Patent Grant
8811506
1. Technical Field
The present invention generally relates to a technical field of mobile communications, and more particularly to a base station apparatus, a user equipment (UE) terminal, and a communication control method in a mobile communication system using plural antennas.
2. Background Art
Research and development of a next-generation communication system have been continued at high speed. As the next-generation communication system of the W-CDMA (Wideband Code Division Multiple Access) system or the HSDPA (High Speed Downlink Packet Access) system, an LTE (Long Term Evolution) system has been studied by 3GPP (3rd Generation Partnership Project) which is a standards body of the W-CDMA. More specifically, in the LTE system as a radio access system, an OFDM (Orthogonal Frequency Division Multiplexing) scheme and an SC-FDMA (Single-Carrier Frequency Division Multiple Access) scheme have been studied to be applied to the downlink communications system and the uplink communications system, respectively (see, for example, Non-Patent Document 1).
The OFDM scheme is a multi-carrier system in which a frequency band is divided into plural sub-carriers having narrower frequency bands and data are mapped onto the sub-carriers so as to be transmitted. By using the orthogonality among the sub-carriers (i.e., independent from each other), the sub-carriers may partially overlap each other on the frequency axis, thereby enabling improving frequency use efficiency and achieving faster transmission rates.
The SC-FDMA scheme is a single-carrier type transmission system in which a frequency band is divided into plural narrower frequency bands so that the divided frequency bands are allocated to plural user equipment (UE) terminals (mobile stations) so that the user equipment (UE) terminals can transmit using different frequency bands, thereby reducing the interference between user equipment (UE) terminals. Further, in the SC-FDMA scheme, a range of the fluctuation of the transmission power may be made smaller; therefore, lower energy consumption of terminals may be achieved and a wider coverage area may also be obtained.
In both uplink transmissions and downlink transmissions of the LTE system, communications are carried out by allocating one or more physical channels shared among plural user equipment (UE) terminals. The channel shared among plural user equipment (UE) terminals is generally called a shared channel. In the LTE system, uplink communications and downlink communications are carried out by using a Physical Uplink Shared Channel (PUSCH) and a Physical Downlink Shared Channel (PDSCH), respectively.
In the communication system using such a shared channel as described above, it is required to perform signaling (a signaling process) to determine which shared channel is to be allocated to which user equipment (UE) terminal with respect to each sub-frame (having one (1) ms period in the LTE system). The control channel used for the signaling in the LTE system is called a Physical Downlink Control Channel (PDCCH) or a Downlink L1/L2 Control Channel (DL L1/L2 Control Channel). Further, data to be transmitted via the Physical Downlink Control Channel (PDCCH) includes, for example, Downlink Scheduling Information, Acknowledgement/Non-Acknowledgement Information (ACK/NACK), Uplink Scheduling Grant, an Overload Indicator, Transmission Power Control Command Bit and the like (see, for example, Non-Patent Document 2).
The Downlink Scheduling Information and the Uplink Scheduling Grant include information items to be used for the signaling determining which shared channel is to be allocated to which user equipment (UE) terminal. Further, the Downlink Scheduling Information may include information items regarding the Physical Downlink Shared Channel (PDSCH), such as allocation information of downlink Resource Blocks, an ID of a user equipment (UE) terminal (mobile station), the number of streams when MIMO (Multi-Input Multi-Output) communications are performed, information of Pre-coding Matrix, data size, modulation scheme, information of an HARQ (Hybrid Automatic Repeat reQuest) and the like. Further, the Uplink Scheduling Grant may include information items regarding the Physical Uplink Shared Channel (PUSCH), such as allocation information of uplink Resource Blocks, the ID of a user equipment (UE) terminal, the data size, the modulation scheme, uplink transmission power information, information of a Demodulation Reference Signal in an uplink MIMO and the like.
