorithm selected. This information can be used to determine the direction of the neighbor BTSs that is important in some embodiments described above. It can also be used in other applications, for example, as input to the database and topology of the neighbor BTSs. Note that other algorithms, such as those used on DO A, can also be used.
  • the nth element of the array manifold is
  • the complex weight vector w [ ⁇ , , ⁇ 2 , ⁇ ⁇ ⁇ w ⁇ can be chosen in order to obtain a desired beam pattern the transmitter.
  • the same equation can be applied to the receiver side and it results in receiver beam forming.
  • the BTSs can coordinate the beam forming in spatial/directional, transmit power, as well as time, frequency, time-frequency multiplexing, as illustrated in Figures 10a to lOd.
  • the BTSs can perform the operations in a completely centralized way, partially distributed way, or completely distributed way. Different scheduling and coordination algorithms can be used following this principle and the detailed coordination methods will be described in a later section.
  • pre-coding with pre-defined codebook are used in some 4G standards, such as LTE.
  • a pre-coding scheme can be used in a MIMO system where the antenna configuration is pre-defined.
  • the codebook that defines the weights can be derived based on the desired directional beam pattern. It can also be used in a MIMO system where the antenna configuration is not pre-determined. In that case, the codebook is derived based on criteria such as maximizing the signal level under certain channel conditions.
  • the beam patterns for one transmission layer when using ULA with element spacing being XI 2 is shown in Figure 12 and that of using UCA with element spacing being 0.42A is shown in Figure 13.
  • the codebook can be partitioned into two or more subsets based on the direction or directional region of stronger beam patterns.
  • the Femtocell BTSs choose the subsets of the codebook that have stronger beam pattern in the direction of the UEs but avoid using the subsets that have stronger beam patterns in the direction of neighbor BTSs.
  • the LTE codebook for DL transmission with one layer is shown as an example for the above and following embodiments.
  • One possible way is to partition the 0 to 180 degree plane into 6 directional regions with 30 degree spacing, and group those with strong beam patterns in each directional region.
  • the weights subset include indices 3, 6, 7, 10, 12, 13, 14, 15, 16; for 30-60 degree, weights subset include indices 2, 6,
  • weights subset include indices 1, 5, 9, 10, 13, 16; for 90-120 degree, weights subset include indices 1, 4, 8, 9, 13, 16; for 120-150 degree, weights subset include indices.4, 7, 11, 14, 15; for 150-180 degree, weights subset include indices 3, 7, 10,
  • the same partitioning method can be applied to different directional regions.
  • the partitioning can be done in a similar way but it results in different subsets.
  • antenna array configuration such as an UCA shown in Figure 13
  • a similar partition method can be applied.
  • the codebook is partitioned into two or more subsets based on the direction of null beam patterns.
  • the Femtocell BTSs choose the subsets of the codebook that have null beams in the directions of neighbor BTSs.
  • indices include 1, 2, 4, 5, 8, 9, 11 ; for 30 degree null beam subset, indices include 1, 2, 4, 5, 7, 8, 9, 11, 12, 13, 16; for 60 degree null beam subset, indices include 1, 3, 4, 5, 6, 7, 8, 10, 12, 13,14, 15, 16; for 90 degree null beam subset, indices include 2, 3, 4, 5, 6, 7, 8, 9, 11.
  • the same partitioning method can be applied to different directions. When using omni directional antennas or directional antenna different than 90 degrees, the partition can be done in a similar way but it results in different subsets. For different antenna array configuration, such as an UCA shown in Figure 13, similar partitioning methods can be applied.
  • the codebook is partitioned into two or more subsets based on a combination of the direction of stronger beam patterns and null beam patterns.
  • the Femtocell BTSs choose the subsets of the codebook that have stronger beam pattern in the direction of the UEs but have null beam patterns in the direction of neighbor BTSs.
  • indices include 3, 6, 7; for beam covers 60-90 degree while having null beam in 30 degree direction, indices include 1, 5, 9, 13, 16.
  • the same partitioning method can be applied to different combinations of directional regions and directional nulls. When using omni directional antennas or directional antenna different than 90 degrees, the partition can be done in a similar way but it results in different subsets. For different antenna array configuration, such as an UCA shown in Figure 13, similar partitioning method can be applied.
  • the subsets of codebook can be applied to BTSs on DL or to UEs on UL in a time-division, frequency-division, or time- frequency division among BTSs.
  • time, frequency, time-frequency based coordination based on codebook partitioning is illustrated in Figure 15.
  • the BTSs can perform the operations in a completely centralized way, partially distributed way, or completely distributed way.
