KR101009329B1 - Repetitive paging from wireless data base station having a smart antenna system - Google Patents

Abstract

Disclosed are a method, apparatus and machine readable medium for transmitting a downlink in a substantially omni-directional manner from a communication station to a first remote communication device on a downlink channel. The communication station has a smart antenna system having a plurality of antenna elements. The method includes determining a first downlink smart antenna processing strategy for transmitting in a first omni directional manner, using the first downlink smart antenna processing strategy, sending a first downlink message from the communication station to the first. Transmitting in an omni-directional manner, and repeatedly transmitting the first downlink message from the communication station in a second omni-directional manner. Repetitive transmissions are non-identical repetition to encourage different interference environments upon repetition.

Directional, Omni-Directional, Omni-Directional, Wireless, Base Station, Communications Station, Terminal, Interference Mitigation, Cochannel

Description

Repetitive Paging of Wireless Data Base Station with Smart Antenna System {REPETITIVE PAGING FROM WIRELESS DATA BASE STATION HAVING A SMART ANTENNA SYSTEM}

Related patent application

The present invention is related to the following three concurrent US patent applications, each of which is assigned to the assignee of the present invention and incorporated herein by reference.

(1) The inventor is Youssefmir et al., The name of the invention is "DOWNLINK TRANSMISSION IN A WIRELESS DATA COMMUNICATION SYSTEM HAVING A BASE STATION WITH A SMART ANTENNASYSTEM," and the agent reference number is 0,5685. P031.

(2) The inventor is Trott et al., And the name of the invention is "COOPERATIVE POLLING IN A WIRELESS DATA COMMUNICATION SYSTEM HAVING SMART ANTENNA PROCESSING", and the agent reference number 016585.P034.

(3) The inventor is Barratt et al., And the name of the invention is "NON-DIRECTIONAL TRANSMITTING FROM A WIRELESS DATA BASE STATION HAVING A SMART ANTENNA SYSTEM", and the agent reference number is 015685. Filed P027.

TECHNICAL FIELD The present invention relates to wireless communications, and more particularly to a method of wireless communication between a base station transmitter / receiver (transceiver) and a plurality of remote user terminals in a cellular wireless communication system or similar wireless communication system. It relates to wireless communication in the environment.

In such a communication system, it is desirable to use a directional antenna system such as a smart antenna system to increase the signal-to-noise ratio of the communication link and reduce the interference. The use of smart antenna systems can also provide resistance to multipath and fading.

The smart antenna system includes an array of antenna elements for increasing the signal-to-noise ratio and / or reducing the interference, and has a mechanism for determining the processing strategy of the smart antenna. The smart antenna system can be a "swiched beam" system that includes a beamformer that forms several fixed beams and that has a mechanism for combining one or more beams. Alternatively, the smart antenna system can be an adaptive antenna array system that includes a smart antenna processing strategy, which can infinitely change the antenna radiation pattern that can be adapted to the processing strategy for a particular reception or transmission situation.

The smart antenna system can be used for uplink (user terminal to base station) or downlink (base station to user terminal) or for both uplink and downlink communications.

Smart antenna systems may also allow for spatial division multiple access ("SDMA"). By using SDMA, as long as co-channel user terminals are spatially separated, one or more user terminals of the base station may have the same "conventional" channel, i.e., the same frequency channel and time channel (FDMA system and TDMA). Communication with a base station in the case of a system) or a code channel (in a CDMA system). In this case, the smart antenna system provides more than one "spatial channel" within the same general channel.

The transmit RF and interference environment can change quite easily in cellular systems. In a packetized system, these environments can vary significantly between sequential packet transmissions. For example, consider a cellular system comprising a smart antenna system and a base station having one or more remote user terminals. In a rapidly changing environment, the determination of an appropriate smart antenna processing strategy requires adaptation to the uplink signal received from the mobile device user during a time interval that strictly corresponds to the transmission period. Such adaptation typically uses a radio signal from the user terminal to the base station with a smart antenna processing strategy determined using such a received signal.

There is a need for techniques that adapt to rapidly changing RF and interference environments.

Polling Polling )

Consider a cellular system comprising several base stations, each with a set of one or more user terminals. Methods of determining a smart antenna processing strategy for a smart antenna system of a specific base station for mitigating interference of co-channel user terminals that may be transmitting signals on the same channel but transmitting signals to other base stations are known in the art. It is. Such interference mitigation can be realized by receiving a radio signal from co-channel user terminals interfering at a particular base station and distinguishing the desired signal from the interfering signal.

Certain base stations may not mitigate interference from other base station user terminals on the uplink or may not mitigate interference towards other base station user terminals on the downlink. A particular base station may not have an appropriate radio frequency link to another user terminal or may have no information on how to poll a user terminal of another base station.

Start communication

When initiating communication with a remote user terminal, the remote user terminal is either logged off to the system, or is not communicating, has communicated between the base station and the user terminal relatively recently, or is near silent. It may be in an "idle" state, communicating at a fairly slow rate over a period of time.

Initiating communication between a base station and a user terminal that may be in an idle state can be relatively difficult. The location of the user terminal may not be known, for example because it is a mobile terminal. In addition, the interference pattern may change rapidly, so even if the location is known, there may be significant interference that may reduce the likelihood of successfully receiving an initiation (eg, paging) message by the base station. In addition, a channel for paging may be used by a user terminal of another base station. In such a case, interference to the desired / intended user terminal can be significant.

The transmission of a paging message for paging (radio calling) a user terminal is typically performed by a user terminal whose location is unknown and likely to change in an environment where interference is rapidly changing, from a base station associated with it. This is done in a consistent way that increases the likelihood of successfully receiving (and other control signals).

A method, apparatus and machine-readable medium for transmitting a downlink in a substantially omni-directional manner in a downlink channel at a communication station to a first remote communication device. The communication station has a smart antenna system having a plurality of antenna elements. In one embodiment, the method further comprises: determining a first downlink smart antenna processing strategy for transmitting in a first omnidirectional manner, using the first downlink smart antenna processing strategy, the first downlink message to the first downlink message; Transmitting from the communication station in the first omnidirectional manner and repeatedly transmitting the first downlink message from the communication station in a second omnidirectional manner. Repetitive transmissions are non-identical repetition to encourage different interference environments upon repetition.

One embodiment includes a method of paging a first remote communication device on a downlink from a first communication station of a communication system. The communication system does not include or includes one or more other communication stations separate from the first communication station, each of which is associated with one or more other remote communication devices. The first communication station is associated with at least the first remote communication device and includes a smart antenna system having an array of antenna elements. The method includes providing a first set of sequential time intervals to a first communication station to communicate with its associated remote communication device, each of the first set of time intervals being a selected number of downlinks. Includes regular channels. The method also includes transmitting a first paging signal from the first communication station to the first remote communication device during a first downlink normal channel of the first set of first time periods, and after the first time period. And repeatedly transmitting, wherein the repetitive transmission is to transmit a second paging signal from the first communication station to the first remote communication device on the first set of downlink regular channels. The repeating transmitting step includes a set of remote communication devices actively receiving on the downlink to the first downlink general channel during the first (first) transmitting step for paging during the repeatedly transmitting step. Use a strategy that is not the same iteration to be different from the set of telecommunications actively receiving on the downlink general channel used.

1 illustrates a communication system including at least two base stations and at least one base station having a smart antenna system.

2A and 2B show two embodiments of a base station using a smart antenna system, FIG. 2A shows one configuration in which the smart antenna system is an adaptive antenna array system, and FIG. 2B includes a beamforming network. FIG. 4 shows another base station having a switched beam smart antenna system.

3 illustrates a signal timing arrangement according to an embodiment of a half duplex of the present invention.

4 illustrates a signal timing arrangement according to an embodiment of the full duplex of the present invention.

5 is a diagram illustrating a signal timing arrangement according to another embodiment of the present invention.

Cellular Systems and Their Smart Antenna Base Stations

Referring to FIG. 1, a cellular wireless communication system 100 having at least two base stations, namely a first base station 102 and at least one second base station 111, is shown generally, and a first base station 102 is shown. Includes a smart antenna system having an array of antenna elements 104. The cellular wireless communication system 100 also includes a plurality of remote, possibly mobile user terminals 105, 106, 107, 108, and a second base station that perform bi-directional packet communication with the first base station 102. And a plurality of remote, possibly mobile user terminals 109, 110 that perform bidirectional packet communication with other base stations, such as 111. The first base station 102 is associated with the mobile user terminals 105, 106, 107, 108 and the second base station 111 is associated with the mobile user terminals 109, 110.

The first base station 102 is connected to a network, such as a data and voice network. One or more second base stations 111 may also be connected to the same network as the network. In one embodiment, the first base station 102 and the other base station 111 are connected to the Internet.

2A illustrates one embodiment of a first base station 102. The base station includes a smart antenna system 203 that is an adaptive antenna array system. The smart antenna system 203 has one transmitter and one receiver for an array 104 of antenna elements, each of the individual antenna elements of the array 104, in one embodiment a transmitter / receiver (“transceiver”) ( A set of transmitters and a set of receivers implemented as a set of 206, and a spatial processor 208 that performs uplink and downlink smart antenna processing.

