EP1504535A1 - Appareil et procede associe permettant de faciliter la selection du poids d'une antenne a l'aide d'une approximation de gradient de perturbation deterministe - Google Patents

Appareil et procede associe permettant de faciliter la selection du poids d'une antenne a l'aide d'une approximation de gradient de perturbation deterministe

Info

Publication number
EP1504535A1
EP1504535A1 EP03728913A EP03728913A EP1504535A1 EP 1504535 A1 EP1504535 A1 EP 1504535A1 EP 03728913 A EP03728913 A EP 03728913A EP 03728913 A EP03728913 A EP 03728913A EP 1504535 A1 EP1504535 A1 EP 1504535A1
Authority
EP
European Patent Office
Prior art keywords
perturbation
communication
communication station
perturbation vector
vector
Prior art date
Legal status (The legal status 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 status listed.)
Withdrawn
Application number
EP03728913A
Other languages
German (de)
English (en)
Other versions
EP1504535A4 (fr
Inventor
Balaji Raghothaman
Thomas R. Derryberry
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Nokia Oyj
Original Assignee
Nokia Oyj
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
Priority claimed from US10/146,159 external-priority patent/US6745009B2/en
Priority claimed from US10/334,045 external-priority patent/US6842632B2/en
Application filed by Nokia Oyj filed Critical Nokia Oyj
Publication of EP1504535A1 publication Critical patent/EP1504535A1/fr
Publication of EP1504535A4 publication Critical patent/EP1504535A4/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q3/00—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system
    • H01Q3/26—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system varying the relative phase or relative amplitude of energisation between two or more active radiating elements; varying the distribution of energy across a radiating aperture
    • 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
    • H04B7/0621—Feedback content
    • H04B7/0634—Antenna weights or vector/matrix coefficients
    • 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
    • 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
    • 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
    • H04B7/0641—Differential feedback

