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The correction factors can be described as amplitude and phase corrections or corrections in in-phase and quadrature components, or shorter I- and Q-components. When calibrating the antenna array that transmits communication signals according to the invention only one single calibration receiver is used. If the calibration network and the calibration receiver are not capable of separating the information from different transmitting antenna sections, each transmitting antenna section has to be separately calibrated one at a time.
In a first embodiment of the transmission calibration the same calibration signal is used for calibrating all transmitting antenna sections.
This means that the calibration controller comprises only one signal generator. If all transmitting antenna sections were to send the same signal simultaneously the single calibration receiver would interpret the sampled data as one signal and therefore not be able to distinguish data from separate transmitting antenna sections.
Hence each of the transmitting antenna sections has to be calibrated separately in time in this example. The calibration signal S 2 t 1 is first injected into a first, reference, transmitting antenna section A 1 at a first time t 1.
The calibration network samples this transmitting antenna section when the calibration signal has passed the transmitting components T 1. The distorted signal y 1 t 1 is received at a first collection time by the calibration receiver Thereafter the same calibration signal S 2 t 2 is injected into a second transmitting antenna section at a second time t 2. The second transmitting antenna section A 2 is sampled and the phase and amplitude distorted signal y 2 t 2 is received by the calibration receiver A compensated correction factor is generated by the calibration controller for the second transmitting antenna section relative the correction factor of the reference antenna section, according to the same method as was described in conjunction with steps - in FIG.
The same calibration signal is injected into the rest of the antenna sections, one at a time, and correction factors are generated for each of the transmitting antenna sections. When calibrating the antenna array the transmitting antenna sections preferably should be related to the limiting transmitting section, that is the antenna section that outputs the lowest power.
The limiting transmitting antenna section is found by finding the compensated correction factor with the largest amplitude. During normal operation of the antenna array the transmitted power can be controlled so that all power amplifiers are guaranteed to work within their dynamic range. As the calibration of each transmitting antenna section is performed at different times the calibration is sensitive to time errors.
If the time between the calibration signal is injected and sampled is not the same for all transmitting antenna sections, a time error will be introduced.
This time error will be interpreted as a phase error when computing the correction factors. The phase error that is computed according to the method described in conjunction with FIG. Time errors can occur due to several reasons, depending on the hardware implementation.
If, for example one transmitting antenna section delays the sending of a signal, a constant time error could be introduced. For such a time error one might want to adjust the time base in the transmitting antenna sections. For other situations it might suffice to eliminate the phase error caused by the time error from the estimated phase error.
To estimate time errors a special calibration signal could be chosen when calibrating the transmitting antenna sections, according to one embodiment of the present invention. This signal has a positive and negative phase slope during the data collection interval for each transmitting antenna section. One example of such a calibration signal is a signal with linear phase, with positive phase slope during a first time interval and then with the same phase slope but negative during a second consecutive time interval.
In FIG. The phase slopes have the same values with opposite signs:. The first calibration signal is injected into the reference section at an initial time t 0 and a first sample is taken when the phase slope is positive, at a time t 1. A second sample is taken when the phase slope is negative at a time t 2.
In reality several samples are collected for the positive and for the negative slope. For simplicity only one sample per slope is shown in the figure.
In this example the intended time between injection in two different transmitting antenna sections is a constant t c. The first antenna section is then calibrated in a time slot in a first TDMA-frame and the next antenna section is calibrated in the same time slot in the following TDMA-frame.
The time between two consecutive corresponding injections of the calibration signal and samples should then also be tc. This is denoted as the real phase error. The dashed line in FIG.
A relative, compensated phase error relating the phase error of the second antenna section to the reference antenna section can be generated according to the method described in conjunction with FIG. If these equations are combined the real phase error and the phase error introduced by the time error are found to be:.
The real phase error will be used in the correction factor. The phase slope of the traffic signals may differ from the phase slope of the calibration signal. By using the formula 7. In a second embodiment of the calibration of the transmitters the transmitting antenna sections are capable of simultaneously transmitting different calibration signals and still perform a separate calibration for each of the transmitting antenna sections. The calibration controller then generates different simultaneous signals that are mutually orthogonal.
Examples of orthogonal signals are signals of different frequencies or signals modulated with orthogonal codes, for example Walsh-Hadamard codes or orthogonal Gold codes. This implies that the calibration controller comprises one signal generator for each of the transmitting antenna sections.