In a MIMO (Multi-Input Multi-Output) communication scheme, plural antennas are used to obtain faster data transmission rates and/or higher quality of the communications. Further, in the MIMO communication scheme, a transmission signal is copied and each of the signals is combined with an appropriate weighting coefficient and transmitted. By doing this, it becomes possible to transmit the signals as controlled beams having directionality. This method is called a Pre-coding method and the weighting factor (or weighting) used in this method is called a Pre-coding matrix.
To appropriately demodulate a shared data channel (shared channel) to which the Pre-coding is applied, it is required to accurately perform channel compensation for the shared data channel. In one method to correctly perform the channel compensation, a reference signal is provided to which a Pre-coding is applied in addition to the shared data channel to which the Pre-coding is applied. Probably, if such reference signal is provided, the channel estimation may be accurately performed. However, not a small number of resources are required to be provided to transmit the reference signal, which may increase the overhead. Therefore, from the viewpoint of improving the throughput across the system, this method may not be preferable.
To overcome the problem, it may be thought that there is provided a Common Reference Signal which is common to all the user equipment (UE) terminals so that the channel compensation be performed based on the Common Reference Signal. When this method is used, it is required that a data indicating which Pre-coding (matrix) is to be applied (used) to the shared data channel is transmitted to the user equipment (UE) terminal. In the following, for explanatory purposes, the data are called Pre-coding Matrix Indicator (PMI).
According to an embodiment of the present invention, there may be provided a MIMO mobile communication system in which downlink overhead can be reduced and effective use of radio resources can be achieved.
According to an aspect of the present invention, there is provided a base station apparatus capable of communicating with a user equipment terminal in a multi-input multi-output (MIMO) mobile communication system using Pre-coding. The base station apparatus includes a receiving unit receiving a Pre-coding Matrix Indicator (PMI) indicating a specific Pre-coding matrix, a determination unit determining a value of a flag indicator indicating whether the Pre-coding matrix specified in the PMI is to be used for downlink communications, a control signal generation unit generating a downlink control signal including at least the flag indicator, and a transmission unit transmitting a signal including the downlink control signal in downlink.
According to an embodiment of the present invention, there may be provided a MIMO mobile communication system in which downlink overhead can be reduced and effective use of radio resources can be achieved.
However, there may a case where the Pre-coding matrix used in the downlink communications by the base station apparatus eNB is different from the Pre-coding matrix determined by the user equipment (UE) terminal based on the received flag indicator from the base station apparatus eNB. This problem may occur when, for example, the base station apparatus eNB fails to receive a correct PMI and recognizes a wrong PMI; and as a result, a wrong Pre-coding matrix indicated by the wrong PMI is used as the Pre-coding matrix for the downlink transmissions, when the user equipment (UE) terminal fails to received a correct flag indicator and recognizes a wrong flag indicator or the like. In such cases, if the user equipment (UE) terminal performs a weighting process and the following processes on the received signal from the base station apparatus eNB using the Pre-coding matrix provided by the user equipment (UE) terminal, remarkably deteriorated signals may be wastefully derived (obtained). To avoid this problem, preferably, the user equipment (UE) terminal may determine whether a data transmitted from the base station apparatus eNB is correct.
According to an embodiment of the present invention, the base station apparatus eNB performs a channel-coding (coding) process by treating a data part as a unit of the coding, the data part including control bits, the flag indicator (bit(s)), and error detection bits. The error detection bits are derived (calculated) by performing a predetermined calculation on a calculation target including at least the control bits and the flag indicator (bit(s)). Further, when the flag indicator (bit(s)) is a predetermined value, the PMI is included in the calculation target; and on the other hand, when the flag indicator (bit(s)) is another predetermined value, the PMI is not included in the calculation target. On the other hand, the user equipment (UE) terminal also derives (calculates) the error detection bits by performing the predetermined calculation on the calculation target including the control bits, the flag indicator (bit(s)), and when necessary, the PMI. Then, the error detection bits provided (calculated) by the base station apparatus eNB are compared with the error detection bits provided (calculated) by the user equipment (UE) terminal. By doing this, it may become possible to determine whether the Pre-coding matrix provided by the user equipment (UE) terminal based on the flag indicator is actually being used in the downlink communications.