Definitions

  • the present invention relates generally to a manner by which to select antenna- weightings at a sending station that utilizes transmit diversity. More particularly, the present invention relates to apparatus, and an associated method, by which to utilize a perturbation gradient approximation technique in the selection of the antenna weightings. Improved antenna-weighting selection accuracy is provided as a long-term covariance matrix of a channel upon which a communication signal is sent is tracked, instead of merely tracking a short-term fading process. And, the amount of feedback needed in the effectuation of the antenna- weight selection is independent of the number of transmit antennas utilized by the sending station. Background of the Invention
  • Communication of information is an endemic necessity of modern society. Communication of information is effectuated through operation of a communication system. Information is communicated between a sending station and a receiving station by way of a communication channel. The sending station, if necessary, converts the information into a form to permit its communication upon the communication channels. And, the receiving station, if necessary, operates upon detected indications of the information to permit operations to be performed thereupon to recover the information.
  • An exemplary communication system is a radio communication system, a radio communication system, the communication channel is defined upon a radio link extending between the sending and receiving stations.
  • Communication systems implemented as radio communication systems are sometimes of reduced costs, relative to wire line counterparts.
  • radio communication systems are amenable to implementation as mobile communication systems since radio links, rather than fixed, wire line connections, are utilized upon which to define communication channels used to communicate the information.
  • a cellular communication system is exemplary of a radio communication system that has achieved significant levels of usage.
  • Cellular communication systems have been installed throughout significant parts of the populated portions of the world.
  • Various cellular communication standards have been promulgated, setting forth the operational parameters of different types of cellular communication systems.
  • a cellular communication system includes a fixed network infrastructure that includes a plurality of fixed-site base transceiver stations.
  • the fixed-site base transceiver stations are positioned at spaced-apart locations throughout a geographical area that is to be encompassed by the communication system.
  • Each of the base transceiver stations defines an area, referred to as a cell, from which the cellular communication system derives its name.
  • the fixed network infrastructure of which the base transceiver stations form portions is coupled to a core network, such as a packet data backbone or public-switched, telephonic network.
  • a core network such as a packet data backbone or public-switched, telephonic network.
  • Communication devices such as computer servers, telephonic stations, etc. are, in turn, coupled to the core network, or elsewhere, and are capable of communication by way of the network infrastructure and the core network.
  • Portable transceivers communicate with the base stations by way of radio links forming portions of the electromagnetic spectrum.
  • Use of the cellular communication system is permitted, typically, pursuant to a service subscription, and users, referred to as subscribers, communicate by way of the cellular communication system through utilization of the mobile stations.
  • -information communicated upon a radio link is susceptible to distortion as a result of non-ideal communication conditions.
  • Other communication systems are analogously non- ideal, and communication of information in such other communication systems analogously also is susceptible to distortion.
  • the distortion causes values of the information delivered to a receiving station to differ with the corresponding values of the information, when transmitted by the sending station. If the distortion is significant, the informational content of the information cannot be accurately recovered at the receiving station.
  • Fading caused by multi-path transmission distorts information communicated upon a communication channel. If the communication channel exhibits significant levels of fading, the informational content of the information might not be able to be recovered.
  • Space diversity for instance, is sometimes utilized. Space diversity is created through the use, at a sending station, of more than one transmit antenna transducer from which information is transmitted. Spatial redundancy is provided therefrom. The antenna transducers are typically separated by distances great enough to ensure that the information communicated by respective antenna transducers fades in an uncorrelated manner. And, receiving stations sometimes also utilize more than one receive antenna transducer, also typically separated by appropriate separation distances.
  • MIMO Multiple-Input, Multiple-Output
  • Communications in an MLVIO system provide the possibility that higher overall capacity of the system, relative to conventional systems can be achieved. Increased number of users are able to be serviced, or more data throughput is capable of being provided for each user.
  • the advantages provided through the use of space diversity are further enhanced if the sending station is provided with information about the state of the interface, interfacing the sending and receiving stations, i.e., the communication channel.
  • a sending station is not able to measure channel characteristics of the communication channel directly. Such measurements are possible only at a receiving station. In two-way communication systems, measurements made at the receiving station can be returned to the sending station to provide an indication to the sending station of the channel characteristics.
  • Communication systems that provide this type of information to a multiple-antenna sending station are referred to as being systems that provide closed loop transmit diversity.
  • Communication channels extending from the network infrastructure of a cellular communication system to a mobile station are sometimes referred to as being down link, or forward link, channels.
  • channels extending from the mobile station back to the network infrastructure are sometimes referred to as being uplink, or reverse link, channels.
  • the feedback information returned to the sending station, here at the network infrastructure, from the receiving station, here a mobile station, is used to select values of antenna weightings.
  • the weightings are weighting values by which information signals provided to separate ones of the antenna transducers are weighted prior to their communication upon a communication channel to the mobile station.
  • a goal is to weight the information signals applied to the antenna transducers in manners best to facilitate communication of the information to the receiving station.
  • the values of the antennas weightings approach a conjugate of the subspace spanned by down-link channel covariance matrix. Estimation of the antenna weightings can be formulated as a transmission subspace tracking procedure. Several closed loop transmit diversity procedures are utilized. TxAA, Eigenbeam Former, and other techniques are sometimes utilized.
  • a TxAA procedure fails to take into account a long-term covariance matrix of the communication channel in the selection of the antenna weightings.
  • use of an Eigenbeam former technique is dependent upon the number of antenna transducers of the sending station. When the number of antenna transducers increases, the complexity of such a technique increases rapidly.
  • the present invention accordingly, advantageously provides a manner by which to utilize a perturbation gradient approximation technique in the selection of antenna weightings at a sending station that utilizes transmit diversity.
  • apparatus and an associated method, is provided by which to select the antenna- weightings at the sending station that utilizes transmit diversity.
  • a long-term covariance matrix of the communication channel is tracked instead of merely tracking a short-term fading process.
  • the amount of feedback needed for effectuation of the antenna weighting selection is independent of the number of transmit antennas utilized by the sending station. Also, a user-specific pilot signal is not needed for operation. So, the method, and apparatus, is implementable in any of many different types of high data-rate systems, not merely systems that utilize a pilot signal.