  • Different scheduling and coordination algorithms can be used following this principle and the detailed coordination methods will be described in a later section.
  • the codebook is partitioned differently into subsets for different antenna configurations, such as but not limited to, different elements spacing, different antenna geometry, e.g. circular, linear, rectangle, etc.
  • the codebook can be partitioned differently into subsets for different BTSs.
  • the codebook can be partitioned differently into subsets for different users UEs based on their locations, channel conditions, and service requirements such as QoS.
  • the codebook can be partitioned differently into subsets for different QoS requirements. For example, for higher QoS requirements, expand the subset to just reach the required QoS level even though it have certain undesired beam patterns in certain direction that could create some level of interference to neighbor Femtocell BTSs.
  • the codebook based beam forming can also be used not in the beam pattern sense but more from the total channel information sense.
  • the UEs need to feedback channel information related parameters such as channel quality indicator or channel matrix rank or indices of the codebook.
  • the codebook is partitioned into two or more subsets based on the feedback from the neighbor BTSs and the said BTS uses one or more subsets based on the performance requirements.
  • the said BTS will transmit the reference signal on the DL.
  • the neighbor BTSs with the capability of measuring other BTS's DL, as described earlier, will measure the reference signal and calculate feedback parameters if needed, and then send the feedback to the said BTS.
  • the UEs of the said Femtocell also measure the reference signal of the said BTS as well as the neighbor BTSs and provide feedback, which is usually required by the air-interface standard. Based on the feedback from both its UEs and neighbor BTSs, the said BTS would partition the codebook into subsets.
  • the codebook can partition the codebook into those that give better performance to all or some UEs, and those that give less interference to the neighbor BTSs.
  • the said BTS would choose to use the subsets that give better performance to UEs while less interference to the neighbor BTSs.
  • the neighboring BTSs can use the same subset or overlapped subsets in the time-division, frequency-division, or time-frequency division multiplexing fashion.
  • time, frequency, time-frequency based coordination is similar to those illustrated in Figure 15.
  • the BTSs can perform the operations in a completely centralized way, partially distributed way, or completely distributed way. Different scheduling and coordination algorithms can be used following this principle and the detailed coordination methods will be described in a later section.
  • the coordination between the BTSs can be in a completely centralized way, partially distributed way, or completely distributed way.
  • a neighbor list in order to make the coordination more efficient and meaningful, a neighbor list will be formed based on selected criteria, such as the measurement of neighboring BTSs from each BTS.
  • the measurements such as pilot signal strength or the interference level, distance in RF signal strength sense, direction
  • pre-determined thresholds or dynamically calculated thresholds
  • the relative position of the BTSs based the measurement such as DOA
  • the neighbor list or topology can be formed.
  • the neighbor list can also be further divided into multiple levels based on different criteria or different thresholds, if so desired.
  • the neighbor list changes dynamically based on the real-time measurements.
  • the server on the network maintains the neighbor list for all the BTSs, and each BTS maintains and copy of its own neighbor list.
  • the BTSs when the coordination is completely centralized, send the measurements and information required for resource allocations to the network via in-band signaling or out-of-band signaling or a combination of both.
  • the measurements and information include, for example, interference level and direction of the interfered BTSs, bandwidth or data rate requirement for its current applications, channel information for sub-frequency groups or codebook index from the UEs in the interfered areas, average throughput of the BTSs, and so on.
  • the network uses this information to coordinate the beam forming by allocating resources defined in previous embodiments using certain resource management algorithms. This corresponding allocation and coordination information are sent back to each BTSs.
  • the scheduler in each BTS has lower priority than the centralized network resource manager in the sense that the BTS resource management should first allocate those resources specified by the centralized resource manager to the UEs associate with the beam forming operation specified by the centralized control, and then allocate the remaining resources for its UEs based on it scheduling algorithm.
  • Different scheduling and resource management criteria and algorithms can be applied for each BTS.