This solution is therefore more hardware demanding. On the other hand it is less time consuming. The orthogonal signals are simultaneously injected into a respective transmitting antenna section. The resulting signals are then passed through the calibration network and received by the single calibration receiver in parallel, that is simultaneously, after having passed through the phase and amplitude distorting components of the transmitting antenna sections.
The collected signals are superimposed in the calibration network and received in the calibration receiver as one composite signal. Since the signal components are orthogonal, the calibration controller can separate the individual signals and compute correction coefficients of phase and amplitude. When generating the correction factors in this case the received signals from the calibration receiver have to be related to the original transmitted signals for each antenna section.
This implies that the injection of a calibration signal and the sampling of the corresponding signal are synchronized. The information about the transmitted signal must be buffered and available during the generation of correction factors. The calibration of the antenna array according to this invention is intended to be performed during normal traffic, such that the traffic is not affected or very little affected by the calibration.
The correction factors are frequency dependent. This means that correction factors for different frequencies must be generated. However, for frequencies within the same coherency bandwidth it suffices to compute one set of correction coefficients for one frequency within that band.
The frequency spectrum is therefore divided into a number of frequency bands, each band narrower than the coherency bandwidth. Each band is then calibrated separately. The calibration could be performed on-ine without disturbing the normal traffic flow in one of the following ways:.
In this case a short period of time is stolen from a normal traffic channel and the traffic on that channel will be disturbed for a short while. However that might have minor effect on for example speech quality;. In this case normal traffic is not disturbed but a new call could be delayed for a very short period of time;. In this case the traffic flow is non interrupted. The calibration controller then comprises a correlation receiver. The duration of the spread spectrum signal is chosen so that the processing gain can suppress the normal traffic signal in the correlation receiver enough to facilitate accurate estimation of the calibration factor.
The spread spectrum signal might introduce some interference to the traffic channels but the power is chosen low to limit the interference. The method for calibration of the transmitting and receiving antenna sections of an antenna array according to the present invention could be continuously performed in the system or at specific time intervals. In a TDMA-system a channel is defined by a time slot and a frequency.
In a first embodiment of the calibration of a TDMA-system, according to option a , the calibration of the antenna array is performed by stealing time slots from traffic channels.
Instead of handling the normal traffic signals the calibration signal is then injected and correction factors computed. In another embodiment of the calibration of an antenna array in a TDMA-system, according to option b , free time slots dedicated to traffic channels are used for calibration. This could be the time between one call terminates and the next is set up on the same slot.
Calibration could then be made every time a call has terminated, which should be sufficiently often to ensure that the correction factors are reliable. In a frequency hopping TDMA-system all frequencies could be calibrated in one sweep. This means that samples could be collected for each frequency in a hop sequence while stepping through the sequence.
Data is thus collected for each frequency and calibration factors are estimated according to the method previously described. In a third embodiment of the calibration of an antenna array in a TDMA-system, according to option c , the calibration signal is a low-power spread spectrum signal that is injected into the normal signal flow.
This signal is collected and fed to a correlation receiver comprised in the calibration controller. In a CDMA-system a channel is defined by a special code. In a first embodiment of the calibration of an antenna array in a CDMA-system, according to option a , a code that is already in use for a traffic channel is stolen for a short period of time and the calibration is performed.
In another embodiment of the calibration of an antenna array in a CDMA-system, according to option b , a free code is used for calibration, for example between the termination of a call using a certain code and the set up of a new call using the same code. In yet another embodiment of the calibration of an antenna array in a CDMA-system, according to option c , a low-power spread spectrum signal is injected into the normal traffic flow.
This signal will have a code of its own and it will typically have lower power than the normal traffic signals. Data is collected over a longer period of time than what is needed if a normal traffic code is used. In a CDMA-system the number of possible codes are often more than the number of possible users, only a part of the possible codes are thus used in a CDMA-system. In a fully loaded system, that is when the maximum number of users are assigned to the system without exceeding the allowed interference level, there is always a possibility of overloading the system by using an unused code.
This will however lead to increasing interference in the system. According to one embodiment of the present invention a normal traffic code that is not to be used in the system is used for calibration. In a FDMA-system a channel is defined by a certain frequency. In a first embodiment of the calibration of an antenna array in a FDMA-system, according to option a , a short period of time is stolen from a traffic channel, for example from a frequency that is in use, and the calibration is performed.