Uplink smart antenna processing includes a combination of signals received from individual antenna elements via a set of transceivers, and downlink smart antenna processing includes multiple versions of signals transmitted by individual antenna elements through a set of transceivers. Includes generation. The control computer 210 controls the smart antenna processing. Spatial processor 208 and control computer 210 include one or more digital signal processing (DSP) devices, and any other mechanism for realizing uplink and downlink smart antenna processing and control. You can also use

On the uplink, smart antenna processing weights the received signal in amplitude and phase according to a set of uplink weighting parameters to conveniently combine the received signal under the control of the control computer 210. weighting). This combination is called uplink spatial processing and uplink smart antenna processing. The uplink smart antenna processing strategy is in this case defined by a set of uplink weighting parameters. Such combining may further comprise temporal filtering for time equalization, and when combined with spatial processing such combining may be uplink spatial-temporal processing, or uplink smart antenna processing. It is called.

Space-time processing is performed according to an uplink smart antenna processing strategy defined by a set of uplink weighting parameters that include time processing parameters for signals originating at each antenna element. For simplicity, uplink spatial processing and uplink smart antenna processing will mean here either uplink space-time processing or uplink space processing.

The uplink strategy is generally determined based on the signal received at the antenna element of the first base station 102, and in one embodiment the downlink strategy is also determined based on the signal received at the antenna element.

Thus, in one embodiment, the first base station 102 is a downlink transmission unit coupled to the antenna element to transmit downlink data in the downlink channel to the associated remote user terminal, the antenna to receive uplink signals from the remote user terminal. An uplink receiving unit connected to the device, and connected to the downlink transmitting unit and the uplink receiving unit, determine a downlink smart antenna processing strategy based on an uplink response signal.

In one embodiment, the antenna elements 104 of the first base station 102 are each used for both transmission and reception, and in other embodiments, the plurality of antenna elements includes separate antennas for transmission and reception.

User terminals, such as 105, 106, 107, 108 generally include an antenna system and a transceiver, and input devices to provide various types of functionality, such as voice and / or data communications, via the Internet or other data communications networks. And / or to an output device and / or a processing device. In one embodiment, the antenna system may include one antenna, and in another embodiment, the antenna system may include a plurality of antenna elements to facilitate diversity reception and transmission. In yet another embodiment, the antenna system comprises a smart antenna system. The user terminal may be capable of voice and / or data communication between user terminals in one embodiment.

A computer, such as a laptop computer, a two-way pager, a personal digital assistant (PDA), a video monitor, an audio player, a cellular phone, or other communication device connected to or as part of the user terminal. Or one or more other devices capable of transmitting voice or data wirelessly with a communication station, such as a base station.

When a signal is received from one of the remote user terminals 105, 106, 107, 108, the adaptive spatial processor 208 is responsive to the amplitude and phase of the signal as received at each of the antenna elements of the array 104. Perform uplink spatial processing combining the signals in a manner that effectively provides a directional receive pattern that advantageously enhances the signal link from the user terminal to the base station, including compensation in the possible multipath conditions and providing interference mitigation. .

Various techniques are known for determining an uplink smart antenna processing strategy as defined by weighting parameters. In one embodiment, a training sequence of symbols of known symbols is included in the uplink signal. One variation of the embodiment uses the least squares method for strategy determination. In another embodiment, the " blind " method according to a reference configured to have one or more characteristics, for example, known to have a constant modulus or a particular modulation format. This is used. An error signal is formed using a known signal or a configured reference signal, and the uplink smart antenna strategy determination determines an uplink weighting parameter that optimizes certain criteria based on the error. In one embodiment, the criterion is a least squared error criterion.

One embodiment may operate according to a spatial division multiple access (“SDMA”) system. By using an SDMA system, one or more user terminals associated with the first base station 102 may be connected to the same "conventional" channel, i.e., the same frequency and time channel, as long as remote users of the same channel are spatially separated. It can communicate with the first base station 102 on the uplink (in the case of FDMA and TDMA systems) or in the code channel (in the case of a CDMA system). In this case, the smart antenna system provides one or more "spatial channels" within the same common channel, and the adaptive spatial processor 208 performs uplink spatial processing to share a common channel with the desired user terminal (a base station). Mitigate interference from the remote terminal associated with 102).

The first base station 102 may also be in a manner that effectively provides a directional signal pattern that advantageously enhances the signal link from the base station to the user terminal, including mitigation of interference and mitigation of multipath conditions that may exist. It is used to send signals to one or more remote units 105, 106, 107, 108. SDMA also allows base stations in the downlink direction to transmit to one or more associated user terminals on the same common channel. That is, the same general channel may have more than one spatial channel.

In the downlink, the spatial processor 208, under the control of the control computer 210, weights the signal in amplitude and phase according to a set of downlink weighting parameters, thereby varying the version (version, version). Such processing is generally referred to as downlink spatial processing or downlink smart antenna processing. In this case, the downlink smart antenna processing strategy is determined by the downlink weighting parameter. Such processing may also include visual filtering for time equalization, and when combined with weighting, such smart antenna processing is referred to as downlink spatio-temporal processing. Downlink space-time processing is performed according to a downlink smart antenna processing strategy defined by a set of downlink weighting parameters that include time processing parameters for the signal to be transmitted by each antenna element. For simplicity, downlink spatial processing and downlink smart antenna processing will mean downlink space-time processing or downlink spatial processing here.

Various mechanisms are known for determining the downlink smart antenna processing strategy determined in this case by the downlink weighting parameters. One embodiment operates in a communication system 100 that is a TDMA system using Time Domain Duplexing (TDD) such that the uplink frequency and downlink frequency between a particular user terminal and the associated base station are the same. The downlink weighting parameters are generally determined from uplink weighting parameters for the same user terminal. The calibration factor is the difference in distortion, e.g., the amplitude shift and phase shift that occurs when a signal passes through different receive and transmit chains connected to each of the antenna tenants of the array 104. To compensate for the difference, it is included when determining the downlink weighting parameter from the uplink weighting parameter. Such chains include antenna elements, cables, filters, RF receivers, RF transmitters, physical connections, and analog-to-digital (AD) converters when the processing is digital. US patent applications 08 / 948,772 and 09 / 295,434, assigned to the applicant of the present invention, respectively, include a description of a calibration apparatus and method, for example.

In another embodiment operating in a communication system that does not use time domain duplexing, for example, frequency domain duplexing (FDD) in which the uplink frequency and the downlink frequency for communicating with a particular user terminal are not the same. In one embodiment of the present invention operating in a system that uses a number of techniques available for determining the downlink weighting parameter from the uplink signal received from the user terminal is varied, the direction of arrival of the user terminal (DOA) Determining but not limited to.

2B illustrates another embodiment of a first base station 102 that includes a smart antenna system 223 that is a switched beam system. The smart antenna system 223 includes an array 104 of antenna elements, a beamforming network 225 that forms a set of fixed beams for the antenna elements of the array 104, and individual beam terminals of the beamforming network 225. a set of transceivers 227 having one transmitter / receiver for each beam terminal, and a combiner 229 that combines one or more beams of the transceiver 227. The included control computer 231 controls the smart antenna system. Exemplary beam formers include, but are not limited to, a Butler matrix. The combiner 229 selects one or more fixed beams for use in the uplink or downlink, and can include a switching network for selecting one or more beams. Coupler 229 may also include a mechanism to combine one or more beams. With the adaptive smart antenna system of FIG. 2A, the determination of how to control the switched beam smart antenna system for downlink communication is referred to as the determination of the downlink smart antenna processing strategy.

The processing of combiner 229 during downlink communication is referred to as downlink spatial processing. In the uplink, combining works by weighting the selected beams according to a set of uplink weighting parameters to advantageously combine the received signals. When equipped with the adaptive smart antenna system of FIG. 2A, such uplink combining is referred to as uplink spatial processing, and determining the combining for uplink communication is referred to as determining the uplink smart antenna processing strategy.

More specifically, when a signal is received from one of the remote transmitters of the remote units 105, 106, 107, 108, the combiner 229 beamforms in response to the signal received at each of the antenna elements of the array 104. Uplink spatial processing combining beams from the network 225 enhances the signal link from the user terminal to the base station, including compensation for possible multipath conditions and mitigation of interference in accordance with an aspect of the present invention. In a manner that effectively provides a directional signal pattern.

2B, in the downlink, the combiner processes the signal to determine the weighted version to transmit on the selected one or more beams of the beamforming network 225. The processing of the combiner is to improve transmission from the base station to the user terminal, including compensation for possible multipath conditions and mitigation of interference in accordance with one aspect of the present invention.

In both the embodiments of FIGS. 2A and 2B, according to one aspect of the present invention, signals are also received from co-channel users, such as remote units 109, 110 of other base station (s) 111. Spatial processing uses these received signals in a manner that mitigates interference from co-channel users, such as remote units 109 and 110 of other base stations 111.

Adaptive determining of the preferred smart antenna strategy is particularly effective in RF and interference environments, such as in cellular systems, in the case of cellular communication, or in the communication of data in a computer network such as the Internet, or a combination of such factors. Due to the change, it works best at certain times of data communication. When the remote user terminal is moving, the movement of the user terminal can result in the movement of the user terminal between the preferred place and the undesirable place between subsequent data transmissions. In the case of data transmission, for example, when the communication system 100 is part of a computer network such as the Internet, the data transmitted between the user terminal and the first base station 102 may change rapidly in the interference environment. Thus, in the case of the first base station 102, an interferer such as the remote terminals 109, 110 may be transmitted to their respective second base stations 111 at different times, and the interference pattern changes drastically. can do.

Start communication from the base station

When initiating communication from the first base station 102 on the downlink, in order to quickly determine an optimal smart antenna processing strategy, according to an embodiment of the present invention, the first base station 102 is agreed- upon a logical control channel transmits an initial downlink paging message to the user terminal indicating that the first base station 102 wishes to initiate communication.