  • a deterministic perturbation gradient approximation procedure is carried out to facilitate the antenna weighting values to be utilized at a sending station that utilizes space diversity.
  • the approximation technique facilitates optimization of the selection of the antenna weighting values, thereby to optimize the communications between a sending station and a receiving station.
  • a perturbation vector is selected at the sending station for communication upon the communication channel to the receiving station.
  • the perturbation vector is selected in a selected order, selected from a selected set of vectors.
  • the vectors are each formed of vector values.
  • the antenna weightings of the antenna transducers of the sending station are perturbed in a first manner during a first portion of a time period and in a second manner during a second portion of a time period.
  • the antennas weightings are perturbed by the perturbation vector in a positive direction. And, during a second half of the time slot, the perturbation vector is applied to the antenna weightings to perturb the weightings in a negative direction.
  • the receiving station that receives the information communicated by the sending station upon the communication channel measures power levels of received signals containing the information communicated by the sending station. Separate power level measurements are made during the first half and the second half of the time slot. Differences between the power levels measured during the separate halves of the time slot are determined. And, an indication of the values of the calculated differences are returned to the sending station.
  • the sending station detects delivery of the indications of the values of the calculated differences made at the receiving station and utilizes such indications to adjust the antenna weightings by which subsequently to weight information signals that are sent by the sending station to the receiving station.
  • the deterministic perturbation gradient approximation technique is utilized in a cellular communication system having a base transceiver station that utilizes space diversity. Closed loop transmit diversity is provided to optimize selection of antenna weightings by which to weight down link signals that are communicated to the mobile station by the base transceiver station. Perturbation vectors are applied to the antenna weighting elements in positive and negative directions during separate portions of a time period. Weighted signals are sent by the base transceiver station to the mobile station and are detected thereat. The mobile station measures power levels of the signals detected thereat during the first and second portions of a time slot and returns values of differences in the power levels measured during the first and second portions of the time slot to the base transceiver station.
  • the values returned to the base transceiver station are used to adjust the antenna weightings at the base transceiver station. Closed-loop transmit diversity is thereby provided. Because deterministic perturbation gradient approximation techniques are utilized, a long-term covariance matrix is tracked and utilized upon which to select the antenna weightings. And, the antenna weighting selection is independent of the number of transmit antennas utilized by the base transceiver station, or other sending station.
  • apparatus, and an associated method for a communication system having a first communication station and a second communication station.
  • the first communication station communicates a communication signal to the second communication station.
  • the communication signal is weighted at a first weighting element of the first communication station by a first weighting element of the first communication station by a first antenna weight.
  • the communication signal is weighted at least at a second weighting element of the first communication station with at least a second antenna weight. Optimization of selection of the first and at least second antenna weights is facilitated.
  • a perturbation vector selector is coupled to the first communication station. The perturbation vector selector selects at least a first set of perturbation vector values to form at least a first selected perturbation vector.
  • a perturbation vector applicator is coupled to the perturbation vector selector.
  • the perturbation vector applicator applies the perturbation values forming the at least the first selected perturbation vector to the first and at least second weighting elements.
  • the perturbation values applied to the first and at least second weighting elements are at least in part determinative of the first and at least second antenna weights.
  • apparatus, and an associated method for a communication system having a first communication station, a second communication station, and at least a third communication station.
  • the first communication station and the third communication station selectably together communicate a communication signal to the second communication station.
  • the communication signal is weighted at a first weighting element of the first communication station by a first antenna weight.
  • the communication signal is weighted at least at a second weighting element of the first communication station with at least a second antenna weight.
  • the communication signal is selectably weighted at least at a third weighting element of the third communication station. Optimization of selection of the first, second, and at. least third antenna weights is facilitated.
  • a perturbation vector selector is coupled to the first communication station and to the third communication station.
  • the perturbation vector selector selects at least a first set of perturbation vector values to form at least a first selected perturbation vector.
  • a perturbation vector applicator is coupled to the perturbation vector selector.
  • the perturbation vector applicator selects application of the perturbation values forming the at least the first selected perturbation vector to the first and at least second weighting elements of the first communication station.
  • the perturbation vector applicator further selectably selects application of the perturbation values forming the at least the first perturbation vector to the third antenna weighting element.
  • the perturbation values that are applied to the first, second, and, selectably, at least third weighting element are at least in part determinative of the first and at least second antenna weights.
  • Figure 1 illustrates a functional block diagram of a communication system in which an embodiment of the present invention is operable to facilitate selection of optimal antenna weightings by which to weight signals communicated during operation of the communication system.
  • Figure 2 illustrates a representation of the deterministic perturbation gradient approximation technique utilized during operation of an embodiment of the present invention.
  • Figure 3 illustrates a representation, similar to that shown in Figure 2, of the deterministic perturbation gradient approximation technique utilized during operation of another embodiment of the present invention.
  • Figure 4 illustrates a method flow diagram listing the method of operation of an embodiment of the present invention.
  • Figure 5 illustrates a functional block diagram, similar to that shown in Figure 1, but here representative of the communication system during a handoff process.
  • Figure 6 illustrates a functional block diagram of a portion of the communication system shown in Figure 5.
  • Figure 7 also illustrates a functional block diagram of a portion of the communication system shown in Figure 5. Detailed Description
  • a radio communication system shown generally at 10, provides for 2-way radio communications between two separately-positioned communication stations interconnected by way of radio channels.
  • a first of the communication stations forms a base transceiver station (BTS) 12 of a cellular communication system.
  • BTS base transceiver station
  • the second of the communication stations forms a mobile station 14, also operable in a cellular communication system.
  • the radio communication channels are defined upon radio links, here forward-link channels 16 and reverse-link channels 18.
  • Information sent to the mobile station is communicated by the base transceiver station upon the forward-link channels 16.