In a second embodiment of the calibration of an antenna array in a FDMA-system, according to option b , free frequencies are used for a short period of time, for example the time between the termination of a call on a certain frequency and the set up of another call using that frequency. In a third embodiment of the calibration of an antenna array in a FDMA-system, according to option c , a low-power spread spectrum signal is superimposed on top of a specific carrier.
The present invention severely reduces the accuracies required of the components connected to each antenna section because the present invention measures and corrects for errors generated by these components. In addition, the system used for calibration simultaneously tests the devices associated with each antenna section so as to verify that the antenna array is working properly. The invention provides a method and apparatus for calibrating the antenna sections of an antenna array comprised in a base station.
The calibration can be performed essentially without interrupting or disturbing the normal traffic flow in the radio communication system. The calibration apparatus according to the invention only comprises one single calibration transmitter and one single calibration receiver, used to calibrate the whole receiving and transmitting antenna array. It will be appreciated by those of ordinary skill in the art that the present invention can be embodied in other specific forms without departing from the spirit or central character thereof.
The presently disclosed embodiments are therefore considered in all respects to be illustrative and not restrictive. The scope of the invention is indicated by the appended claims rather than the foregoing description, and all changes which come within the meaning and range of equivalence thereof are intended to be embraced therein.
We claim: 1. A method for calibrating an antenna array that transmits communication traffic signals during beamforming in a mobile radio communication system, said antenna array comprising a number of transmitting antenna sections each comprising transmitting components that might distort the phase and the amplitude of signals that are to be transmitted, said method comprising the steps of:.
A method for calibrating an antenna array according to claim 1 , where in said generation of correction factors comprises:. A method for calibrating an antenna array according to claim 1 , wherein said calibration signal has a positive phase slope during a first time interval and a negative phase slope during a second consecutive time interval, and wherein the calibration signal is sampled in the first and the second time interval, and wherein samples from the first time interval are compared with samples from the second time interval, in order to estimate a time error.
A method for calibrating an antenna array according to claim 1 , wherein said calibration signal is a pure sinusoid. A method for calibrating an antenna array according to claim 1 , wherein said generation of correction factors for each transmitting antenna section comprises the steps of:. A method for calibrating an antenna array according to claim 1 , wherein said correction factors compensate for signal errors introduced by the transmitting components in each transmitting antenna section, and for signal errors introduced by means used for calibrating the antenna array.
A method for calibrating an antenna array according to claim 1 , wherein said correction factors are limiting the signal power of transmitted signals. A method for calibrating an antenna array according to claim 1 , wherein said correction factors adjust the phase of the signals that are to be transmitted by the antenna sections.
A method for calibrating an antenna array according to claim 1 , wherein said correction factors adjust the amplitude of signals that are to be transmitted by the antenna sections. A method for calibrating an antenna array according to claim 1 , wherein said correction factors adjust the phase and amplitude of signals that are to be transmitted by the antenna sections. A method for calibrating an antenna array according to claim 1 , wherein the correction factors are applied to signals that are to be transmitted, after active beamforming.
A method for calibrating an antenna array according to claim 1 , wherein the calibration signal is a lower-power spread spectrum signal that is injected into the normal traffic flow. A method for calibrating an antenna array according to claim 1 , wherein the radio communication system is a CDMA-system with a predetermined number of codes that are allowed for use during normal traffic, wherein a code that is not intended to be used for traffic is used for calibration.
A method for calibrating an antenna array according to claim 1 , wherein said method is continuously repeated. A method for calibrating an antenna array according to claim 1 , wherein said method is repeated at certain time intervals. A method for calibrating an antenna array that transmits communication traffic signals during beamforming in a mobile radio communication system, said antenna array comprising a plurality of transmitting antenna sections each comprising transmitting components that might distort the phase and the amplitude of signals that are to be transmitted, said method comprising the steps of:.
A method for calibrating an antenna array according to claim 16 , wherein the calibration signals are of different frequencies. A method for calibrating an antenna array according to claim 16 , wherein the calibration signals are different orthogonal codes. A method for calibrating an antenna array according to claim 16 , wherein said calibration signal is a pure sinusoid. A method for calibrating an antenna array according to claim 16 , wherein said generation of correction factors for each transmitting antenna section comprises the steps of:.