The user terminal may not be logged in, or may be idle when logged in and authenticated, but may not be active to communicate with the associated base station, or may be active to actively communicate with the associated base station. When the user terminal is in an idle state, both the base station and the user terminal are ready to initiate communication. In addition, both the base station and its idle terminal have information indicating a channel of the base station for paging the user terminal or a channel or potential channel set of the user terminal for initiating communication with the base station.

Note that the user terminal has the ability to communicate on more than one channel, so that one channel may be idle and the other channel may be active. Note that an idle user terminal may not be idle for other channels.

The transmission of a paging message for paging the user terminal is unknown in an environment where the interference varies considerably, and the user terminal, which changes position, may successfully receive such paging (and / or other control signals) from the associated base station. It is desirable to run in some way that increases the likelihood of receiving.

One aspect of the invention is that in transmitting a downlink signal in a non-directional manner, each of the one or more user terminals may receive one or more signals on a particular downlink channel during transmission of the downlink signal. It simultaneously mitigates interference towards one or more user terminals known to the base station as unwanted terminals.

The omnidirectional approach refers to not intentionally directing energy towards any particular user or users, as used herein. In a sectorized system, this means omni-directional within the sector. Substantially omnidirectional also means omnidirectional with respect to the time average, where the entire transmission is broken down into a set of repeated transmissions, each with perhaps a different strategy.

One aspect of the present invention involves a method of reliably initiating communication from a base station, such as first base station 102, to a particular user terminal in a wireless packet data system, such as system 100. This method is particularly useful for base stations with smart antenna systems as described below.

One embodiment of the method includes relatively high encoded, relatively low rate paging message transmission by the first base station 102 to obtain a responding user terminal. Encoding is one of the methods that facilitates the detection of relatively high probabilities at the user terminal. Since much information is not transmitted, it transmits a low speed signal. The user terminal detects and responds to the paging message. The response is then used by the base station to obtain information about the communication link of subsequent transmissions. This information about the communication link is generally reliable and provides relatively high speed (eg, traffic data) communication between the base station and the user terminal. User terminals of other base stations may respond to their respective base stations on the same general channel, which response may also interfere with or from co-channel user terminal (s) interfering in subsequent downlink or uplink transmissions. Can be used to mitigate.

Multiple users Between terminals Downlink  Sharing data transmission Downlink  On the channel Paging

In one embodiment, the paging message may be sent in a logical control channel that may occupy the same common channel as other data, such as traffic data communicated between the first base station 102 and one or more user terminals.

The paging message is also a logical control channel that can occupy the same common channel as other data, such as traffic data or paging data communicated between other base stations and one or more user terminals, to be transmitted from the first base station 102. Can be.

Further, the paging message may be transmitted from the first base station 102 in a logical control channel that may occupy the same common channel as other user terminals associated with the first base station 102 and other users of one or more other base stations.

One embodiment includes providing a unique paging sequence called UT-Sequence for each user terminal. This sequence can be generated in several ways. For example, the base station identification number and the user terminal identification number can be used as input to the PN sequence generator. The resulting bit is then modulated and the resulting I / Q baseband sequence constitutes a UT_Sequence. There are many other ways to create a UT_Sequence. For example, the user terminal identification number can be encoded using a low-rate error correction code, the coded number being XOR operation with the output of the PN sequence generator beginning with all or part of the base station identification number. Scrambled to UT_Sequence is such that the probability that two user terminals have the same paging sequence is relatively low, and in one embodiment, UT_Sequence is unique for each user terminal of the system. In one embodiment, the UT_Sequence includes coding that provides a very high degree of redundancy to increase the likelihood of successfully receiving the UT_Sequence at the desired user terminal.

Each user terminal listens for an attempt to detect its UT_Sequence on the negotiated logical control channel. This logical control channel may be a control channel or, in accordance with one aspect of the present invention, a generic channel that is also used for traffic by other user terminals in the system.

The user terminal uses the user terminal sequence detection technique until it successfully detects its UT_Sequence. One detection method uses correlation, along with detection criteria that include a correlation threshold.

The first base station 102 has information indicating which channel or channels the desired user terminal is listening to, in some agreed upon manner, and the base station transmits a UT_Sequence for this channel. The listening channel or channels may be, for example, by agreement during the initial exchange or during the registration ("login") of the user terminal and its associated base station. The first base station 102 has determined a smart antenna processing strategy for the smart antenna system to increase the probability of successful reception of the UT_Sequence by reducing the likelihood that interference will interfere with the communication.

Prior to paging, the first base station 102 may determine that signals from one or more of the associated user terminals (" prior-to-paging received signals, " Although it is known to receive the paging preceding received signal ") and thus not transmitting, any user terminal or terminals associated with the first base station 102 are simultaneously paging from the first base station 102 to the same general channel. During any time it is possible to receive data that is a message, it transmits on the uplink to the first base station 102.

The first base station 102 uses the paging preceding received signal to simultaneously transmit paging messages on different spatial channels of the same general channel with data to such co-channel user terminals at the same time. Determine your strategy.

In addition to receiving signals from an associated user terminal, the first base station 102 can receive signals from the interferer. The first base station 102 distinguishes a signal from its associated user terminal with a signal from an interferer. In one embodiment, this distinction uses a user terminal identifier.

It should also be noted that there may be no other user terminal associated with the first base station 102 that may share the paging message and the downlink general channel.

The communication system may also include one or more other base stations, and in one embodiment, these other base station (s) have the same functionality as the first base station 102. Thus, in addition to receiving the paging preceding received signal, the first base station 102 may also receive a signal from one or more other user terminals associated with the other base station (s) ("other user terminal received signal, other") before paging the user terminal to be paged. -user-terminal received signal "). Such other user terminals include terminals capable of transmitting signals on the same general channel as the paging message.

The first base station 102 distinguishes a signal from a user terminal associated with it and a signal from another user terminal (s) associated with another base station (s). Other user terminal (s) associated with the other base station (s) may receive data from their respective associated base station (s) simultaneously and with the same general channel, such as paging from the first base station 102. Care must be taken.

Each base station uses a protocol for communicating with a user terminal associated with it, such that the base stations use equivalent protocols, including the equivalent protocols used by the base stations.

The first base station 102, using the paging preceding received signal and the other user terminal received signal, simultaneously transmits data to its associated cochannel user terminal and transmits the paging message on a different spatial channel at the same time. 1 employs a downlink smart antenna processing strategy for its smart antenna system to mitigate interference to the user terminal associated with the base station 102 and to other user terminal (s) from which other user terminal received signals have been received. Decide

According to one embodiment of the invention, the determination of the downlink smart antenna processing strategy uses a downlink weighting parameter determined from the uplink weighting parameter using calibration. The uplink weighting parameter is determined from the signal received at the antenna element of the antenna array corresponding to the user terminal received signal different from the paging preceding received signal.

In one embodiment, the determination of the smart antenna processing strategy uses calibration using a received covariance matrix of signals received at an antenna element of the antenna array corresponding to a user terminal received signal that is different from the paging preceding received signal. Use the determined transmit covariance matrix. In particular, the strategy includes mitigating interference using an interference covariance matrix for signals arriving from interfering remote users.

If Z _R is the general channel to be used for paging and for all signals received from the associated user terminal to the base station, then m n n matrix of the signals received at the antenna element, then each row is at one of the m antennas. It is a vector of n complex (I and Q) samples of the received signal. Assume that m × 1 vector of complex random variables (I and Q values) representing the signal and noise received at each of the m antennas. The receive covariance matrix is defined as R _R = E [z _R z _R ^H ] where E [.] Is an expectation operation and superscript H is a complex conjugate transpose operation, or Hermit. Hermitian transpose, for m antenna elements, the reception covariance matrix R _R is an m × m matrix. If there is only interference on the channel as it may occur when no desirable uplink signal is present, i.e. when in a desired user terminal idle state, the receive covariance matrix is defined as R _RI = E [Z _RI Z _RI ^H ]. A reception interference covariance matrix, where Z _RI is a vector of complex (I and Q value) probability variables of a signal arriving at one of the m antenna elements of the antenna unlay from a remote terminal that transmits interference.

The received interference covariance matrix contains information about the average spatial behavior of the interfering remote terminals. The eigenvector of this matrix defines the average spatial direction used by the interference. The eigenvalues of the received interference covariance matrix represent the average power used by the interference in each eigenvalue direction. Thus, the eigenvector direction associated with a relatively large eigenvalue represents the spatial direction of receiving a relatively large average interference power, and the direction of the eigenvector associated with a relatively small eigenvalue represents the spatial direction of receiving a relatively small average interference power.

In one embodiment, the expectation calculation is performed by averaging samples of the signals. That is, R _R = Z _R Z _R ^H and R _Ri = Z _pi Z _Ri ^H , where Z _Ri is m × of received signal samples at the antenna element for a signal received at a base station without any desired uplink signal. n matrix, and each row is a vector of n complex (I and Q value) samples of the signal received at one of the m antennas.

In one embodiment, the receive covariance matrix is used to determine the desired downlink processing strategy and includes interference mitigation towards unwanted cochannel user terminals. During the calculation of the receive covariance matrix, the case where a portion of the set of cochannel user terminals transmits is also received when the first base station transmits and this strategy is quite effective in realizing interference mitigation.