The number of bits of the flag indicator is less than that of the PMI; therefore, it may not be easy to obtain a sufficiently high error correction capability if only the flag indicator (bit(s)) is included in the calculation target for obtaining (calculating) the error detection bits. To avoid such problem, as described above, according to an embodiment of the present invention, not only the flag indicator (bit(s)) but also the control bits and the error detection bits are collectively coded. By doing this, it may become possible to obtain a larger coding gain when compared with a case where only the flag indicator (bit(s)) is coded.
The number of bits of the flag indicator is not limited to a specific number, but may be (1) as the minimum number. When the Pre-coding matrix specified in the PMI is not to be used for the downlink communications, the default Pre-coding matrix already known to both the base station apparatus eNB and the user equipment (UE) terminal may be used as the Pre-coding matrix to be used for the downlink communications. When determining this, the default Pre-coding matrix is always used for the downlink communications when the Pre-coding matrix specified in the PMI is not actually used. Therefore, by checking the value of the flag indicator (bit(s)) having a smaller number of bits than that of the PMI, it may become possible to specify the Pre-coding matrix that is actually used for the downlink communications.
In a case where the value of the flag indicator (bit(s)) indicates that the default Pre-coding matrix is not used for the downlink transmission (hereinafter this case may be referred to a case when “X=0”), a data part including a data in which the PMI is convolved with the control bits, the flag indicator (bit(s)), and the error detection bits may be coded (channel-coded) and transmitted to the user equipment (UE) terminal. This may be preferable from the viewpoint of transmitting the PMI to the user equipment (UE) terminal without increasing the number of the control bits. However, in this case, it is required to separately transmit data indicating the number of bits occupied (convolved) with the PMI to the user equipment (UE) terminal.
According to an embodiment of the present invention, the base station apparatus eNB may perform an error detection process on the PMI which is feedback from the user equipment (UE) terminal (hereinafter may be referred to as “feedback PMI”). This process may be preferable from the viewpoint of reliably determining whether the default Pre-coding matrix is to be used for the downlink communications. Further, for example, the user equipment (UE) terminal receives both the PMI and the error detection bits of the PMI and performs an error detection process on the PMI based on a comparison between the error detection bits calculated by the user equipment (UE) terminal and the error detection bits calculated by the base station apparatus eNB. Further, the base station apparatus eNB may perform the error detection process based on a received quality level of an uplink reference signal received from the user equipment (UE) terminal. Further, the base station apparatus eNB may perform the error detection process based on likelihood data of a shared data channel received from the user equipment (UE) terminal.
In the following, an embodiment of the present invention is described with reference to the accompanying drawings. In the embodiment, some specific values may be used as examples. Such values, however, are for explanatory purposes only and, unless otherwise described, any other appropriate value may be used.
Embodiment 1
Operations Before Downlink Communication is Started
In the following, the operations of the base station apparatus eNB and the user equipment (UE) terminal in a mobile communication system according to an embodiment of the present invention is described. In the mobile communication system, it is assumed that while Pre-coding is performed, communications based on a MIMO (Multi-Input Multi-Output) scheme are performed. Therefore, both the base station apparatus eNB and the user equipment (UE) terminal have plural transmission/receiving antennas and weightings based on Pre-coding matrices are applied so that signals are transmitted in the appropriate directions from the antennas.
Next, in step S504, the user equipment (UE) terminal transmits the determined PMI to the base station apparatus eNB.