A method for calibrating an antenna array according to claim 16 , wherein said correction factors compensate for signal errors introduced by the transmitting components in each transmitting antenna section, and for signal errors introduced by means used for calibrating the transmission of the antenna array. A method for calibrating an antenna array according to claim 16 , wherein said correction factors are limiting the signal power of transmitted signals.
A method for calibrating an antenna array according to claim 16 , wherein said correction factors adjust the phase of the signals that are to be transmitted by the antenna sections. A method for calibrating an antenna array according to claim 16 , wherein said correction factors adjust the amplitude of signals that are to be transmitted by the antenna sections.
A method for calibrating an antenna array according to claim 16 , wherein said correction factors adjust the phase and amplitude of signals that are to be transmitted by the antenna sections. A method for calibrating an antenna array according to claim 16 , wherein the correction factors are applied to signals that are to be transmitted, after active beamforming. A method for calibrating an antenna array according to claim 16 , wherein the calibration signal is a low-power spread spectrum signal that is injected into the normal traffic flow.
A method for calibrating an antenna array according to claim 16 , wherein the radio communication system is a CDMA-system with a predetermined number of codes that are allowed for use during normal traffic, wherein a code that is not intended to be used for traffic is used for calibration. A system for calibrating an antenna array that transmits communication traffic signals during beamforming in a mobile radio communication system, said antenna array comprising a number of transmitting antenna sections each comprising transmitting components that might distort the phase and the amplitude of signals that are to be transmitted, said system comprising:.
A system for calibrating an antenna array according to claim 29 , wherein said correction factors adjust the phase of signals that are to be transmitted by the antenna sections.
A system for calibrating an antenna array according to claim 29 , wherein said correction factors adjust the amplitude of signals that are to be transmitted by the antenna sections. A system for calibrating an antenna array according to claim 29 , wherein said correction factors adjust the phase and amplitude of signals that are to be transmitted by the antenna sections.
During this period, there was a linear infection. Based on the observed temporal changes of the increase in differentially expressed cellular genes and by 24 hpi, expression patterns, the adenovirus infectious cycle can be the expression of over cellular genes was altered.
About divided into four periods. At this time, the virus infection before any of the adenoviral genes had been expressed. At 6 hpi, had proceeded far into the early phase and the expression seven differentially expressed genes were identified; data not changes should favor adenoviral DNA replication.
The third period was from 24 to Our previous studies identified eighteen cellular genes, which all 36 hpi. At this time, the virus has taken over the control of the were up-regulated between 1 and 2 hpi Granberg et al. No dramatic changes in host gene expression occurred in artifact since up-regulation of gene expression is likely to be this interval. The fourth period was from 42 to 48 hpi when a easier to detect than down-regulation since the latter requires cytopathic effect appeared.
The number of differentially degradation of the mRNA to be detectable. Together, the results expressed genes increased significantly, the majority of which show that the response of the host cell to the incoming virus is were down-regulated. A conspicuous group consisted of genes very rapid.
Most of the genes in this category have functions that are involved in intra- and extra-cellular structure. Appar- linked to inhibition of cell growth. Consequently, growth ently, at this time point, the virus changes its strategy from suppression seems to be the first response to the incoming reproduction to efficient release and spread of the progeny virus.
Regulation of cellular gene expression during this period through destruction of the cell. It could be argued that this down- must be independent of adenoviral gene expression and is likely regulation was non-specific and the consequence of an imminent to be triggered by the attachment of the virus to cell surface cell death. However, this seems unlikely as a number of other receptors, the entry process of the virus, its intracellular transport genes were up-regulated in this period see Fig.
The second period specific, is well organized and takes place in steps. Nearly all of these discussed previously Zhao et al. Firstly, it is known cell immune response and regulates the expression of several that adenoviruses interfere with the pRb—E2F pathway.
This hundred target genes Ghosh et al. This suggests that the struggle regulation of a few genes were occasionally observed in this against cellular apoptosis is very complex. This might reflect the ongoing battle between the virus Regulation of the expression of cellular genes involved in and its host cell.
We straightforward. The expression of these genes Kim et al. It is likely that the E1B genes, together with other al. In addition, to its ability to bind hypophosphorylated pRb Missero et al. Apparently, regulation of TGF- the late phase of the infection Verrecchia et al. It is plausible differentially expressed. Wnts are powerful regulators of cell Different strategies for activation of the Wnt pathway proliferation and differentiation.