  • the BTSs when the coordination is partially centralized, send the measurements and information required for resource allocations to the network via in-band signaling or out-of-band signaling or a combination of both.
  • the measurements and information include, for example, interference level and direction of the interfered BTSs, bandwidth or data rate requirement for its current applications, channel information for sub-frequency groups, or codebook index from the UEs in the interfered areas, average throughput of the BTSs, and so on.
  • the network uses this information to coordinate the beam forming by allocating resources defined in previous embodiments using certain resource management algorithms. This corresponding allocation and coordination information are sent back to each BTSs.
  • the BTS uses the information sent back by the centralized network resource manager as input to its scheduler in a way that they would have the same priority as other resources and UEs. Different scheduling and resource management algorithms can be applied here.
  • the BTSs when the coordination is completely distributed, send the measurements and information required for resource allocations to its neighbor BTSs determined by its neighbor list via out-of-band signaling.
  • the information sent to specific neighbor only includes those related to that BTS. For example, interference level and direction of the specific BTS, bandwidth or data rate requirement for its current applications, channel information for sub-frequency groups, or codebook index from the UEs interfered by that BTS, its request for time, frequency group, or time-frequency resources, average throughput of the BTSs, and so on.
  • Each BTS sends relevant information only to those neighbor BTSs on the neighbor list.
  • the receiving neighbor BTSs will accept the request, deny the request or send back a modified version of the request based on predetermined algorithms.
  • One example of the modified version of the request can be granting with less resources than requested or granting the resources but with a shorter time period or a time delay.
  • the neighbor BTS that received the information and requests from other neighbor BTSs shall use the information either as a constraint to its scheduler or as part of the overall input to its scheduler. For example, if the 1st BTS sends the channel information, date rate requests and other necessary information from the UE that is in the interfered area of the 2nd BTS, this channel information can be used as input to the scheduler of the 2nd BTS together with information from UEs in the 2nd BTS. Depending on outcome from the scheduling results, the 2nd BTS decides whether to accept, deny or propose a new resource allocation.
  • the 1st and the 2nd BTSs shall use the following procedure depending on whether the request from the 1st BTS is accepted, denied or modified.
  • the 1st BTS can either renegotiate e.g. send a modified request with less resource requirements, or accept the results as it and run the scheduling and resource allocation algorithm without any constraints.
  • the 2nd BTS will do the same.
  • the 1st BTS treats the granted resources together from other neighbor BTSs as an input to its scheduler while the 2nd BTS should take into account of the resource already granted to the 1st BTS as a constraint to its scheduler.
  • the 2nd BTS will send back a proposed resource grant plan that is based on the available resources determined by its scheduler or resource management entity to the 1st BTS.
  • the 1st BTS can either decide to accept the new proposal or to re-negotiate, i.e. send a modified request with less resource requirements.
  • the 1st BTS will acknowledge to the 2nd BTS.
  • the 1st BTS treats the granted resources together from other neighbor BTSs as an input to its scheduler while the 2nd BTS should take into account of the resource already granted to the 1st BTS as a constraint to its scheduler.
  • DSP digital signal processor
  • ASIC text messaging system specific integrated circuit
  • FPGA field programmable gate array
  • a general-purpose processor can be a microprocessor, but in the alternative, the processor can be any processor, controller, microcontroller, or state machine.
  • a processor can also be implemented as a combination of computing devices, for example, a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.
  • a software module can reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium.
  • An exemplary storage medium can be coupled to the processor such that the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium can be integral to the processor.
  • the processor and the storage medium can reside in an ASIC.
  • Various embodiments may also be implemented primarily in -hardware using, for example, components such as application specific integrated circuits ("ASICs"), or field programmable gate arrays ("FPGAs").
  • ASICs application specific integrated circuits
  • FPGAs field programmable gate arrays
  • ASICs application specific integrated circuits
  • FPGAs field programmable gate arrays
  • ASICs application specific integrated circuits
  • FPGAs field programmable gate arrays