According to one aspect of the present invention, prior to paging, the receive interference covariance matrix is transmitted simultaneously by the unwanted user terminal, which may be receiving on the downlink to the same general channel as the paging message, Sampling is determined during times when the user to be paged is known to be not transmitting (i.e., idle), except while there may be.

Alternatively, the interference covariance matrix may be received later on the downlink in the same general channel and time as the user terminal and other user terminal to be paged at the same time—at the first base station 102, which may be transmitting. It may be determined by performing uplink spatial processing on the received signal. Uplink spatial processing determines the signal from the user terminal to be paged and subtracts the interfering signal.

The reception covariance matrix is a signal received by the first base station 102 at the same time (eg, paging preceding received signal) when the potential cochannel remote terminal is likely to transmit data and when the desired user terminal is idle. And other user terminal received signals). This receive covariance matrix is the same as the receive interference covariance matrix and can be used to advantageously determine a smart antenna processing strategy for signal reception, including interference mitigation from interfering transmitters.

Transmit spatial processing for paging, including interference mitigation towards unwanted user terminals, may therefore be determined from the received interference covariance matrix determined when the unwanted user terminal is transmitting on the uplink, provided that the calibration or other operation This is done because of differences in the chain of electronics to and from the antenna elements. In particular, the set of downlink weighting parameters of the downlink spatial processing for transmitting paging is obtained from the eigenvectors of the received interference covariance matrix, which has a relatively small value but preferably does not necessarily have a minimum value.

Note that, as described further below in accordance with one embodiment of the present invention, traffic communication activation between the base station of the communication system 100 and its associated user terminal occurs in a set of consecutive time intervals (frames), Each frame is divided into a selected number of downlink normal channels (e.g., a time period for a TDMA system). For each of the downlink generic channels, there is an associated acknowledgment generic channel (eg, the time zone of the TDMA system) on the uplink. The following description will generally apply to one embodiment of the invention used in a TDMA system, but the invention is not limited to a TDMA system.

In a TDMA system, each frame is divided into a selected number of downlink data transmission periods (timeslots), and for each downlink data transmission period, the associated acknowledgment transmission period (times) on the uplink. Slot). After communication is established between the first base station 102 and the desired user terminal, the downlink data transmission from the first base station 102 to the user terminal is performed during the initial associated acknowledgment transmission period (downlink data transmission). The most recent acknowledgment transmission period on the uplink associated with the downlink data transmission period for is preferred but not required), proceeded by an acknowledgment signal from the user terminal. The acknowledgment signal received on the uplink is a smart antenna of the first base station 102 for transmission to the desired user terminal in the downlink data transmission period in the future, preferably but not necessarily, related to the acknowledgment transmission period. It is advantageously used to determine the processing strategy of the system. In addition, since the set of sequential time periods used by the base stations are equivalent, other responses from interfering user terminals of the same base station or of other base stations are also received at the first base station 102 to support the smart antenna processing strategy. Used to determine. Thus, the number of user terminals of the communication system 100 that transmit to their respective base stations during the acknowledgment period in the uplink may be transmitted during the associated future—preferably, but not necessarily—downlink data transmission period. Is a superset of the set of desired user terminals in the active state

In one embodiment of sending a paging message to an idle user terminal during a particular downlink data transmission period, the downlink smart antenna processing strategy is determined from a signal received during calibration and a previously associated acknowledgment transmission period in the uplink. It is determined using the eigenvector with the smallest eigenvalue of the covariance matrix.

The use of this paging strategy is such that, during the previous associated acknowledgment transmission period in the uplink, the signal (eg, paging preceding received signal and other user terminal received signal) is transmitted by the first base station 102. Interference mitigation for the user terminal that was received. The eigenvectors of the received covariance matrix corresponding to these signals received from the transmitting user terminal will have eigenvalues significantly greater than the minimum eigenvalue. Thus, in one embodiment, the paging message is sent in a direction that was the least powerful interferer in the uplink to minimize interference towards the cochannel user.

In another embodiment, the eigenvectors of the transmission (interference) covariance matrix having a value less than the provided threshold may be used to determine a downlink smart antenna processing strategy (eg, downlink weighting parameter) for use in paging. have. This eigenvector is substantially in the null space of the transmission interference covariance matrix.

Our definition of omni-directional transmission as mentioned here includes null space transmission that "directs" energy in the direction of the relatively small eigenvector of the covariance matrix.

In another embodiment, the received signal covariance matrix, determined simultaneously when a potential cochannel remote terminal is likely to be transmitting data, and when the desired user terminal is idle, is null in the direction of the unwanted cochannel user. ) Is used in conjunction with the calibration to explicitly convey) and simultaneously transmit the paging message in a different direction according to the omnidirectional radiation pattern. The omnidirectional pattern is a special case of transmitting in an omnidirectional manner.

In a sectored system, omnidirectional means substantial omnidirectional within the sector. In addition, substantially omnidirectional also means substantially omnidirectional relative to the time average when the entire transmission is broken down into a set of repeated transmissions, each of which may possibly have a different strategy.

US patent application Ser. No. 08 / 988,519, filed Dec. 12, 1997 and assigned to the applicant of the present invention, is a method of determining downlink spatial processing weighting parameters for realizing any desired radiation pattern. Provide a description. According to Goldburg's method, the weight is determined by optimizing the optimization criterion. For other embodiments of the present invention, Goldburg's method may be modified to include null transmissions to likely interferers as determined from the covariance matrix.

Alternatively, a method based on Direction-Of-Arrival (DOA) may be used to determine the downlink smart antenna processing strategy.

Another method of mitigating interference towards an undesired user terminal includes configuring side information about the undesired user terminal from a signal received at the first base station 102 from the undesired user terminal at a slightly earlier time. This additional information may be stored in a database of the first base station 102.

The additional information about the unwanted user terminal is information about the user that can be used to determine a strategy that includes mitigating interference towards the unwanted user terminal. One example of such stored additional information about the user terminal is the spatial signature of the user terminal. For example, U.S. Patent Application No. 5,592,490 to Barratt et al., Entitled "SPECTRALLY EFFICIENT HIGH CAPACITY WIRELESS COMMUNICATION SYSTEMS," and OPROCESSING, "SPECTRALLY EFFICIENT HIGH CAPACITY WIRELESS COMMUNICATION SYSTEMS WITH SPATIO-TEMPORAL PROCESSING". US Patent Application No. 5,828,658 provides a description of some techniques for mitigating interference using spatial signatures. Receive space signature describes a characteristic of how a base station array receives signals from a particular user terminal without any interference or other user terminals. The transmit space signature of a particular user terminal describes the characteristics of how the remote user terminal receives the signal from the base station without any interference. The transmit space signature can be determined from the receive space signature using calibration.

The additional information is retrieved from the database and used to determine the smart antenna processing strategy to include mitigating interference to at least one of the unwanted user terminals.

The additional information may be constructed from signals received from unwanted user terminals at the same first base station 102. Alternatively, the communication system may include at least one second base station and an inter-base-station communication mechanism. This inter-base station communication mechanism may be wired and / or wireless. One or more other base stations receive signals from unwanted user terminals, and configuring additional information for each of the unwanted user terminals occurs at other base stations receiving signals from each such unwanted user terminal. This additional information is communicated to the first base station 102 using an inter-base station communication mechanism. If such a method is used, such other base station communicates to the first base station 102 which of the undesired users does not really "really" want.

Other configurations of the side information include DOAs of one or more unwanted user terminals and signals received from actually unwanted user terminals.

Although one embodiment implements a method of operating in a TDD system, the present invention is also applicable to operation in an FDD system. In an FDD system, the transmit channel and receive channel are generally not related to each other at any given moment. DOA based techniques can be used to determine the downlink smart antenna processing strategy from the arrival direction of the user terminal. In addition, the transmit covariance matrix and the receive covariance matrix are generally substantially practical in FFD systems when a time average sufficient to calculate the receive covariance matrix or the interference covariance matrix is used, especially when the uplink frequency is close to the downlink frequency. same. In this case, the use of the downlink space processing strategy determined from the uplink space processing strategy is described, for example, in PCT International Patent Publication No. WO 98/09385 of Clarity Wireless, Inc., published March 5, 1998. : Raleigh et al., Title of the invention: "SPATIO-TEMPORAL PROCESSING FOR COMMUNICATION"] can provide satisfactory results.

The present invention is also applicable to a CDMA system. Often, a CDMA system provides virtually all of the resources of a frequency channel to a small number of user terminals. Thus, the eigenvalues associated with the eigenvectors of the received covariance matrix corresponding to the transmitting user terminal will be significantly greater than the minimum (ie, zero space) eigenvalues.

Thus, one embodiment of the present invention allows a base station to send downlink messages to a desired user terminal in an omni-directional system (e.g., paging of a remote terminal), thereby mitigating interference to other user terminals at the same time. Also, in one embodiment, the first base station 102 simultaneously transmits different data to one or more other user terminals. Thus, one embodiment of the present invention also provides a combination of broadcast traffic (such as paging) and transmitted traffic (such as ongoing traffic data) over the same general channel.

Repeated paging ( Repetitive Pageing )

In response to successfully receiving the paging message, the user terminal transmits a signal to the first base station 102. The user terminal responds by sending a random access request signal to the base station on the negotiated channel. The first base station 102 then sends an access assignment message to the user terminal that includes the designation of a downlink transfer time period and frequency channel for traffic communication. This access assignment message can also be used to perform some control functions and / or to perform strategic control, including measuring path loss between the user terminal and the base station.

The paging message is preferably relatively encoded, but not necessarily. There are many methods for detecting a highly enriched UT_Sequence from a signal received at a receive antenna of such a user terminal. One such technique is to use correlation.