Next, the process goes to step S602 shown in
In step S604, the base station apparatus eNB determines the Pre-coding matrix specified in the PMI and further determines whether the Pre-coding matrix specified in the PMI is suitable to be used for the downlink communications. In this case, the base station apparatus eNB may determine whether the Pre-coding matrix is suitable based on the number of streams, the number of transmission antennas, an amount of downlink traffic or the like. In this embodiment, when determining that the Pre-coding matrix specified in the PMI is not suitable to be used for the downlink communications, a default Pre-coding matrix already known to both the base station apparatus eNB and the user equipment (UE) terminal is selected as the Pre-coding matrix to be used for the downlink communications. More than one default Pre-coding matrix may be provided; however, for simplification purposes, herein it is assumed that there is provided only one default Pre-coding matrix. Namely, in this embodiment, there are two choices provided for selecting the Pre-coding matrix; i.e., one choice is to select the Pre-coding matrix specified in the PMI, and the other choice is to select the default Pre-coding matrix. Further, in this embodiment, the flag indicator is defined using one (1) bit to determine which of the Pre-coding matrices is to be selected as the Pre-coding matrix to be used for the downlink communications. Therefore, in this case, depending on the value of the flag indicator bit (for example, whether the value is “1” or “0”), the default Pre-coding matrix or the Pre-coding matrix specified in the PMI is selected to be used. When more than one default Pre-coding matrix are provided, more than one flag indicator bits may be used to express the necessary number of values of the flag indicator. In this case, for example, when three (3) types of default Pre-coding matrices are provided, two (2) bits of flag indicator may be used to transmit data indicating which type of the Pre-coding matrix is to be used for the downlink communications.
In step S604, when determining that the default Pre-coding matrix is selected as the Pre-coding matrix to be used for downlink communications, the process goes to step S606. In step S606, the error rate bits are calculated assuming that the default Pre-coding matrix is to be used for downlink communications.
Next, in step S608 of
On the other hand, in step S604, when determining that the Pre-coding matrix specified in the PMI is selected as the Pre-coding matrix to be used for downlink communications, the process goes to step S610. In step S610, the error rate bits are calculated assuming that the Pre-coding matrix specified in the PMI is to be used for downlink communications.
Next, in step S612 of
In this step S612, as shown in
In step S614 of
Further, in step S602, the base station apparatus eNB may further determine whether the received feedback PMI is correct. In this case, for example, in receiving not only the feedback PMI but also error detection bits of the feedback PMI from the user equipment (UE) terminal, the base station apparatus eNB may determine whether the received feedback PMI is correct based on the received error detection bits. Further, the base station apparatus eNB may determine whether the received feedback PMI is correct based on received quality information (e.g. received SINR) of a received uplink reference signal from the user equipment (UE) terminal. Further, upon receiving an uplink shared channel (UL-SCH), the base station apparatus eNB may determine whether the received feedback PMI is correct based on likelihood data obtained as a decoding result of the received uplink shared channel (UL-SCH). Further, the base station apparatus eNB may determine whether the received feedback PMI is correct based on likelihood data obtained as a decoding result of the received feedback PMI itself. These methods may be used separately or in combination thereof.
Further, as shown in
Operations after Downlink Communication is Started
Referring back to
Next, in step S508, the data bits (data part) received in the Physical Downlink Shared Channel (PDSCH) (received signal) in step S506 are decoded (channel-decoded). As described in step S608 and S610 of
In step S510, the error detection bits when X=1 are calculated. When the process goes to this step S510, it is in a case where the default Pre-coding matrix is selected as the Pre-coding matrix to be used for the downlink communications. Therefore, in the base station apparatus eNB, the error detection bits are derived (calculated) in step S606 of
On the other hand, in step S512, the error detection bits when X=0 is calculated. When the process goes to this step S512, it is in a case where the Pre-coding matrix specified in the PMI is selected as the Pre-coding matrix to be used for the downlink communications. Therefore, in the base station apparatus eNB, the error detection bits are derived (calculated) in step S610 of
Next, in step S514, the user equipment (UE) terminal compares the error detection bits derived (calculated) in the base station apparatus eNB with the error detection bits derived (calculated) in the user equipment (UE) terminal for error detection. In the error detection comparison, when determining that the error detection bits derived (calculated) in the base station apparatus eNB are equal to the error detection bits derived (calculated) in the user equipment (UE) terminal, the user equipment (UE) terminal may correctly determine that the Pre-coding matrix used for the downlink communications is the default Pre-coding matrix or the Pre-coding matrix specified in the PMI.