Landscapes

  • Engineering & Computer Science (AREA)
  • Signal Processing (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Power Engineering (AREA)
  • Mobile Radio Communication Systems (AREA)
  • Radio Transmission System (AREA)

Abstract

Dans un système sans fil, un groupe de stations de base (BTS) peuvent être gérées par une entité de gestion de réseau centralisée ou peuvent être auto-organisées par communication l'une avec l'autre par l'intermédiaire d'interfaces radio sans fil ou d'interfaces filaires. Un tel exemple est un système femtocellulaire. Lorsque les BTS utilisent la même fréquence pour émettre et recevoir avec une relativement forte puissance d'émission et lorsqu'elles sont plus proches l'une de l'autre, les performances d'un tel système et le débit ou la qualité de service (QoS) des utilisateurs se dégradent en raison du brouillage entre les BTS et entre les utilisateurs. Une technique d'antenne intelligente peut être utilisée d'une manière coordonnée parmi un groupe de BTS, telles que des femtocellules, pour éviter ou réduire le brouillage ou gérer comment un brouillage se produit afin d'obtenir une amélioration des performances telle qu'un plus haut débit de système ou une meilleure QoS pour des applications individuelles.
PCT/US2009/006458 2009-12-09 2009-12-09 Système et procédé d'amélioration des performances de stations de base à l'aide d'un réseau d'antennes coordonnées WO2011071470A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
CN200980162265.9A CN102612832B (zh) 2009-12-09 2009-12-09 利用协调天线阵列增强基站性能的系统和方法
PCT/US2009/006458 WO2011071470A1 (fr) 2009-12-09 2009-12-09 Système et procédé d'amélioration des performances de stations de base à l'aide d'un réseau d'antennes coordonnées

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/US2009/006458 WO2011071470A1 (fr) 2009-12-09 2009-12-09 Système et procédé d'amélioration des performances de stations de base à l'aide d'un réseau d'antennes coordonnées

Publications (1)

Publication Number Publication Date
WO2011071470A1 true WO2011071470A1 (fr) 2011-06-16

Family

ID=44145806

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US2009/006458 WO2011071470A1 (fr) 2009-12-09 2009-12-09 Système et procédé d'amélioration des performances de stations de base à l'aide d'un réseau d'antennes coordonnées

Country Status (2)

Country Link
CN (1) CN102612832B (fr)
WO (1) WO2011071470A1 (fr)

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2490748A (en) * 2011-05-02 2012-11-14 Inst Information Industry A femtocell management apparatus allocates a resource block according to a request signal and an interference figure
WO2013011383A1 (fr) * 2011-07-15 2013-01-24 Telefonaktiebolaget L M Ericsson (Publ) Sélection de faisceau distribuée pour communication cellulaire
EP2562941A1 (fr) * 2011-08-24 2013-02-27 Samsung Electronics Co., Ltd. Terminal mobile et son procédé de communication, contrôleur de station de base et son procédé de commande et système de transmission multi-coopératif utilisant celui-ci et procédé associé
WO2013151406A1 (fr) * 2012-04-06 2013-10-10 엘지전자 주식회사 Procédé de formation de faisceau coordonnée dans un système d'accès sans fil, et appareil associé
EP2749080A1 (fr) * 2011-12-07 2014-07-02 Telefonaktiebolaget L M Ericsson (publ) Procédé et station de base centrale permettant une gestion d'interférence dans un réseau cellulaire
WO2014149329A1 (fr) * 2013-03-15 2014-09-25 Smartsky Networks LLC Cellules cunéiformes dans un système de communication sans fil
JP2015119361A (ja) * 2013-12-18 2015-06-25 日本電信電話株式会社 通信制御システム及び通信制御方法
EP3172845A4 (fr) * 2014-07-21 2018-04-11 Ruckus Wireless, Inc. Formation de faisceau pour un groupe mimo multiutilisateur
WO2021043420A1 (fr) * 2019-09-06 2021-03-11 Telefonaktiebolaget Lm Ericsson (Publ) Procédés, programme d'ordinateur et nœud de réseau radio pour formation de faisceau à orientation nulle
EP3910879A4 (fr) * 2019-01-30 2022-03-30 Huawei Technologies Co., Ltd. Procédé de communication, appareil de communication et support de stockage

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2015035586A1 (fr) * 2013-09-12 2015-03-19 华为技术有限公司 Procédé, appareil, et station de base, pour l'envoi d'informations
CN105659540B (zh) * 2014-01-29 2020-06-16 华为技术有限公司 无线通信网络和设备
US10142132B2 (en) * 2015-12-30 2018-11-27 Qualcomm Incorporated System and method for reducing interference from neighboring wireless devices
CN113038613B (zh) * 2021-03-01 2022-06-03 中国人民解放军国防科技大学 一种基于图着色问题的三维网络资源分配方法和装置

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5579016A (en) * 1995-09-20 1996-11-26 Trw Inc. Phased array multiple area nulling antenna architecture
US20080075033A1 (en) * 2000-11-22 2008-03-27 Shattil Steve J Cooperative beam-forming in wireless networks
US20090296663A1 (en) * 2008-05-30 2009-12-03 Alcatel-Lucent Via The Electronic Patent Assignment System (Epas) Method of and base station for controlling beam forming in a mobile cellular network