The random access request signal is thus an indication to the first base station 102 indicating that the desired user terminal has successfully detected its UT_Sequence. In one variation, the absence of the random access request signal provides feedback to the first base station 102 that the desired user terminal did not successfully receive paging. Other methods of providing feedback on success or failure can also be used in other embodiments of the present invention.

Thus, in one embodiment, the first base station 102 receives feedback indicating whether the desired user terminal has successfully received paging.

Another aspect of the invention is successful paging by repeating the transmission of the paging one or more times using the same downlink strategy, i.e., the same relative repetition, i.e., the same relative time part of the future frame. This method further increases the probability of detection. Non-identical repetition indicates that one or more downlink strategies or relative time portions of future frames are different. In one embodiment, non-identical iterations are used to encourage different interference environments in the iterations and thus increase the cumulative likelihood that the desired user terminal will successfully receive paging rather than in the case of the same iterations. For example, different timings may be used, or different smart antenna strategies may be used to increase the likelihood of differentiating interference environments. Downlink strategy diversity is used by using different downlink smart antenna strategies, or interference diversity is provided by repeating paging in different interference environments. In one embodiment, both downlink strategy diversity and interference diversity are used.

In one embodiment, feedback is used as to whether the paging was successful. After the first paging fails, the base station repeats paging in future-for example, next-frame using a different omni downlink strategy in one embodiment.

In a first embodiment, the different omni-directional strategy transmits substantially toward the other of the eigenvectors in the zero space of the interference covariance matrix to determine the smart antenna processing strategy for downlink paging. Repetition in future frames of a frame sequence provides paging even if different sets of different interferers are present because, for example, the set of different user terminals may be paged in the next frame because the interference environment may change rapidly. can do. Different eigenvectors in null space can be used to deliver paging through different radiation patterns that provide downlink strategy diversity.

The interfering environment may not change rapidly enough. Thus, in the second embodiment, the repetition is performed in different downlink data transmission periods of a set of sequential time periods. In the case of TDMA, for example, this coincides with a different timeslot. To generalize, repeated transmissions occur on a downlink normal channel that is different from the specific downlink traffic data transmission normal channel of the first transmission. For an FDMA system this may be a different frequency.

Accordingly, according to the second embodiment, the reception interference covariance matrix is determined from a signal received in an acknowledgment transmission period associated with a different downlink data transmission period, and the eigenvectors of the reception interference covariance matrix having the minimum eigenvalues are different interference environments. In order to facilitate repetition of paging at, during this different downlink data transmission period during transmission of the paging, it is used to determine the downlink spatial processing of the smart antenna system.

Another embodiment implements repetitive paging with a downlink strategy that is not necessarily determined from the interference covariance matrix. In another embodiment, paging to a particular user terminal is repeated transmission using a different one of a sequence set of weighted parameters of a smart antenna system designed to increase the probability that a user terminal at an unknown location receives paging. do. For example, US Pat. Appl. No. 09 / 020,619, filed Feb. 9, 1998, assigned to the applicant of the present invention, describes a technique for determining this sequence. The sequence of weighting parameters used in the smart antenna strategy of sequential transmission of messages is, according to the invention, an orthogonal sequence of complex-value weighting parameter sets based on a Discrete Fourier Transform (DFT). To further increase the chance of successful reception of paging, repetition of paging transmissions occurs during different downlink data transmission periods to facilitate repetition of paging in different interference environments.

In another embodiment that uses paging repetition, paging is each transmitted in a wide, e.g., omni-directional beam, while during each different repetition, paging is a different downlink data transmission period (e.g., different timeslots). ) To ensure that repeated paging occurs in different interference environments. A method of transmitting in an omnidirectional pattern is described, for example, in US patent application Ser. No. 08 / 988,519 to Goldburg, supra.

In one embodiment, each downlink data transmission period is divided into two halves for paging. Paging may be sent in the first half or second half of any downlink data transmission period. This provides significantly more paging messages within a certain number of downlink data transfer periods. It also provides another way of changing the interference environment between repetitions of paging. After paging is transmitted in half of the downlink data transmission period, the next iteration is transmitted in the other half of the downlink data transmission period of the next frame, and the downlink transmission period in one embodiment is different. Thus, at least the interference environment for the paging transmission may vary between the first transmission and the second transmission.

Another embodiment includes dividing the downlink data transmission period into two or more paging periods.

3 shows a frame sequence of one embodiment of the present invention used with TDMA. 3 (A) shows three complete frames. 3 (B) shows a single (Nth) frame. 3 (C) shows how long the downlink data transmission period is, in which case the period D3 is divided into first and second halves for paging. Likewise, FIG. 4 shows another full duplex arrangement. 4 (C) shows how long the downlink data transmission period is, and in this example, period D3 is divided into first and second halves for paging.

In one embodiment of the invention, the number of iterations is a function of the estimate of proximity of the desired user terminal to the paging base station. Proximity of the user terminal is estimated during initial registration (eg, login) or prior successful paging sequence. In general, but not necessarily, it is assumed that a user terminal estimated to be close to a paging base station suffers less interference than a user terminal estimated to be far away. In one embodiment, the estimated proximity is one of near, far, and far distant, the near user terminal receives one paging (ie no repetition), and the far user terminal receives two paging (ie , One repetition), a very remote user terminal receives two repetitions.

However, other embodiments may use other criteria to determine various number of repetitions. A method of repeating transmission of paging using a smart antenna system from a base station with a smart antenna system to a user terminal, such that each repetition occurs in a different interference environment, has been disclosed in accordance with at least one embodiment of the present invention.

traffic  Communication( Traffic Communication )

In one embodiment of the invention, traffic communication between a base station and its associated user terminal occurs according to a wireless protocol. The wireless protocol provides a first set of sequential time intervals (frames) such that the first base station 102 communicates with its associated user terminal. The wireless protocol also provides a further set of successive time intervals (frames) for each set of other base stations 11 of the wireless communication system.

3 is a diagram showing a set of transmission times for explaining a transmission sequence in the case of one embodiment of a TDMA system. 3 (A) shows the full division of time divided into a series of adjacent frames, in one embodiment having the same duration. Three complete continuous frames are shown in FIG. 3 (A). For system timing control, a synchronization channel is provided for user reference as needed. In another embodiment, each signaling segment starts with a frame marker signal from the base station to synchronize all remote user terminals to the base station's timing sequence.

One aspect of the present invention mainly relates to signal placement within each frame, and thus a representative frame (frame N) is shown in FIG. 3 together with the end of the previous frame (frame N-1) and the beginning of the next frame (frame N + 1). It is shown in more detail in B).

A frame according to an embodiment of the TDMA system of the present invention is again back to the selected number of downlink data transmission periods (time slots) D1, D2, D3, and the selected number of uplink data transmission periods (time slots) U1, U2, and the like. Divided. On the uplink, there are a number of acknowledgment transmission periods (timeslots) AKD1, AKD2, AKD3, etc., one associated with each downlink data transmission period and associated with the downlink data transmission period known to the base station. It has a predetermined relationship and is fixed in one embodiment. Also on the uplink, there are a number of acknowledgment transmission periods (type slots) AKU1, AKU2, etc., one associated with each uplink data transmission period and associated with the uplink data transmission period known to the base station and predetermined Relationship and one embodiment is fixed. For one embodiment of a TDMA system, a fixed relationship between a data transmission period and its associated acknowledgment transmission period is specified by a type slot. That is, the particular type slot of the data traffic period determines the timeslot of the associated acknowledgment transmission period in the opposite direction. Also, in one embodiment, this relationship is the same for the set of modes of consecutive time zones for all base stations in the system.

Note that, for an embodiment of a TDMA system, each data transfer period corresponds to a normal channel.

In the example shown in Fig. 3B, there are four uplink acknowledgment transmission periods because there are four downlink data transmission periods, and two downlink acknowledgment transmission periods because there are two uplink data transmission periods.

Recalling that SDMA systems facilitate the convenience of one or more communication channels, called spatial channels, during the same timeslot, the example of FIG. 3 (B) is at least communicating on the uplink with at least four active user terminals communicating on the downlink. Corresponding to accommodating two active user terminals.

One feature of the sequence of time intervals is that they can accommodate different numbers of data transmission periods on the uplink and downlink. In data communications, for example, when a base station is connected to a computer network such as the Internet, more communication typically occurs on the downlink than on the uplink. One aspect of the present invention is to accommodate asymmetry (unbalance) between downlink traffic data communication and uplink traffic data communication. The system may include more or less the number of each type of period shown here, depending on the number of active user terminals to be accommodated in a particular channel and the data transmission requirements and capabilities of the system in each direction. For higher data rates, a larger number of users in any direction may be accommodated by various embodiments of the present invention.

In another embodiment, since the same number of uplink and downlink data transmission periods exist in each sequential time interval, the total data transport capacity of the set of provided downlink traffic channels is determined by the total number of uplink traffic channels provided. Equivalent to the total data transport capacity of the set.

Downlink traffic  Communication( Downlink Traffic Communication )

After the paging is successful, the access assignment message from the first base station 102 is sent out of a time interval that continues the acknowledgment transmission period (ie, associated uplink channel) associated with the downlink transmission period (ie, downlink traffic channel). One set is allocated within each successive time interval.