  • information originated at the mobile station 14 for communication to the base transceiver station is communicated upon reverse link channels 18.
  • the communication system 10 is exemplary of a cellular communication system constructed pursuant to any of several different cellular-communication standards.
  • the base transceiver station and mobile station are exemplary of devices operable in a CDMA (Code-Division, Multiple-Access) communication scheme, such as a 3G-CDMA (third generation, CDMA) communication standard.
  • CDMA Code-Division, Multiple-Access
  • 3G-CDMA third generation, CDMA
  • Operation of an embodiment of the present invention is, of course, analogously also operable in other types of cellular communication systems as well as other types of communication systems in which closed- loop transmit diversity, can advantageously be utilized.
  • the base transceiver station forms part of a radio access network that also includes a radio network controller (KNC) 22. And, the radio network controller, in turn, is coupled to a mobile switching center (MSC) 24 and a gateway (GWY) 26.
  • the mobile switching center and gateway also form portions of the radio access network.
  • the mobile switching center is coupled to a public-switched telephonic network (PSTN) 28.
  • PSTN public-switched telephonic network
  • the gateway is coupled to a packet data network (PDN) 32, such as the internet backbone.
  • PDN packet data network
  • a correspondent node (CN) 34 is shown to be coupled to the packet data network and to the PSTN.
  • the correspondent node is exemplary of a data source or a data destination from which, or to which, information is routed during operation of the communication system.
  • the base transceiver station 12 includes both a receive part, represented by the receive circuitry 36, and a transmit part, represented by transmit circuitry 38.
  • a forward link signal to be communicated by the base transceiver station to the mobile station is converted into a form to permit its communication upon a forward link channels 16 by the transmit circuitry.
  • closed-loop feedback information is returned by the mobile station to the base transceiver station by way of a reverse link channel 18.
  • the mobile station 14 also includes a receive portion, represented by the receive circuitry 40 and a transmit part, represented by the transmit circuitry 42.
  • the receive circuitry operates to receive, and operate upon, forward-link signals transmitted by the base transceiver station upon forward-link channels 16.
  • the transmit circuitry 42 operates to transmit reverse-link signals upon reverse-link channels 18 to the base transceiver station.
  • both the base transceiver station and the mobile station include the multiple antenna transducers, and the base transceiver station-mobile station combination forms an MBVIO (multiple-input, multiple-output) system.
  • the base transceiver station includes N antenna transducers 44-1 through 44-N.
  • the mobile station includes M antenna transducers, antenna transducers 46-1 through 46-M.
  • the antenna transducers 44 and 46 are, here, coupled to both of the transmit and receive circuitries of the base transceiver station and mobile station, respectively.
  • the transmit circuitry 38 includes an encoder 52 that encodes data provided thereto by way of the line 54 to form encoded data on the line 56.
  • the line 56 is coupled to a first input terminal of an up-mixer 58 and, an up-mixing signal v(t), is applied to a second input terminal of the up-mixer by way of the line 62.
  • An up-mixed signal is generated on the line 64.
  • the line 64 includes separate branches for applying the up-mixed signal to the separate antenna transducers 44.
  • Weighting elements 66 and 68 are positioned in-line in the separate branches of the line 64. That is to say, a branch of the line 64 is coupled to an input terminal of the weighting element 66, and a second branch of the line 64 is coupled to an input terminal of the weighting element 68.
  • Lines 72 and 74 are also coupled to the antenna weighting elements 66 and 68, respectively. Values generated on the lines 72 and 74 are determinative of the weightings applied to the up-mixed signals. Once the signals are weighted, the signals are applied to the antenna transducers to be transduced thereat. Additional up-mixing, and other, operations are performed upon the weighted signals prior to application to the antenna transducers.
  • the base transceiver station further includes apparatus 78 of an embodiment of the present invention.
  • the apparatus 78 adjusts the values of the weightings generated on the lines 72 and 74 and applied to the weighting elements 66 and 68, respectively, in manners that facilitate optimal antenna weighting selection pursuant to a closed loop transmit diversity scheme of an embodiment of the present invention.
  • the elements forming the apparatus are functionally represented and are implementable in any desired manner, such as by algorithms executable by processing circuitry.
  • the apparatus includes a perturbation vector selector 82 that operates to select perturbation vectors formed of vector values retrieved from a perturbation vector buffer 84.
  • the perturbation vectors selected by the selector 82 are provided to a perturbation vector applicator 84 applies the perturbation vector to the antenna weighting elements 66 and 68 in selected manners.
  • the perturbation vectors perturb the weightings of the antenna weighting elements and, in turn, the values of the signals transduced by the antenna transducers 44.
  • Forward-link signals generated on the forward- link channels 16, weighted with the perturbation vectors are delivered to the mobile station 14.
  • Signals detected by the antenna transducers 46 are transduced into electrical form, provided to the receive circuitry 40 and operated upon thereat.
  • the mobile station also includes apparatus 78 of an embodiment of the present invention.
  • the apparatus 78 positioned at the mobile station includes a detector 88 that operates to detect, and measure, indications of the perturbations of the power levels of the signal generated by the base transceiver station and communicated on the forward-link channels 16.
  • indications of the power levels of the signals are measured, and indications thereof are provided to the transmit circuitry for transmission back to the base transceiver station.
  • indications of the detections made by the detector are used to adjust the subsequent antenna weightings by which the weighting elements 66 and 68 to weight the signals applied thereto.
  • the apparatus 78 operates to provide a deterministic perturbation gradient approximation that provides tracking of long-term feedback.
  • the deterministic perturbation gradient approximation technique utilized by the apparatus 78 of an embodiment of the present invention builds upon stochastic perturbation gradient approximations (SPGAs). Optimization techniques sometimes utilize a procedure referred to as gradient descent.
  • gradient descent involves adaptively converging to a point in a vector space, corresponding to the global minimum (or maximum) of a cost function defined on the space. At each iteration of the adaptation, an estimate of the gradient of the cost function is formed, and the estimate of the optimal vector is revised such that it moves in the direction of the gradient vector. This process can be visualized in three dimensions involving a 2-D vector space, as moving closer to the bottom of the cost-function bowl at each iteration.
  • the most widely used gradient search technique is the stochastic gradient search, which is applied in the Least Mean Squares (LMS) algorithm for adaptive finite impulse response (FIR) filtering.
  • LMS Least Mean Squares
  • FIR finite impulse response
  • One of the features of adaptive time domain FIR filtering is that, in most such problem formulations, an input stochastic vector process is acting upon the filter, which is of the same dimensionality as the filter, and can thus be used to estimate the cost function gradient vector.
  • One such method is called the simultaneous stochastic perturbation gradient approximation technique, in which, at each iteration, the effect of a stochastic perturbation on the cost function is studied, and based on this effect, the estimate of the optimal vector is moved toward or away from the direction of the perturbation vector.