Next, in step S516, based on the correct Pre-coding matrix confirmed in step S514, the channel compensation and the demodulation of the Physical Downlink Shared Channel (PDSCH) may be accurately performed.
According to this embodiment of the present invention, when the base station apparatus eNB fails to receive a correct PMI or when the user equipment (UE) terminal fails to receive correct data (signal) from the base station apparatus eNB, the user equipment terminal may obtain a negative result in the error detection comparison process (in step S514). Based on the result of the error detection comparison, the user equipment (UE) terminal may immediately discard the received data regarding the incorrect Pre-coding matrix or keep the received data having a lower likelihood level for preparing the following packet combining. According to this embodiment of the present invention, it may become possible to detect a difference of recognition concerning the Pre-coding matrix to be used for the downlink communication between the base station apparatus eNB and the user equipment (UE) terminal.
Configuration of Base Station Apparatus eNB
The RF receiver section 102 performs signal processing so as to convert the signals received by plural antennas #1 through #M into baseband digital signals. The signal processing may include, for example, power amplification, band-limiting, analog-to-digital conversion and the like.
The uplink receiving signal demodulating section 104 adequately separates received signals transmitted in uplink communications, the signals including a Physical Uplink Shared Channel (PUSCH), control channel (such as the L1/L2 control channel (L1/L2 CCH)), a reference signal and the like. Further, the uplink receiving signal demodulating section 104 performs channel estimation, received signal quality measurement and the like. As the received signal quality measurement, for example, SINR (Signal-to-Interference and Noise power Ratio) measurement may be performed.
The data signal decoding section 106 separates a received signal transmitted through transmission antennas into one or more streams and decodes each stream. The decoding is performed corresponding to the coding performed in the transmitting side. In the decoding, the likelihood data are obtained and the error correction is performed.
The control bits decoding section 108 decodes the control channel and extracts the data included in the L1/L2 control channel (L1/L2 CCH). According to an embodiment of the present invention, the control bits decoding section 108 extracts the PMI and specifies the Pre-coding matrix transmitted from the user equipment (UE) terminal. When receiving not only the PMI (feedback PMI) but also the error detection bits (typically CRC error detection bits) of the PMI, the control bits decoding section 108 may perform an error detection process on the PMI and output a result of the error detection.
The PMI validity determination section 110 determines whether the PMI feedback from the user equipment (UE) terminal (i.e., feedback PMI) is correct. To that end, when receiving not only the PMI (feedback PMI) but also the error detection bits of the PMI, the PMI validity determination section 110 may determine whether the feedback PMI is correct by using the error detection bits. Further, the PMI validity determination section 110 may determine whether the feedback PMI is correct based on the received quality information (e.g. received SINR) of the received uplink reference signal from the user equipment (UE) terminal. Further, the PMI validity determination section 110 may determine whether the feedback PMI is correct based on the likelihood data obtained when the received uplink shared channel (UL-SCH) is decoded. Further, the PMI validity determination section 110 may determine whether the feedback PMI is correct based on the likelihood data obtained as a decoding result of the received feedback PMI itself.
The Pre-coding matrix selecting section 112 selects (determines) the Pre-coding matrix to be used for the downlink communications based on the determination result of the PMI validity determination section 110 and a predetermined criterion (item) such as the necessary number of streams for downlink communications, the number of transmission antennas, an amount of downlink traffic or the like. For example, when the feedback PMI is correctly received, the Pre-coding matrix specified in the PMI may be used as the Pre-coding matrix to be used for the downlink communications. On the other hand, if the feedback PMI is incorrectly received, the use of the Pre-coding matrix specified in the PMI may become impractical. In this case, the default Pre-coding matrix already known to both the base station apparatus eNB and the user equipment (UE) terminal may be used. Further, even when the feedback PMI is correctly received, based on the actually required amount of downlink traffic, any Pre-coding matrix other than that specified in the PMI may be used. Further, the Pre-coding matrix selecting section 112 provides (generates) the flag indicator indicating, for example, whether the Pre-coding matrix specified in the PMI (feedback PMI) is selected as the Pre-coding matrix to be used for downlink communications (X=0) or the default Pre-coding matrix is selected as the Pre-coding matrix to be used for the downlink communications (X=1) and transmits the generated flag indicator to the error detection bit addition section 114. When X=0, the feedback PMI is also transmitted to the error detection bit addition section 114.