By 6 hpi, the expression of were used by these viruses. DDK1 encodes a secretory protein of the dickkopf the molecular mechanism behind the deregulation of Wnt family of inhibitors of Wnt-signaling.
An inhibitory effect on the signaling by adenovirus needs further study. Wnt pathway is likely to be another reflection of the cellular We have previously studied the host transcription profiles in antiviral response. One hundred and seventy-three cellular genes were 24 hpi, indicating that the suppression of the Wnt pathway was identified as differentially expressed. Here, expression of nearly blocked by adenovirus. Adenovirus seems to have additional genes was found to be regulated during the course of an stimulatory effects on Wnt signaling by down-regulating adenovirus infection in IMR cells.
Besides, a larger gene expression had begun. However, certain negative effectors array and a better labeling method was also used. The remaining blocks Wnt signaling Nelson and Nusse, Activation of genes were expressed in IMR cells, but 49 of them were Wnt signaling by different human tumor viruses has been unchanged during the infection. Additional studies encompassing bioinformatics, geno- HSPA1L and a gene without any known function clone ID mics, and proteomics are clearly called for.
The biological significance of the Cell culture, synchronization and cell phase analysis differences in the regulation of SMURF1 during an adenovirus infection in the two different cell lines was discussed earlier.
No single approach can fully unravel the essential amino acids, 1. After loading of the purified and pooled infected with Ad2 at a multiplicity of fluorescence-forming cDNA probes, hybridization was performed in a dark humid units FFU per cell Philipson, in serum-free medium. Mock-infected cells were collected at 6 hpi. Data handling and normalization were performed within the framework of LCB's Data warehouse.
For each experiment, intensity-dependent normalization was per- formed at print-tip level Yang et al. To identify differentially expressed genes across the time course, the normalized data were first exported and negatively flagged values excluded.
Western blot analysis of the expression of SMAD proteins. Using the same fold were harvested at 6 hpi M. Total cellular proteins were extracted. The datasets were combined and the individual Arany, Z. A family of transcriptional adaptor proteins targeted by the E1A oncoprotein. For visualization of the data, the Genesis Bannister, A. CBP-induced stimulation of c-Fos activity 1.
EMBO J. Bayley, S. Adenovirus E1A proteins and transformation Review. Bennett, E. The role of adenovirus E4orf4 protein in of the virus infection by monitoring the expression of E1A and viral replication and cell killing. Oncogene 20 54 , — Interaction of adenoviral E4 and E1b products in late gene expression.
Virology 2 , — For the Burgert, H. Nature , — Modulation of oncogenic transformation by the human tems. The list of primers and sequences is — Complex splicing patterns of RNAs from the early regions of adenovirus Corbin-Lickfett, K.
Adenovirus EkDa requires active proteasomes to promote late gene expression. Virology 1 , — Western blot analysis Coussens, L. Cell Physiol. Cuesta, R. Adenovirus-specific translation by Laemmli sample buffer After electrophor- Datto, M. The viral esis, the proteins were transferred to a polyvinylidene difluoride oncoprotein E1A blocks transforming growth factor beta-mediated membrane in a blotting chamber GE Healthcare.
Cell Biol. The membranes were Mummery, C. Adenovirus E1A incubated with the primary antibodies for 1 h at room antagonizes both negative and positive growth signals elicited by temperature.
Membranes were washed three times for 10 min transforming growth factor beta 1. Cell Growth Differ. Wild-type p53 mediates apoptosis by E1A, which is inhibited by E1B. Genes Dev. After 1 h of incubation at Deleu, L.
To detect signals on the membranes, an ECL Oncogene 20 57 , — Film Kodax was exposed and Duerksen-Hughes, P. Adenovirus E1A renders developed. Khalili, K. Association of human polyomavirus JCV with colon cancer: evidence for interaction of viral T-antigen and beta-catenin.
Cancer Acknowledgments Res. Farley, D. Activation of the early-late switch in adenovirus type 5 major late transcription unit expression by L4 We thank Catharina Svensson for valuable discussions, gene products. Ludmila Elfineh for excellent technical assistance and Aristidis Farrow, S. This work was supported Martinou, J.
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