  • the stochastic perturbation technique mentioned above has been applied to the problem of transmission subspace tracking for closed loop transmit diversity and MBVIO.
  • dedicated pilots are used, which carry the perturbed weights based on which the cost function is estimated.
  • the dedicated pilots are also used to coherently demodulate the received signal, since the average of the dedicated pilot over two slots provides the weighted composite channel estimate necessary for coherent demodulation.
  • Another disadvantage of the existing SPGA technique is that the dedicated pilots are usually transmitted with the same power as the traffic signal, which is quite low when compared to the user-non-specific antenna pilots, henceforth referred to as common pilots. This fact leads to a degraduation in the channel estimate and hence the performance of the link as such.
  • a possible method for increasing the reliability of the channel estimate is to use a combination of the channel estimates from the common pilots along with an estimate of the weights applied at the transmitter. These weights can, in fact be known to the mobile station if the same set of random perturbation vectors applied at the transmitter can be replicated at the mobile receiver. This involves operating a complex random number generator at both the base station and the mobile station in a synchronized manner. The complexity and synchronization issues make this an undesirable alternative.
  • a deterministic perturbation is proposed, which makes it unnecessary to operate two synchronized random vector generators.
  • a method of extracting the cost function from the traffic signal itself is proposed, rendering a user-specific pilot unnecessary.
  • the aim of the algorithm is to estimate the optimal antenna weights w for transmission.
  • h pik is a M-length vector representing the fading channel coefficients at time k, from the M-antenna transmitter to the p th antenna of a receiver with N antennas, with L paths from each transmit antenna to each receive antenna.
  • the received signal power is given by i* 3 tne channel covariance matrix.
  • u 0 is referred to as the principal eigenvector, or alternately the principal component of k
  • c is a real scalar quantity.
  • the covariance matrix is assumed to be constant over the period in which the perturbations are performed.
  • E[c ⁇ w k ] the quantity of the perturbation is composed of randomly generated complex vectors
  • E[.] refers to the expectation operator
  • sgn(c) the quantity of the perturbation is composed of randomly generated complex vectors
  • sgn(c) the quantity of the perturbation is composed of randomly generated complex vectors
  • sgn(c) instead of c. This is because sgn(c) can be visualized a highly quantized form of c, with 1-bit quantization.
  • sgn(c) c + ⁇ , where ⁇ is the quantization noise, usually assumed to be uncorrelated with the statistics of c.
  • a primary idea is to use a set or predetermined vectors for the perturbation, and cycle through them.
  • the test of whether a state of vectors from a complete perturbation set for our purposes is that the condition
  • any arbitrary vector in the complex space can be represented as a linear sum of vectors in Q M using real coefficients.
  • any orthonormal set of vectors can be used to form a perturbation set for transmission subspace tracking.
  • orthonormal sets are the set of Discrete Fourier Transform (DFT) vectors, or the Discrete Cosine Transform (DCT) vectors.
  • the convergence of the DPGA method can be shown to be similar to that of the stochastic perturbation approach.
  • the randomness of the perturbation has been stated as an essential condition for convergence.
  • One of the considerations seems to be that a deterministic perturbation will lead to a biased estimate.
  • Another is that only a random perturbation will lead to guaranteed convergence to the global minimum.
  • the iterative algorithm will be trapped in a local minimum only in the condition that the cost function surface is flat in all the directions pertaining to each of the perturbation vectors, at that local minimum. The probability of such an occurrence is probably small, especially in a time varying fading channel environment.
  • the quantity g t from (7) must be obtained at the mobile receiver.
  • One method is to transmit a pilot signal weighted with the perturbed weights. This pilot will be specific to the user, and hence requires additional power allocated to the user. Note that the traffic signal itself will be weighted with the weight vector that was obtained by adaptation at the previous iteration, i.e., w , while the dedicated pilot will e weighted with w k + ⁇ Aw] and w k - ⁇ Aw] in succession.
  • An alternative approach used in an exemplary implementation, is to use the traffic channel itself to obtain the cost function.
  • the traffic signal is weighted using the perturbed weights.
  • the term ° r tne ener ⁇ y of the transmitted symbol becomes expendable when using constant modulus schemes like QPSK, 8PSK, but it has to be taken into account multilevel schemes like 16-QAM.
  • the quantity sgn(c) can be estimated from (7).
  • the only disadvantage of the usage of the traffic channel itself to aid the adaptation as described above, is that the actual weights applied are always perturbed from the values dictated by the adaptation.
  • the weights as prescribed by the adaptation algorithm are W k , but the actual weights used are w e or w 0 . But since ⁇ is a small quantity, the effect of this perturbation on the performance of the algorithm is insignificant.
  • Figure 2 illustrates the apparatus 78, showing exemplary operation thereof to optimize the antenna weightings of the weighting element to optimize communications on the forward link to the mobile station.
  • Elements in the figure shown at the left-side (as shown) of the line 92 are representative of operations performed at the base transceiver station. And, functions shown at the right-side (as shown) of the line 92 are performed at the mobile station 14.
  • the weighting values of the antenna weightings represented by a weight vector, is initialized to a zero value, or a small complex vector quantity known to the mobile station as well as the base transceiver station.
  • a perturbation vector is selected in a pre-determined order from a predetermined set of vectors at a time-slot k.
  • the transmit weights are perturbed in a positive direction to generate w e and forward-link, traffic-channel are weighted through the perturbed weights before being transduced by the antenna transducers 44.
  • Such operations are represented by the function 96.
  • the transmit weights are perturbed in the negative direction to generate w 0 , and forward-link traffic-channel signals are weighted through the perturbed weights before being transduced by the antenna transducers 44.
  • Such operations are indicated by the function 98.
  • the values are delayed, indicated by the operator D "1 indicated by the block 102.
  • the apparatus 78 operates to measure the power levels of the receive signal during both halves of the time slot k.
  • the received power P e is obtained after correcting for the amplitudes of the modulated transmit symbols. And, such value is operated upon by the operator D "1 indicated by the function 106.
  • the receive power P 0 is obtained, indicated by the function 108. Then, a difference therebetween is determined and a single bit representation thereof is determined, indicated by the function 112, and returned as feedback to the base transceiver station.
  • Figure 3 illustrates the apparatus 78, showing exemplary operation of another embodiment of the present invention by which to facilitate selection of the weighting values applied to the weighting elements of a sending station to optimize communications on the forward link to the mobile station.
  • the delays, represented by the functions 102 and 106, associated with operation of the embodiment shown in Figure 2 are obviated as, here, the perturbations are performed at the mobile station.
  • elements in the figure shown at the left-side (as shown) of the line 92 are representative of operations performed at the base transceiver station. And, again, functions shown at the right-side (as shown) of the line 92 are performed at the mobile station 14.
  • the function 116 represents the generation of pilot signals by the base transceiver station for communication to mobile stations, such as the mobile station 14.
  • the function 118 at the mobile station is representative, as described herein, formation of values of the vectors R. Indications of the values generated by the function R are provided to the functions P e and P 0 122 and 124.