Each user terminal that has been successfully paged (eg, receives an access assignment message as a result of initial downlink paging from an associated base station) on the uplink in an acknowledgment transmission period corresponding to its assigned downlink traffic transmission period. Respond to the paging sequence (eg, access assignment message). The first set and the further set of consecutive time intervals are up for an initial downlink paging sequence (e.g., an access assignment message) that includes a response from a user terminal of another base station, such as two base stations 11. The response of the user terminal on the link is to occur in a response general channel known to the first base station 102-for example, the transmission period and the frequency / signal channel. In particular, in one embodiment of a TDMA system, the timing of the base stations is synchronized, and the response of any desired user terminal is either the first base station 102 or another base station 111, which may occur in the same frequency channel and downlink data transmission period. ) Is aligned in time with the possible response of any interfering user terminal, such as other co-channel user terminals associated with the < RTI ID = 0.0 >

The acknowledgment signal sent from the user terminal to the associated base station includes some training data and some identification information. In one embodiment, the training data includes identification information. This identification information allows the first base station 102 to distinguish between signals from its associated user terminal and signals from user terminals of other base stations. The identification information includes a base station identifier. The first base station 102 receives the response (ie the acknowledgment signal) and uses the training signal and the identification information to transmit data during the next-down downlink data transmission period in a future-one embodiment for the user terminal. Determine smart antenna processing strategy for

The preferred smart antenna processing strategy of the first base station 102 for transmitting downlink traffic data to the user terminal is determined to include interference mitigation directed to the cochannel interferer, such that interference from the transmitting base station to the other cochannel user terminal is reduced. Is relaxed. Further, in one embodiment, the preferred smart antenna processing strategy for receiving an acknowledgment signal from the user terminal is determined to include interference mitigation from co-channel interferers.

In one embodiment, the acknowledgment signal includes an acknowledgment message (ACK) for causing the base station to signal to the user terminal and send back to the base station that the signal has been successfully received. If the base station does not receive the expected ACK or receives information that the message was not successfully received, the base station reschedules the data transmission.

The first base station 102 transmits data (ie traffic data) to the user terminal during the designated downlink data transmission period. The active user terminal receives downlink traffic data from the first base station 102. In one embodiment, the downlink signal sent to the user terminal, in addition to carrying traffic data, acts as a downlink polling signal to obtain a response on the uplink that determines a smart antenna processing strategy for other communications. Therefore, in response to downlink traffic data, the user terminal sends an acknowledgment signal back to the base station during the next acknowledgment transmission period in the designated downlink data transmission period. The base station receives this acknowledgment signal and also receives acknowledgment signals from one or more co-channel user terminals assigned to the same downlink data transmission period, and uses these signals received from the user terminal for the user terminal. A smart antenna processing strategy is then determined that can successfully transmit data to the user terminal for the next designated downlink data transmission period. The determined downlink smart antenna processing strategy includes interference mitigation sent to the co-channel remote terminal of the other base station 111. In addition, the first base station 102 determines a processing strategy for the smart antenna system to favor acknowledgment signals from the desired and interfering cochannel remote terminals, which are intended to include interference mitigation from interfering cochannel users. Receive. According to one embodiment of the invention, if the system provides more than one spatial channel in the same general channel, i.e. the same timeslot of the TDMA system, the determined smart antenna processing strategy is the same on other spatial channels of the same general channel. Interference mitigation for interfering remote terminals of the co-channel of base station 102.

Note that, in a predetermined acknowledgment transmission period for receiving an acknowledgment signal from the user terminal, the first base station 102 may be a response to a paging sequence (eg, an access assignment message) or downlink traffic data. Receiving an acknowledgment signal from the user terminal.

When downlink data transfer is thus started, downlink traffic data transfer continues on a frame-by-frame basis within the specified downlink data transmission period. Each downlink data signal also acts as a downlink polling signal. The user terminal receives the downlink data from its associated base station in the designated downlink data transmission period and sends an acknowledgment signal back to the base station for the next designated acknowledgment transmission period. The base station receives the acknowledgment signal with another acknowledgment signal sent from another co-channel user terminal of the same or another base station, and again the base station transmits the designated downlink data to optimally receive the acknowledgment signal. The processing strategy for the smart antenna system is determined to optimally transmit the next downlink data signal in the period. The base station receives an acknowledgment signal from the interfering user terminal, while optimally using a downlink strategy to mitigate interference from or to the interfering user terminal to enhance communication with one or more user terminals.

Thus, if the determination of a smart antenna processing strategy is to use the received signal during a special acknowledgment transmission period and to transmit data during the next downlink data transmission period associated with the special acknowledgment transmission period, the next downlink data The set of active user terminals transmitted during the transmission period is a subset of the set of user terminals transmitted to each base station during the previous special acknowledgment transmission period. In one embodiment, only user terminals that have received a signal in a previous special acknowledgment transmission period are transmitted on the downlink in a subsequent associated downlink data transmission period. Therefore, an active (i.e., not idle) user terminal transmitted from or to a base station during a particular period of downlink data transmission periods may be used during a previous acknowledgment transmission period on the uplink associated with the same particular downlink data transmission period. It is intended to have data initially transmitted to the base station.

From user terminal Uplink  Start communication

According to another aspect of the invention, communication initiation on the uplink is provided from one of the user terminals associated with the first base station 102. When the user terminal attempts to start data transmission to the first base station 102, the user terminal first transmits a random access request signal through an agreed-upon logical control channel, and the random access request The first base station 102 receives the signal. In response, the first base station 102 likewise transmits an access assignment message to the user terminal via the negotiated logical control channel, the access assignment message including transmission information informing the user terminal that the random access request signal has been received; It also includes data for specifying an uplink data transmission period and a frequency channel for receiving data transfer on the uplink from the user terminal.

In response, the user terminal transmits uplink traffic data during the designated uplink traffic transmission period. The base station receives uplink data from the user terminal. User terminals of other base stations, such as the second base station 111, may also transmit uplink traffic data to each base station, which may interfere with the uplink signal transmitted to the first base station 102. In addition, if the first base station 102 also provides SDMA, other related user terminals sharing an existing channel may also interfere in that way. In one embodiment of the present invention, since the uplink data acts as a response to the access assignment message from the base station and is provided to the first base station 102, the signal from the user terminal using the response (ie, uplink traffic data) is used. Determine a smart antenna processing strategy for receiving the. According to one such embodiment, the first set and the other set of consecutive time intervals are configured such that the uplink traffic signal is either in response to an access assignment message or while continuing to transmit uplink traffic data. Is designated to be transmitted on an uplink general channel, for example, a data transmission period and a frequency / signal channel. The first base station 102 receives the uplink traffic signal using a smart antenna processing strategy determined according to the received signals. The smart antenna processing strategy is to receive a data signal from its associated active user terminal. In one embodiment, each uplink traffic data signal within a designated uplink data transmission period includes training data to provide information to a base station that determines a processing strategy for the smart antenna system. Training data includes identification information. In one embodiment, the smart antenna processing strategy causes the control computer to receive the uplink data well within the same uplink data transmission period. In another embodiment, where the control computer does not have sufficient computing power to quickly determine an uplink smart antenna processing strategy that is sufficient to optimally receive data during the same uplink data transmission period, the smart antenna system may not be able to determine one uplink data. Using an uplink strategy that determines from the data received within the transmission period, data is sent in the uplink data transmission period of a future frame during a future-for example, next-uplink data transmission period for a particular user terminal. Receive. In an embodiment of the TDMA system, the timing of the base stations is synchronized and the uplink data transmission period of the desired user terminal and the co-channel user terminals transmitting to each base station of the user terminal are the same in the same timeslot and in the same frequency channel. Can happen in

In one embodiment, when the base station successfully receives uplink traffic data from an active user terminal, the base station sends an acknowledgment signal to the user terminal on the downlink for the uplink data transmission period during the designated acknowledgment transmission period. . The uplink traffic data signal is therefore used as a reverse polling signal from the user and the response to this is an acknowledgment signal from the base station, which can be considered as a reverse polling acknowledgment signal after communication has commenced. The base station uses the response to the other reverse polling acknowledgment signal (ie, for the acknowledgment signal from the base station) to determine further processing strategies for the smart antenna system.

In one embodiment, to increase the likelihood that an acknowledgment signal on the downlink will be successfully received at the user terminal, the first base station 102 uses the uplink traffic data to be verified, and then the next designated acknowledgment on the downlink. In order to better transmit an acknowledgment signal to the user terminal in the period, a processing strategy for the smart antenna system is determined. The determined processing strategy includes interference mitigation sent to one or more cochannel user terminals of another base station or first base station 102 from which the first base station 102 receives uplink traffic data.

In one embodiment, the acknowledgment signal sent from the first base station 102 to the user terminal provides the user terminal with an acknowledgment message (ACK) as feedback for successfully receiving at the base station. This acknowledgment message may be a negative acknowledgment message (NACK) or some other feedback signal. If the user terminal receives a NACK or does not receive the expected ACK, or if the information that the message was not received is somehow fed back, the user terminal changes the schedule for the transmission of data. In addition, the acknowledgment signal may include training data to help successful reception of the user terminal. Further, in one embodiment, the one or more user terminals may comprise a smart antenna system, in which case the acknowledgment in traffic from the downlink to the uplink is a smart antenna processing strategy for the smart antenna system of the user terminal. Can be used to determine

Uplink communication from the user terminal to the first base station 102 may continue to transmit frame by frame in the designated uplink data transmission period. Each uplink data received by the base station, along with any co-channel uplink traffic data from other interfering user terminals, is smart at the first base station 102 for receiving data from the user terminals. The processing strategy for the antenna system can be determined. The base station may also determine a processing strategy for its antenna system and transmit the acknowledgment signal to the associated user terminal as a reverse poll acknowledgment signal.