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8085653B2 (en) * 2007-09-08 2011-12-27 Intel Corporation Beamforming with nulling techniques for wireless communications networks

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5579016A (en) * 1995-09-20 1996-11-26 Trw Inc. Phased array multiple area nulling antenna architecture
US20080075033A1 (en) * 2000-11-22 2008-03-27 Shattil Steve J Cooperative beam-forming in wireless networks
US20090296663A1 (en) * 2008-05-30 2009-12-03 Alcatel-Lucent Via The Electronic Patent Assignment System (Epas) Method of and base station for controlling beam forming in a mobile cellular network

Cited By (32)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2490748A (en) * 2011-05-02 2012-11-14 Inst Information Industry A femtocell management apparatus allocates a resource block according to a request signal and an interference figure
GB2490748B (en) * 2011-05-02 2013-11-13 Inst Information Industry Improvements in or relating to femtocell management apparatus
US8694015B2 (en) 2011-05-02 2014-04-08 Institute For Information Industry Network system, femtocell, femtocell management apparatus, resource allocation method and non-transitory machine-redable medium thereof
WO2013011383A1 (fr) * 2011-07-15 2013-01-24 Telefonaktiebolaget L M Ericsson (Publ) Sélection de faisceau distribuée pour communication cellulaire
US8630677B2 (en) 2011-07-15 2014-01-14 Telefonaktiebolaget Lm Ericsson (Publ) Distributed beam selection for cellular communication
US8934903B2 (en) 2011-08-24 2015-01-13 Samsung Electronics Co., Ltd. Mobile terminal and communication method thereof, base station controller and control method thereof, and multi-cooperative transmission system using the same and method thereof
EP2562941A1 (fr) * 2011-08-24 2013-02-27 Samsung Electronics Co., Ltd. Terminal mobile et son procédé de communication, contrôleur de station de base et son procédé de commande et système de transmission multi-coopératif utilisant celui-ci et procédé associé
CN104025656B (zh) * 2011-12-07 2018-08-17 爱立信(中国)通信有限公司 用于蜂窝网络中的干扰管理的方法和中央基站
CN104025656A (zh) * 2011-12-07 2014-09-03 爱立信(中国)通信有限公司 用于蜂窝网络中的干扰管理的方法和中央基站
EP2749080A1 (fr) * 2011-12-07 2014-07-02 Telefonaktiebolaget L M Ericsson (publ) Procédé et station de base centrale permettant une gestion d'interférence dans un réseau cellulaire
US9917682B2 (en) 2011-12-07 2018-03-13 Telefonaktiebolaget Lm Ericsson (Publ) Method and a central base station for interference management in a cellular network
EP2749080A4 (fr) * 2011-12-07 2015-04-15 Ericsson Telefon Ab L M Procédé et station de base centrale permettant une gestion d'interférence dans un réseau cellulaire
US9496929B2 (en) 2012-04-06 2016-11-15 Lg Electronics Inc. Coordinated beamforming method in wireless access system, and apparatus therefor
WO2013151406A1 (fr) * 2012-04-06 2013-10-10 엘지전자 주식회사 Procédé de formation de faisceau coordonnée dans un système d'accès sans fil, et appareil associé
US9503912B2 (en) 2013-03-15 2016-11-22 Smartsky Networks LLC Wedge shaped cells in a wireless communication system
US10972919B2 (en) 2013-03-15 2021-04-06 Smartsky Networks, Llc Wedge shaped cells in a wireless communication system
US9913149B2 (en) 2013-03-15 2018-03-06 Smartsky Networks LLC Wedge shaped cells in a wireless communication system
US9008669B2 (en) 2013-03-15 2015-04-14 Smartsky Networks LLC Wedge shaped cells in a wireless communication system
US9294933B2 (en) 2013-03-15 2016-03-22 Smartsky Networks LLC Wedge shaped cells in a wireless communication system
WO2014149329A1 (fr) * 2013-03-15 2014-09-25 Smartsky Networks LLC Cellules cunéiformes dans un système de communication sans fil
US10257717B2 (en) 2013-03-15 2019-04-09 Smartsky Networks LLC Wedge shaped cells in a wireless communication system
US11838768B2 (en) 2013-03-15 2023-12-05 Smartsky Networks LLC Wedge shaped cells in a wireless communication system
US10623968B2 (en) 2013-03-15 2020-04-14 Smartsky Networks LLC Wedge shaped cells in a wireless communication system
US10771984B2 (en) 2013-03-15 2020-09-08 Smartsky Networks, Inc. Wedge shaped cells in a wireless communication system
US11533639B2 (en) 2013-03-15 2022-12-20 Smartsky Networks LLC Wedge shaped cells in a wireless communication system
JP2015119361A (ja) * 2013-12-18 2015-06-25 日本電信電話株式会社 通信制御システム及び通信制御方法
EP3172845A4 (fr) * 2014-07-21 2018-04-11 Ruckus Wireless, Inc. Formation de faisceau pour un groupe mimo multiutilisateur
US10511358B2 (en) 2014-07-21 2019-12-17 Arris Enterprises Llc Beamforming for a multi-user MIMO group
EP3910879A4 (fr) * 2019-01-30 2022-03-30 Huawei Technologies Co., Ltd. Procédé de communication, appareil de communication et support de stockage
US11895512B2 (en) 2019-01-30 2024-02-06 Huawei Technologies Co., Ltd. Communication method, communication apparatus, and storage medium
WO2021043420A1 (fr) * 2019-09-06 2021-03-11 Telefonaktiebolaget Lm Ericsson (Publ) Procédés, programme d'ordinateur et nœud de réseau radio pour formation de faisceau à orientation nulle
JP7371232B2 (ja) 2019-09-06 2023-10-30 テレフオンアクチーボラゲット エルエム エリクソン（パブル） ヌルステアリングビームフォーミングのための方法、コンピュータプログラムおよび無線ネットワークノード