  • the functions 122 and 124 are also coupled to the function 94, here positioned at the mobile station.
  • the function 94 is maintained in synchronization with a corresponding function 94 maintained at the base transceiver station.
  • the function 94 is representative of selection of a perturbation vector, selected in a pre-determined order from a predetennined set of vectors at time-slot k.
  • the functions 122 and 124 are provided to a difference function 112 that operates to determine a single-bit representation of the differences between the values determined at the functions 122 and 124, respectively.
  • the difference is returned to the base transceiver station and used to adjust the weighting values, indicated by the block 126, by which the weighting values of the antenna weightings are weighted.
  • Figure 4 illustrates a method, shown generally at 134 representative of the method of operation of an embodiment of the present invention.
  • the method facilitates optimization of selection of antenna weights by which to weight signals generated in a radio communication system that utilizes closed-loop transmit diversity.
  • At least a first selected perturbation selector formed of perturbation values is selected.
  • the at least the first selected perturbation vector is applied to the antenna weighting elements of a sending station.
  • the communication signal once weighted by the first and at least second antenna weights, is sent to the second communication station.
  • a manner is provided by which to utilize a single-bit feedback value to select the antenna weightings that the antenna weighting elements weight send signals.
  • Improved accuracy is provided as a long-term covariance matrix is utilized instead of merely tracking a short-term fading process.
  • the amount of feedback needed to effectuate the selection of the antenna weightings is independent of the number of transmit antennas utilized by the sending station.
  • a soft handoff process is used, e.g., in a cellular communication system operable pursuant to the aforementioned 3G-CDMA communication standard, as well as other communication standards.
  • a mobile station simultaneously receives data, upon a traffic channel, transmitted by multiple, that is, two or more, base stations.
  • An active set is maintained by, or otherwise associated with, the mobile station. The active set lists neighboring base stations from which signals of signal levels, such as signal strengths, are better than a selected threshold.
  • base stations transmit pilot signals.
  • the signal strengths of the pilot signals transmitted by selected neighboring base stations are measured by the mobile station.
  • the mobile station reports an indication of such determination to the network.
  • the base station from which the pilot signal is transmitted becomes part of the active set associated with the mobile station. Traffic data that is to be communicated to the mobile station is communicated by all of the base stations of the active set associated with the mobile station, hi analogous manner, base stations are selectably removed from the active set when the pilot signals generated thereat fall beneath the selected threshold.
  • traffic data can continue to be communicated with the mobile station as successive ones of the base stations form the active set associated with the mobile station.
  • a soft handoff process is said to occur.
  • the deterministic perturbation gradient approximation technique facilitates antenna weighting selection accuracy when one or more of the base stations involved in a handoff process utilizes antenna weighting.
  • the deterministic perturbation gradient approximation technique Prior to, and subsequent to, the handoff process, the deterministic perturbation gradient approximation technique is carried out as described previously, with respect to the embodiments shown in Figures 1-4. And, during the handoff process, the deterministic perturbation gradient approximation technique is also used, here in which the antenna weighting perturbations are applied to the antenna weighting elements of the respective ones of the base stations.
  • Figure 5 shows a radio communication system, analogous to the communication system shown in Figure 1, and here again shown generally at 10.
  • the communication system again includes a network part with which a mobile station 14 communicates by way of forward and reverse link channels.
  • the network part of this embodiment is shown to include two base stations 12, here represented at 12-1 and 12-2.
  • the base stations are formed of functional elements substantially identical to the functional elements previously shown in Figure 1 to form the base station 12 described with respect to Figure 1.
  • Elements shown in Figure 1 that correspond to the elements of the base stations 12-1 and 12-2 are commonly- referenced. And, description of operation of such commonly-referenced elements can be found with respect to the earlier description of Figure 1.
  • the base stations 12-1 and 12-2 are representative of base stations that form part of the active set during a handoff process. Additional base stations 12 can also form part of the active set, and Figure 5 can correspondingly show such additional base stations.
  • the apparatus 78 is shared between the base stations 12-1 and 12-2. As the apparatus 78 is functionally represented, the apparatus is again implementable in any desired manner, with elements thereof shared by the base stations 12-1 and 12-2, located at one of the base stations, located separate from the base stations, or distributed therebetween.
  • the perturbation selector when data is transmitted to the mobile station by both of the base stations 12-1 and 12-2, the perturbation selector generates values on the lines 72 and 74 to perturb the antenna weightings of the antenna elements of both of the base stations. That is to say, during the handoff process, the perturbation vector values are applied to additional numbers of antenna weighting elements. Modification of the deterministic perturbation gradient algorithm is made by increasing the lengths of the perturbation vectors that are used, and the size of the vector set from which the perturbation vectors are determinisitically selected is also increased.
  • the buffer 84 at which the perturbation vectors are buffered is here shown to include a first set 84-1 and a second set 84-2.
  • the first set is of a first size and of vectors of first lengths.
  • the second set is of a second size and of vectors of second lengths.
  • the vectors are selected from the second set, and values thereof are applied to the antenna weighting elements of both of the base stations.
  • Figure 6 illustrates portions of the base station 12-1, during operation of the communication system in non-handoff conditions.
  • the apparatus 78 generates values on the lines 72 and 74 that are applied to the antenna weighting elements 66 and 68.
  • the perturbation vectors are selected from the first set 84-1.
  • Figure 7 illustrates portions of the base station 12-1 and 12-2 during operation of the communication system during a handoff condition.
  • the apparatus 78 generates values on the lines 72 and 74 that extend to the antenna weighting elements of the separate base stations 12-1 and 12-2.
  • the perturbation vectors are selected from the second set 84-2.
  • the perturbation vectors are rotated amongst this set, and the feedback remains the same as that used during non-handoff conditions.
  • the active set of the mobile station is increased to include the additional base station, and a resetting and expansion of the perturbation vector set commences.
  • the perturbation algorithm continues with the new, longer-weight vector, hi one implementation, the perturbation starts from the first vector of the expanded set.
  • the first (P-l)M elements of the expanded weight vector have aheady been adapting and have converged to some value, pursuant to operations during non-handoff conditions.
  • the soft handoff process starts, the elements start adapting to re-converge to a new optimum, and the additional elements commence adaptation.
  • the order in which the weights are applied to the antenna weighting elements is unambiguous.
  • the information is derived, for instance, from the order of the base stations 12 in the active set buffer, along with knowledge of the number of antennas in each base station. Such information is available to all of the base stations as well as the mobile station.