Although an embodiment of the present invention addresses the case of one base station having a smart antenna system, according to another embodiment, the communication system 100 may include a plurality of base stations each including a smart antenna system. In one embodiment, the first base station 102 and the one or more second base stations 111 use the same set of consecutive time intervals configured, wherein the first set and the further set of consecutive time intervals have the same structure. .

 The signal shown in FIG. 3B is used in a TDMA system including a TDD, grouping uplink signals and downlink signals, thereby reducing the number of switching of the smart antenna system of the base station from the uplink to the downlink. You can. For the signal shown in Fig. 3B, the order of the time zones can be changed when the base station uses frequency domain duplexing (FDD). The downlink frequency and the uplink frequency are different from each other even when communicating with the same user terminal. One example thereof is shown in Fig. 3D. FIG. 3E shows another example similar to the configuration of FIG. 3B but in which the frame boundary is changed. Many other examples of the configuration of FIG. 3B can be implemented without departing from the scope of the present invention as set forth in the claims below.

Another embodiment of traffic communication

The embodiment using the frame structure shown in FIG. 3 implements a half duplex in which any uplink data transmission period of a frame set does not necessarily have to be associated with a downlink data transmission period for the same user terminal. Yes.

According to the half-duplex embodiment, the acknowledgment transmission period in one frame of the frame sequence for acknowledgment uplink data transmission is included in the next designated downlink data transmission period for the user terminal. Thus, data transmitted on the downlink during the downlink data transmission period may include acknowledgment data and / or training data. In addition, there is a downlink data transmission period for each uplink data transmission period.

Further, according to another embodiment of the half-duplex scheme, in the acknowledgment transmission period in the frame for acknowledging the downlink data transmission (or for responding to the access assignment message), the next designated down for the user terminal is specified. Included in the link data transmission period. Thus, data transmitted during the uplink data transmission period may include training data and / or identification data and / or acknowledgment data. In addition, there is an uplink data transmission period for every downlink data transmission period.

4 is a timing diagram illustrating a transmission sequence in another embodiment using the full duplex method (referred to as a 'full duplex embodiment'). 4 (A) shows that time is divided into a series of consecutive frames in the same section. Three complete sequential frames are shown in Fig. 4A.

An example of a data transmission segment for a particular channel is shown in detail in FIG. 3 (B). The frame according to the full-duplex embodiment is partially divided into the same number of downlink data transmission periods (D1, D2, D3, etc.) as a plurality of uplink data transmission periods (U1, U2, U3, etc.). In the example shown in Fig. 4B, there are five downlink and uplink data transmission periods corresponding to at least five active user terminals. Each active user terminal is assigned to uplink and downlink data transmission periods, as disclosed herein by using an access assignment message from an associated base station. In other embodiments, each frame may have a greater or fewer downlink and uplink data transmission period. For example, the embodiment uses a frame structure in which each frame includes three uplink and three downlink data transmission periods.

According to the implementation of the full duplex method, the acknowledgment transmission period in one frame of the sequence of time intervals for acknowledging the uplink data transmission is the downlink data transmission specified in the future, preferably next time, to the user terminal. Included in the period. Further, the acknowledgment transmission period in one frame of the sequence of time intervals for acknowledging the downlink data transmission (or for responding to the access assignment message) is specified in the future, preferably next time, for the user terminal. Included in the uplink data transmission period.

Initialization of data communication from the base station is performed as described above with respect to the half-duplex embodiment disclosed herein. The base station first transmits a paging message. In response, the user terminal responds with a Lambdon access request. The base station responds with an access assignment message that includes the ability to specify uplink and downlink time zones for use in traffic communication.

When the user terminal receives the access assignment message, it transmits an acknowledgment signal during its assigned uplink traffic channel. This acknowledgment signal may include training data and / or identification data for use in determining an effective smart antenna processing strategy for the wireless link connecting the user terminal and the base station at the associated base station. Since the series of consecutive time zones for the first base station 102 functions in conjunction with a series of consecutive time zones for other base stations (eg, the second base station 111), the response to the access assignment message from the user terminal is timed. For a base station that knows the frequency location. Thus, the base station (e.g., the first base station 102) receives a signal such as an interference signal not only from the associated user terminal, but also from the co-channel user terminal associated with another base station (e.g., the second base station 111). An effective smart antenna processing strategy for communicating with the user terminal is determined to include interference mitigation from the cochannel interferer (if uplink) and interference mitigation to the common channel interferer (if downlink).

In addition, when the base station receives uplink traffic data from one or more related user terminals, the base station transmits an acknowledgment signal to the user terminal in the downlink data transmission period corresponding to the uplink data transmission period in which the uplink data is received.

Thus, the signal is transmitted by the user terminal not only in response to an access assignment message from the associated base station, but also as an acknowledgment for downlink traffic data received from the associated base station.

Further, according to a full duplex embodiment, the uplink traffic data includes training data and identification data, and the base station uses these data to determine a processing strategy for the smart antenna system.

Thus, data transmitted on the downlink during the downlink data transmission period may include training data and acknowledgment data (ACK and / or NACK data) or other mechanism for acknowledgment. The data transmitted during the uplink data transmission period may include training data and / or identification data and / or acknowledgment data (ACK and / or NACK data) or other acknowledgment data. If the transmitting entity receives a NACK or does not receive the expected ACK or finds that the reception was not successful, the entity changes the transmission schedule of the data.

Another embodiment of the present invention will be described. According to this embodiment, in the case of initiating communication from the base station, the base stations 102 and 111 respectively transmit downlink polling signals for each of these user terminals before receiving data transmissions from the associated active user terminals. send. Such polling is used to facilitate the determination of a smart antenna processing strategy for a particular packet data communication, in accordance with an embodiment of the present invention. In one embodiment, polling for the downlink is within a first set of sequential time intervals for the first base station 102 and within another set of sequential time intervals for each of the second base stations 111. , By a first base station 102 and one or more second base stations 11. Each of these time intervals includes a selected number of downlink transmission periods including a forward polling period, a plurality of uplink transmission periods associated with the forward polling period, and a data transmission segment having a plurality of traffic data transmission periods.

5 is a series of transmission timing diagrams illustrating a transmission sequence in the case of this alternative embodiment. FIG. 5A is a diagram of dividing the entire time into a sequence of consecutive frames of the same duration. Each frame includes a signaling segment for transmitting and receiving a system overhead signal such as cellular overhead, and a data transmission segment. In Fig. 5A, three complete sequences of frames are shown. To control system timing, each signaling segment is initiated with a frame marker signal from the base station to synchronize all remote units to the base station's timing sequence.

One aspect of the invention relates primarily to the arrangement of signals within the data transmission segment of each frame, and thus an example data transmission segment for a particular channel is shown in detail in FIG. 5 (B).

A data transmission segment according to another embodiment of the present invention is added to a plurality of forward polling periods F1, F2, F3, etc., a plurality of reverse polling periods R1, R2, R3, etc., a plurality of traffic data transmission periods D1, D2, D3, etc. Divided. In the example shown in FIG. 5B, there are five forward polling periods, five reverse polling periods, and five traffic data transmission periods, corresponding to the acceptance of at least five active user terminals. Each active user terminal is assigned a signal channel, a forward polling period, and a reverse polling period.

The first base station 102 and the other base station 111 transmit their downlink polling signal in their respective forward polling periods. Each user terminal receiving a polling signal from a base station associated with it responds to the polling signal in an uplink transmission period associated with a forward polling period. The associated uplink transmission period is part of the traffic data transmission period of a set of consecutive time intervals of base stations associated with it. The first and additional set of successive time intervals is such that the response of the user terminal to downlink polling occurs in the associated uplink transmission period and frequency / code channel known to the first base station 102.

The first base station 102 receives the response, uses the response to determine the downlink processing strategy for the smart antenna system, and transmits the data signal to an active user terminal associated with it using the determined downlink processing strategy. do. In one TDMA embodiment, the timing of the base stations is synchronized and such user terminals for downlink polling from each base station of the requested user terminals 105, 106, 107, 108 and the interfering user terminals 109, 110. Response occurs in the same timeslot and the same frequency channel. The determined smart antenna processing strategy includes interference mitigation towards the interfering co-channel remote terminal.

When the user terminal wishes to send a data transmission to the first base station 102 to initiate communication from one of the user terminals associated with the first base station 102, the user terminal is received by the first base station 102. The reverse polling signal is transmitted during the reverse polling period. The first base station 102 receives, to the user terminal, a reverse poll acknowledgment signal, transmission information and traffic data transmission period for indicating to the user terminal that the reverse poll has been received, and data transmission through the uplink from the user. It transmits with data for specifying a frequency channel.

The user terminal then sends a data transmission signal during the designated uplink traffic data transmission period. The data transmission signal may include training data in the training data segment of the uplink traffic data transmission period as shown in FIG. 5D. The base station receives a signal from the user terminal. Other base stations, such as the second base station 111, may also receive signals in response to a reverse polling acknowledgment from their respective base stations, which may interfere with data transmission signals for the first base station 102. It may be. According to one embodiment of the invention, the first and additional sets of consecutive time intervals are in response to an uplink traffic data transmission period known to the first base station 102 and a reverse poll acknowledgment signal in the frequency / code channel. A data transmission signal is made to be sent.