The error detection bit addition section 114 derives (calculates) the error detection bits (typically CRC error detection bits) by performing a predetermined calculation on the data bits (data part) including the control bits (control data), the flag indicator bit (e.g., indicating a value of “0” or “1”), and, when necessary, the feedback PMI.
The PMI removing section 116 removes the feedback PMI when the feedback PMI is included in the calculation target used for deriving (calculating) the error detection bits and, regardless of the value of the flag indicator, provides the data part including control bits, the flag indicator (bit(s)), and error detection bits.
The channel-coding section 118 performs the channel coding process by treating the data part as a unit of the channel-coding (coding) to generate a channel-coded signal.
The control bits modulation section 120 performs the data modulation on the channel-coded signal.
The serial-parallel conversion section 122 converts a serial transmission signal to be transmitted by using the Physical Downlink Shared Channel (PDSCH) into plural parallel streams.
The channel-coding section 124 performs the channel-coding process on each of the streams to generate channel-coded streams.
The data modulation section 126 performs the data modulation on the channel-coded streams.
The Pre-coding matrix multiplying section 128 performs the weighting based on the Pre-coding matrix on each of the streams, the Pre-coding matrix being selected (determined) by the Pre-coding matrix selecting section 112.
The signal multiplexing section 130 multiplexes the control channel, the Physical Downlink Shared Channel (PDSCH), and other channels.
The IFFT section 132 performs the inverse fast Fourier transform on each of the multiplexed streams for OFDM modulation.
The RF transmitter section 134 performs processes for wirelessly transmitting the streams using plural transmission antennas. The processes may include the addition of guard intervals, the digital-to-analog conversion, the band-limiting, the power amplification and the like.
Configuration of User Equipment (UE) Terminal
The data signal coding and modulation section 202 performs channel-coding and data modulation on the Physical Uplink Shared Channel (PUSCH).
The control signal coding and modulation section 204 performs channel-coding and data modulation on an Uplink L1/L2 Control Channel (UL L1/L2 Control Channel).
The uplink transmission signal generation section 206 adequately performs mapping of the control channel and the shared channel to provide (output) transmission streams. In this case, for example, some processes such as a DFT (Discrete Fourier Transform) process, a mapping process in frequency domain, and the IFFT process are performed on each of the streams.
The RF transmitter section 208 performs processes of converting the streams (in baseband) into a signal to be wirelessly transmitted using plural transmission antennas. The processes may include digital-to-analog conversion, band-limiting, power amplification and the like.
The RF receiver section 210, contrary to the RF transmitter section 208, performs processes of converting the signals wirelessly received by plural receiving antennas into streams in baseband. The processes may include power amplification, band-limiting, analog-to-digital conversion and the like with respect to each of the stream.
The FFT section 212 performs the fast Fourier transform on each of the stream for OFDM demodulation.
The Pre-coding matrix selecting section 214 selects the Pre-coding matrix suitable for the downlink communications based on the received quality level of the reference signal in the received signal from the base station apparatus eNB and outputs the PMI indicating the selected Pre-coding matrix. Typically, the Pre-coding matrix is one of the predetermined number of Pre-coding matrices (U1, U2, . . . , UP). Namely, the PMI specifies the Pre-coding matrix (Ui) of the Pre-coding matrices (U1, U2, . . . , UP). More generally, the Pre-coding matrices are not a group of choices and may be adaptively adjustable to so that any appropriate Pre-coding matrix can be formed.