Landscapes

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

Abstract

La présente invention concerne un appareil, ainsi qu'un procédé associé, permettant de faciliter la sélection de facteurs de pondération optimaux d'une antenne au moyen desquels il est possible de pondérer des signaux envoyés dans un système de communication qui utilise la diversité de transmission en boucle fermée. On utilise une technique d'approximation du gradient de perturbation déterministe dans laquelle des vecteurs de perturbation sont sélectionnés (136) par un sélecteur et appliqués, par un applicateur, à des éléments de pondération d'antenne. Un ensemble sélectionné de vecteurs de perturbation est appliqué aux éléments de pondération d'antenne dans une direction positive et dans une direction négative (138). Un détecteur situé au niveau d'une station de réception mesure, en les disassociant, les signaux communiqués, une fois pondérés à l'aide des vecteurs de perturbation. Une valeur de rétroaction à un seul bit est renvoyée vers la station d'émission, et les pondérations d'antenne sont réglées (142) de manière appropriée. Ladite technique est utilisée au cours d'états de non transfert intercellulaire et au cours d'états de transfert intercellulaire.
EP03728913A 2002-05-15 2003-05-15 Appareil et procede associe permettant de faciliter la selection du poids d'une antenne a l'aide d'une approximation de gradient de perturbation deterministe Withdrawn EP1504535A4 (fr)

Applications Claiming Priority (5)

Application Number Priority Date Filing Date Title
US146159 2002-05-15
US10/146,159 US6745009B2 (en) 2002-05-15 2002-05-15 Apparatus, and associated method, for facilitating antenna weight selection utilizing deterministic perturbation gradient approximation
US10/334,045 US6842632B2 (en) 2002-12-30 2002-12-30 Apparatus, and associated method, for facilitating antenna weight selection utilizing deterministic perturbation gradient approximation
US334045 2002-12-30
PCT/US2003/015228 WO2003098823A1 (fr) 2002-05-15 2003-05-15 Appareil et procede associe permettant de faciliter la selection du poids d'une antenne a l'aide d'une approximation de gradient de perturbation deterministe

Publications (2)

Publication Number Publication Date
EP1504535A1 true EP1504535A1 (fr) 2005-02-09
EP1504535A4 EP1504535A4 (fr) 2010-04-21

Family

ID=29552717

Family Applications (1)

Application Number Title Priority Date Filing Date
EP03728913A Withdrawn EP1504535A4 (fr) 2002-05-15 2003-05-15 Appareil et procede associe permettant de faciliter la selection du poids d'une antenne a l'aide d'une approximation de gradient de perturbation deterministe

Country Status (5)

Country Link
EP (1) EP1504535A4 (fr)
KR (1) KR100890793B1 (fr)
CN (1) CN100435489C (fr)
AU (1) AU2003234571A1 (fr)
WO (1) WO2003098823A1 (fr)

Families Citing this family (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7236540B2 (en) 2003-06-10 2007-06-26 Telefonaktiebolaget Lm Ericsson (Publ) Channel estimation in a transmission diversity system
US7319868B2 (en) * 2004-09-27 2008-01-15 Telefonktiebolaget Lm Ericsson (Publ) Derivation of optimal antenna weights during soft handover
JP4802193B2 (ja) * 2004-09-27 2011-10-26 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） ソフトハンドオーバー中の最適アンテナ重みの導出
US8254482B2 (en) * 2008-05-13 2012-08-28 Samsung Electronics Co., Ltd. Perturbed decoder, perturbed decoding method and apparatus in communication system using the same
US9997830B2 (en) 2012-05-13 2018-06-12 Amir Keyvan Khandani Antenna system and method for full duplex wireless transmission with channel phase-based encryption
US9008208B2 (en) 2012-05-13 2015-04-14 Amir Keyvan Khandani Wireless transmission with channel state perturbation
US10177896B2 (en) 2013-05-13 2019-01-08 Amir Keyvan Khandani Methods for training of full-duplex wireless systems
US9531483B2 (en) * 2013-06-19 2016-12-27 Qualcomm Incorporated Devices and methods for facilitating signal-to-interference ratio estimates for closed-loop transmission diversity communications
US9236996B2 (en) 2013-11-30 2016-01-12 Amir Keyvan Khandani Wireless full-duplex system and method using sideband test signals
US9413516B2 (en) 2013-11-30 2016-08-09 Amir Keyvan Khandani Wireless full-duplex system and method with self-interference sampling
US9820311B2 (en) 2014-01-30 2017-11-14 Amir Keyvan Khandani Adapter and associated method for full-duplex wireless communication
WO2017173461A1 (fr) * 2016-04-01 2017-10-05 Cohere Technologies, Inc. Précodage de tomlinson-harashima dans un système de communication otfs
US10333593B2 (en) 2016-05-02 2019-06-25 Amir Keyvan Khandani Systems and methods of antenna design for full-duplex line of sight transmission
US10700766B2 (en) 2017-04-19 2020-06-30 Amir Keyvan Khandani Noise cancelling amplify-and-forward (in-band) relay with self-interference cancellation
US11212089B2 (en) 2017-10-04 2021-12-28 Amir Keyvan Khandani Methods for secure data storage
US11012144B2 (en) 2018-01-16 2021-05-18 Amir Keyvan Khandani System and methods for in-band relaying

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6952455B1 (en) * 2000-08-02 2005-10-04 Via Telecom, Co., Ltd. Adaptive antenna method and apparatus