Also Published As

Publication number Publication date
CN102612832B (zh) 2016-04-20
CN102612832A (zh) 2012-07-25

Similar Documents

Publication Publication Date Title
US8111655B2 (en) System and method of base station performance enhancement using coordinated antenna array
WO2011071470A1 (fr) Système et procédé d'amélioration des performances de stations de base à l'aide d'un réseau d'antennes coordonnées
Shokri-Ghadikolaei et al. Millimeter wave cellular networks: A MAC layer perspective
JP6577057B2 (ja) 通信コントローラを動作させるための方法及び通信コントローラ
JP2023029370A (ja) 方法、システムおよび装置
TWI756605B (zh) 用於處理分散式輸入分散式輸出之無線系統中之都卜勒效應之系統及方法
KR101318851B1 (ko) 협력 빔포밍을 위한 스케줄링 알고리즘들
KR20190061007A (ko) 연속 프리코딩에 의한 송신 특성들의 동적 조정
WO2016143238A1 (fr) Procédé de commande de couverture, appareil station de base, système de radiocommunication, et support de stockage non transitoire lisible par ordinateur contenant un programme de commande de station de base
US20220263240A1 (en) Interference aware adaption of antenna radiation patterns
US20110171955A1 (en) UE initiated frequency partitioning based CoMP scheme for downlink cellular communications
CN110612694B (zh) 用于mimo通信的预编码器资源组分配方法
US11729757B2 (en) Power level determination for transmission of reference signals
US9872305B2 (en) Optimized cellular transmission scheduling based on knowledge of interference-mitigation capabilities in neighbor cell
CN110754044B (zh) 用于上行链路覆盖自适应的系统和方法
CN111344958A (zh) 用于ue请求信道状态信息参考信号(csi-rs)或探测参考信号(srs)的方法
US20180175992A1 (en) A Wireless Device, A Radio Network Node, And Methods Therein
JP2021502741A (ja) 非プリコーダ行列インジケータ（ｐｍｉ）チャネル状態情（ｃｓｉ）フィードバックのためのポートインデクスをシグナリングする方法及び装置
KR20170085989A (ko) 간섭을 제어하기 위한 장치 및 방법
US11750420B2 (en) Tone placement for reference signal optimization
US20230318690A1 (en) Iterative transmit refinement
CN114731175A (zh) 无线通信网络中的子带预编码信令
WO2016054819A1 (fr) Procédé et dispositif de transmission de signaux, et système
US10979108B2 (en) Interference free geographical zonal mapping utilizing slow varying channel covariance matrix
Park et al. Multicell cooperative scheduling for two-tier cellular networks

Legal Events

Date Code Title Description
WWE Wipo information: entry into national phase

Ref document number: 200980162265.9

Country of ref document: CN

121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 09852118

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 09852118

Country of ref document: EP

Kind code of ref document: A1