The PMI accumulation section 216 stores the PMI for a certain period, the PMI being determined by the Pre-coding matrix selecting section 214.
The data demodulation section 218 demodulates the data part in the received signal.
The channel decoding section 220 performs the channel-decoding (decoding) process by treating the data part as a unit of the channel-decoding, the data part including the control bits, the flag indicator (bit(s)), and error detection bits (typically CRC detection bits). The unit of the channel-decoding corresponds to the unit of the coding performed in the transmitting side. As a result of the channel-decoding (decoding), the value of “X” of the flag indicator is determined.
When the value of the flag indicator is a predetermined value (in the above example, when X=0), from the PMI accumulation section 216, the PMI adding section 222 extracts the PMI for the calculation of the error detection bits, the PMI being transmitted to the base station apparatus eNB before. In this case, the error detection bits (typically CRC error detection bits) may be derived (calculated) by performing a predetermined calculation on the data bits (data part) including the control bits (control data), the flag indicator bit (indicating a value of “0”), and the provided PMI. On the other hand, when the value of the flag indicator has another value (in the above case, X=1), the error detection bits are derived (calculated) without providing (using) any PMI. Namely, the error detection bits (typically CRC error detection bits) may be derived (calculated) by performing the predetermined calculation on the data bits (data part) including the control bits (control data) and the flag indicator bit (indicating a value of “1”).
The error detection section 224 compares the error detection bits provided (calculated) in the base station apparatus eNB with the error detection bits provided (calculated) by the user equipment (UE) terminal (PMI adding section 222) to determine whether data transmitted from the base station apparatus eNB are correct (whether any error is detected). When no error is detected, the following processes may be performed based on the data from the base station apparatus eNB. On the other hand, when an error is detected, the data from the base station apparatus eNB may be discarded or kept for preparing the following packet combining.
The Pre-coding matrix multiplying section 230 performs the weighting process using the Pre-coding matrix on the received Physical Downlink Shared Channel (PDSCH). This Pre-coding matrix may be the Pre-coding matrix previously feedback from the user equipment (UE) terminal to the base station apparatus eNB or the Pre-coding matrix determined as the default Pre-coding matrix, which depends on a result of the determination of the error detection section 224.
The signal separation section 232 separates the received signal into streams using any of the signal separation algorithms already known in the art.
The channel decoding section 234 performs the channel-decoding (decoding) on the received Physical Downlink Shared Channel (PDSCH).
The parallel-serial conversion section 236 converts plural parallel streams into a serial signal sequence and outputs the converted signal sequence which is equal to the signal sequence provided in the base station apparatus eNB before being wirelessly transmitted.
The present invention is described above by referring to a specific embodiment. However, a person skilled in the art may understand that the above embodiments are described for illustrative purpose only and may think of examples of various modifications, transformations, alterations, changes and the like. To promote an understanding of the present invention, the specific values are used as examples throughout the description. However, it should be noted that such specific values are just sample values unless otherwise described, and any other values may be used. For illustrative purposes, the apparatus according to an embodiment of the present invention is described with reference to the functional block diagram. However, such an apparatus may be provided by hardware, software, or a combination thereof. The present invention is not limited to the embodiments described above and various modifications, transformations, alteration, exchanges and the like may be made without departing from the scope and spirit of the present invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2007-161942 | Jun 2007 | JP | national |
The present application is a continuation of U.S. application Ser. No. 12/663,980 filed on Dec. 10, 2009, which is a national phase application of international application number PCT/JP2008/061005, filed Jun. 16, 2008, and claims priority to Japanese Patent Application No. 2007-161942 filed on Jun. 19, 2007, the entire contents of which are hereby incorporated by reference.