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5515378A (en) 1991-12-12 1996-05-07 Arraycomm, Inc. Spatial division multiple access wireless communication systems
IL120574A (en) * 1996-05-17 2002-09-12 Motorala Ltd Methods and devices for transmitter track weights
US6492942B1 (en) * 1999-11-09 2002-12-10 Com Dev International, Inc. Content-based adaptive parasitic array antenna system

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6952455B1 (en) * 2000-08-02 2005-10-04 Via Telecom, Co., Ltd. Adaptive antenna method and apparatus

Non-Patent Citations (5)

* Cited by examiner, † Cited by third party
Title
3GPP2-DRAFTS, 2500 WILSON BOULEVARD, SUITE 300, ARLINGTON, VIRGINIA 22201 USA, 12 February 2001 (2001-02-12), XP040351356 *
3GPP2-DRAFTS, 2500 WILSON BOULEVARD, SUITE 300, ARLINGTON, VIRGINIA 22201 USA, 20 August 2001 (2001-08-20), XP040263545 *
BANISTER B C ET AL: "Implementation of transmit antenna weight adaptation through stochastic gradient feedback" CONFERENCE RECORD OF THE 35TH. ASILOMAR CONFERENCE ON SIGNALS, SYSTEMS, & COMPUTERS. PACIFIC GROOVE, CA, NOV. 4 - 7, 2001; [ASILOMAR CONFERENCE ON SIGNALS, SYSTEMS AND COMPUTERS], NEW YORK, NY : IEEE, US, vol. 2, 4 November 2001 (2001-11-04), pages 1517-1524, XP010582290 ISBN: 978-0-7803-7147-7 *
RAGHOTHAMAN B ED - INSTITUTE OF ELECTRICAL AND ELECTRONICS ENGINEERS: "Deterministic perturbation gradient approximation for transmission subspace tracking in FDD-CDMA" ICC 2003. 2003 IEEE INTERNATIONAL CONFERENCE ON COMMUNICATIONS. ANCHORAGE, AK, MAY 11 - 15, 2003; [IEEE INTERNATIONAL CONFERENCE ON COMMUNICATIONS], NEW YORK, NY : IEEE, US, vol. 4, 11 May 2003 (2003-05-11), pages 2450-2454, XP010642887 ISBN: 978-0-7803-7802-5 *
See also references of WO03098823A1 *

Also Published As

Publication number Publication date
WO2003098823A1 (fr) 2003-11-27
CN1653706A (zh) 2005-08-10
EP1504535A4 (fr) 2010-04-21
KR100890793B1 (ko) 2009-03-31
AU2003234571A1 (en) 2003-12-02
KR20040108803A (ko) 2004-12-24
CN100435489C (zh) 2008-11-19

Similar Documents

Publication Publication Date Title
US6745009B2 (en) Apparatus, and associated method, for facilitating antenna weight selection utilizing deterministic perturbation gradient approximation
US6842632B2 (en) Apparatus, and associated method, for facilitating antenna weight selection utilizing deterministic perturbation gradient approximation
US7099630B2 (en) Beam forming method
US7096041B2 (en) Beam forming method
US7564914B2 (en) Method and system for frame formats for MIMO channel measurement exchange
US20040018818A1 (en) Method for controlling the weighting of a data signal in the at least two antenna elements of a radio connection unit, radio connection unit, module and communications system
US6987819B2 (en) Method and device for multiple input/multiple output transmit and receive weights for equal-rate data streams
US7656842B2 (en) Method and apparatus for MIMO transmission optimized for successive cancellation receivers
US7917100B2 (en) Method and system for a double search user group selection scheme with range in TDD multiuser MIMO downlink transmission
US9282450B2 (en) Method and system for a greedy user group selection with range reduction in TDD multiuser MIMO downlink transmission
EP1423926A1 (fr) Procede de signalisation en boucle fermee destine a commander des faisceaux d'emission multiples, et dispositif emetteur-recepteur adapte de fa on correspondante
EP1504535A1 (fr) Appareil et procede associe permettant de faciliter la selection du poids d'une antenne a l'aide d'une approximation de gradient de perturbation deterministe
US20070191067A1 (en) Adaptive beamforming systems and methods for communication systems
KR101470501B1 (ko) 양자화된 채널 상태 정보에 기반하여 데이터를 전송하는 장치 및 방법
WO2002041524A1 (fr) Procede de regulation de la ponderation des signaux de donnees dans des emetteurs-recepteurs a elements multiples, et dispositifs et reseau de communication correspondants
US20030152159A1 (en) Communication method, communication system, transmitter, and receiver
JP4170789B2 (ja) 無線通信システム、受信局及び無線通信制御方法
KR20140088185A (ko) 프레임들을 전송하는 방법, 그에 대응하는 스테이션들 및 컴퓨터 프로그램
Zhang et al. Joint antenna and user selection algorithm for uplink of multiuser mimo systems using sequential monte carlo optimization
Novakovic et al. Generalised full/partial closed loop transmit diversity
KR101042170B1 (ko) 폐 루프 방식의 다중 안테나 시스템에서 코드 북 인덱스 탐색방법 및 이를 지원하는 수신장치
Kim Performance enhancement scheme for adaptive antenna arrays in DS/CDMA systems

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

17P Request for examination filed

Effective date: 20041028

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HU IE IT LI LU MC NL PT RO SE SI SK TR

AX Request for extension of the european patent

Extension state: AL LT LV MK

DAX Request for extension of the european patent (deleted)
A4 Supplementary search report drawn up and despatched

Effective date: 20100319

17Q First examination report despatched

Effective date: 20100614

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN

18D Application deemed to be withdrawn

Effective date: 20101026