The first base station 102 then receives the data signal from the active user terminal associated with it using the determined smart antenna processing strategy. In one embodiment of the TDMA scheme, the timing of the base stations is synchronized and for such reverse poll acknowledgments from each base station of the desired user terminals 105, 106, 107, 108 and the interfering user terminals 109, 110. The response of the user terminal occurs in the same timeslot and the same frequency channel. The smart antenna processing strategy is determined to include interference mitigation from such interfering users.

In one embodiment, system 100 includes a first base station 102 and one or more other base stations 111, each of which has a smart antenna system. The first base station 102 and the other base station 111 use a series of contiguous time intervals configured identically, so that the first and additional sets of successive time intervals have the same structure. In another embodiment, only the first base station 102 has a smart antenna system.

As an alternative to the signal shown in Fig. 5B, it may be advantageous to first provide a reverse polling period and then a forward polling period as shown in Fig. 5C. In this case, the base station may acknowledge receipt of the reverse polling signal from the user terminal and designate the data transmission segment by the selected reverse poll acknowledgment signal during the corresponding forward polling period. In the case of forward polling, as described above, the acknowledgment is required because the transmission of the training signal by the user terminal at the beginning of the data transmission period sufficiently informs the base station that the user terminal has received the forward polling signal. It doesn't work.

Other embodiments may use different ways of increasing the likelihood of successful reception at the remote terminal for overhead signaling and polling signals sent by the base station. In one other embodiment, the overhead signaling and polling signals are transmitted via wide-area beams using the elements of array 104 (for example, US patent application filed on December 12, 1997 and assigned to the applicant). 08 / 988,519).

Another embodiment may further use a pilot tone rather than a training signal in response to the user terminal. Other embodiments may not include a training signal or pilot tone, in which case a known " blind " method may be used to determine weighting parameters for the smart antenna system of the first base station 102. have.

In other embodiments, modifications may be made to other known polling devices to obtain weighting parameters for the smart antenna system of the base station. An example protocol that may be modified is the protocol proposed in the following literature: "Performance of a modified polling strategy for broadband wireless LANs in a harsh fading environment," Proc. GLOBECOM'91, ("Zhang"); "New adaptive MAC layer protocol for wireless ATM networks in harsh fading and interference environments," by A. S. Amapora and S. V. Krishnamurthy, Proc. ICUPC'97, San Diego, CA, 1997 ("Amapora and Krishnamurthy"); "Polling based media access protocol for use with smart adaptive array antennas," by S. V. Krishnamurthy, A. S. Amapora and M. Zorzi. ICUPC'98, pp. 337-341, 1998 ("Krishnamurthy"). Zhang proposes a token-based protocol that allows the base station's smart antenna system to periodically update its weighting parameters by sequentially polling each remote terminal. The remote terminal responds to the polling request using either an information request or an unmodulated pilot tone, and one response may be used to update the weight. In order to modify Zhang's method and incorporate it into the present invention, the protocol used by one base station and one or more other base stations may include information requests or unmodulation received from remote user terminals of other base stations, such as the second base station 111. The pilot signal is adjusted to occur at a time / frequency location known to the first base station 102, and provided to provide interference mitigation for a user terminal associated with another base station or to provide interference mitigation from a user terminal associated with another base station. 1 is used to determine the processing strategy for the smart antenna system of base station 102. Amapora and Krishnamurthy are proposing a media access (MAC) protocol that claims to be capable of faster adaptation than Zhang. Each transmission in both directions is initiated immediately by a remote terminal remotely located with respect to the base station pilot signal, which base station pilot signal is used to immediately adapt the array to that remote remote terminal. Modifications of the Amapora and Krishnamurthy methods will be similar. In the Krishhamurthy scheme, any remote terminal may send its information request to any information transfer between the base station and itself. Therefore, in the current frame, only remote terminals that did not transmit information in the previous frame are polled. Thus, the frame size is not fixed and varies at least with the number of poles included. In one variant, the base station uses limited polling in that the remote terminal sends one request to each base station in each poll, and in the second variant, the base station polls each remote terminal altogether, Send all of your requests when polled. The modified Krishnamurthy scheme is another embodiment of the present invention in which the protocol used by a particular base station is adjusted through the protocol used by another base station, such that a response by a remote terminal occurs at a time / frequency location available to that particular base station. It may be used in the example.

While much of the foregoing description has been made with respect to TDMA systems, the present invention may also be practiced with FDMA systems and CDMA systems.

The invention may be employed in the form of hardware, software or a combination thereof, for example in one embodiment, the invention is at least partly employed in a device (eg, a data processing system employed by a communication device such as a base station or a user terminal). Information, indicative of a set of instructions that, when executed, causes the device to perform at least a portion of the method implemented by the present invention, will be implemented by information read from a stored readable medium. Readable media may include storage media (eg, magnetic storage disks, optical disks, etc.) and / or memory elements (eg, ROM, RAM, DRAM, SRAM, etc.). One or more general purpose processors and / or dedicated processors, such as digital signal processing units (DSPs), may be employed by base stations or user terminals operating in conjunction with embodiments of the present invention.

The user terminal in the present invention represents various types of communication devices and connects to input and / or output devices and processing devices to provide various types of functionality such as voice communication and data communication via the Internet or other data communication networks. May be

Although the present invention has been described in terms of communications, in particular a cellular communication system employing at least one base station with a smart antenna system, the invention is not limited to this and includes various wireless applications and systems, such as smart antenna systems. It may be used in a system including a communication device such as a communication station. In addition, the present invention is not limited to any one type of architecture or air interface, but may be used with one or a combination of TDMA, FDMA or CDMA and TDD or FDD, or other architectures / protocols. will be.

Therefore, although the preferred embodiments of the present invention are disclosed herein, those skilled in the art will recognize that modifications or changes may be made to the present invention without departing from the spirit of the present invention. All such modifications or variations are also included in the spirit of the present invention.

Claims (68)

A paging signal transmission method for transmitting a paging signal within a frame defined by a communication protocol, The frame is a group of consecutive data transmission periods, and the data transmission period is composed of a plurality of sub-periods, The paging signal transmission method, Transmitting the paging signal in the sub-period of the data transmission period of the first frame; And A repetitive transmission step of repeatedly transmitting the paging signal in a sub period at a position different from the one sub period of the first frame in a second frame so as to be differentiated from the transmission of the paging signal in the transmission step Paging signal transmission method comprising a. The method of claim 1, And the transmitting step comprises transmitting the paging signal to a sub-timeslot of the data transmission period. The method of claim 1, And the transmitting step comprises transmitting the paging signal in a sub-frequency-band of a data transmission frequency band. The method of claim 1, The repetitive transmission step, Determining a number of times to retransmit the paging signal based at least on proximity of the receiver to the transmitter; And And a retransmission step of retransmitting the paging signal a number of times determined in the determining step. The method of claim 4, wherein And the determining step includes estimating a proximity of the receiver from an amount of interference of interference appearing in an initial registration sequence. The method of claim 1, Adjusting signal transmission characteristics after the transmission of the paging signal according to a change in the interference environment associated with the paging signal. The method of claim 1, Adjusting a signal transmission characteristic prior to repetitive transmission of the paging signal according to a change in an interference environment associated with the paging signal. A computer readable medium, Transmitting a paging signal in any sub period of the divided data transmission period in the first frame, wherein the data transmission period is composed of a plurality of sub periods; And In a sub-period at a position different from any one sub-period of the first frame in a second frame, to be differentiated from the transmission of the paging signal in the transmitting step, to be differentiated from the transmission of the paging signal in the transmitting step. A repetitive transmission step of performing repetitive transmission of the paging signal And instructions for instructing to perform. The method of claim 8, The repetitive transmission step, Determining a number of times to retransmit the paging signal based at least on proximity of the receiver to the transmitter; And And retransmitting the paging signal a number of times determined in said determining step. The method of claim 8, And instructing to adjust a signal transmission characteristic after the transmission of the paging signal in accordance with a change in the interference environment associated with the paging signal. The method of claim 8, And instructing to adjust a signal transmission characteristic prior to repetitive transmission of the paging signal in accordance with a change in the interference environment associated with the paging signal. A paging signal transmission device for transmitting a paging signal within a frame defined by a communication protocol, The frame is a group of consecutive data transmission periods, and the data transmission period is composed of a plurality of sub periods, The paging signal transmission device, Transmitting means for transmitting the paging signal to any sub period of the data transmission period of the first frame; And In a sub-period at a position different from any one sub-period of the first frame in a second frame so as to be differentiated from the transmission of the paging signal in the transmitting step so as to be differentiated from the transmission of the paging signal by the transmitting means. Repetitive transmission means for repetitive transmission of the paging signal Paging signal transmission device comprising a. The method of claim 12, And said transmitting means comprises means for transmitting said paging signal to a sub timeslot of a data transmission period. The method of claim 12, And said transmitting means comprises means for transmitting said paging signal to a sub frequency band of a data transmission frequency band. The method of claim 12, The repeat transmission means. Determining means for determining a number of times to retransmit the paging signal based at least on proximity of a receiver to a transmitter; And And retransmitting means for retransmitting said paging signal a number of times determined in said determining step. The method of claim 15, And the means for determining comprises means for estimating the proximity of the receiver from the amount of interference of interference appearing in an initial registration sequence. The method of claim 12, Means for adjusting a signal transmission characteristic after transmission of the paging signal in accordance with a change in an interference environment associated with the paging signal. The method of claim 12, Means for adjusting a signal transmission characteristic prior to repetitive transmission of the paging signal in accordance with a change in the interference environment associated with the paging signal. delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete

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