| Number | Name | Date | Kind |
|---|---|---|---|
| 7277475 | Nguyen et al. | Oct 2007 | B1 |
| 7629902 | Zhang et al. | Dec 2009 | B2 |
| 7729442 | Kim et al. | Jun 2010 | B2 |
| 7898948 | DiGirolamo et al. | Mar 2011 | B2 |
| 8155070 | Lee et al. | Apr 2012 | B2 |
| 8311489 | Alexiou et al. | Nov 2012 | B2 |
| 8325788 | Khan | Dec 2012 | B2 |
| 8572461 | Pan | Oct 2013 | B2 |
| 20060209980 | Kim et al. | Sep 2006 | A1 |
| 20060276212 | Sampath et al. | Dec 2006 | A1 |
| 20080260059 | Pan | Oct 2008 | A1 |
| 20080303699 | Zhang et al. | Dec 2008 | A1 |
| 20090002235 | Ito | Jan 2009 | A1 |
| 20090006925 | Pan | Jan 2009 | A1 |
| 20110280342 | Kim et al. | Nov 2011 | A1 |
| 20120257592 | Taoka et al. | Oct 2012 | A1 |
| 20120275536 | Khojastepour et al. | Nov 2012 | A1 |
| 20140038660 | Malladi et al. | Feb 2014 | A1 |
| 20140092850 | Ko et al. | Apr 2014 | A1 |
| Number | Date | Country |
|---|---|---|
| 2010-525684 | Jul 2010 | JP |
| 2006-0096360 | Sep 2006 | KR |
| 2006098111 | Sep 2006 | WO |
| 2008131352 | Oct 2008 | WO |
| Entry |
|---|
| Extended European Search Report issued in corresponding European Application No. 08777243.0 mailed Jul. 4, 2013 (8 pages). |
| Huawei; “DL control signaling of MIMO PMI information for SU-MIMO”; 3GPP TSG RAN WG1 #49, R1-072318; Kobe, Japan; May 7-11, 2007 (5 pages). |
| International Search Report w/translation from PCT/JP2008/061005 dated Aug. 19, 2008 (4 pages). |
| Written Opinion from PCT/JP2008/061005 dated Aug. 19, 2008 (3 pages). |
| Motorola, “PMI Downlink Signaling and PDCCH Format”; 3GPP TSG RAN1#50bis, R1-074001; Shanghai, China; Oct. 8-12, 2007 (2 pages). |
| ZTE, “Considerations on DL Signaling for Support of SU- and MU-MIMO”; 3GPP TSG-RAN WG1 #50bis, R1-074225; Shanghai, China; Oct. 8-12, 2007 (3 pages). |
| NEC Group, “Downlink Control channels: formats and contents”; TSG-RAN WG1#52, R1-081016; Sorrento, Italy; Feb. 11-15, 2008 (6 pages). |
| Discussion moderator (Ericsson), “Notes from of discussions on PDCCH contents”; TSG-RAN WG1 #50, R1-073870; Athens, Greece; Aug. 20-24, 2007 (3 pages). |
| 3GPP TR 25.814, V7.0.0; “3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Physical layer aspects for evolved Universal Terrestrial Radio Access (UTRA)(Release 7)”; Jun. 2006 (126 pages). |
| NTT Docomo, et al., “Downlink L1/L2 Control Signaling Channel Structure: Coding”; 3GPP TSG RAN WG Meeting #47bis, R1-070103; Sorrento, Italy; Jan. 15-19, 2007 (17 pages). |
| Office Action in Japanese Patent Application No. 2007-161942 mailed Oct. 5, 2010, with partial English translation thereof (4 pages). |
| Korean Office Action for Application No. 10-2009-7025964, mailed on Feb. 27, 2014 (9 pages). |
| esp@cenet Patent Abstract for Korean Publication No. 2006-0096360, publication date Sep. 11, 2006 (1 page). |
| Korean Patent Abstract for Korean Publication No. 2006-0096360, publication date Sep. 11, 2006 (1 page). |
| Number | Date | Country | |
|---|---|---|---|
| 20130163545 A1 | Jun 2013 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 12663980 | US | |
| Child | 13767411 | US |
