USOO784.8439B2
`
`(12) United States Patent
`She et al.
`
`(10) Patent No.:
`(45) Date of Patent:
`
`US 7,848,439 B2
`Dec. 7, 2010
`
`(54) COMMUNICATION APPARATUS,
`COMMUNICATION SYSTEM, AND
`COMMUNICATION METHOD
`
`(75) Inventors: Xiaoming She, Beijing (CN); Jifeng Li,
`Kanagawa (JP)
`(73) Assignee: Panasonic Corporation, Osaka (JP)
`(*) Notice:
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 769 days.
`11/719,611
`
`(21) Appl. No.:
`
`(22) PCT Filed:
`(86). PCT No.:
`
`Nov. 18, 2005
`PCT/UP2005/021246
`
`S371 (c)(1),
`(2), (4) Date: May 17, 2007
`(87) PCT Pub. No.: WO2006/054697
`PCT Pub. Date: May 26, 2006
`
`(65)
`
`Prior Publication Data
`US 2009/O14786.6 A1
`Jun. 11, 2009
`
`Foreign Application Priority Data
`(30)
`Nov. 19, 2004 (CN) ........................ 2004. 1 OO94967
`
`(51) Int. Cl.
`(2006.01)
`H04K L/10
`(52) U.S. Cl. ....................... 375/260; 375/267; 375/299;
`375/324; 375/349
`(58) Field of Classification Search ................. 375/260,
`375/267,299, 324, 349
`See application file for complete search history.
`References Cited
`
`(56)
`
`U.S. PATENT DOCUMENTS
`
`6,836,484 B2 12/2004 Suzuki
`7,505,529 B2 * 3/2009 Kwak et al. ................. 375,295
`2003/0231706 A1 12/2003 Hwang
`2006/0008020 A1* 1/2006 Blankenship et al. ....... 375,261
`
`FOREIGN PATENT DOCUMENTS
`
`CN
`CN
`CN
`JP
`
`1466.297
`1469662
`14966.23
`O1238269
`
`1, 2004
`1, 2004
`5, 2004
`8, 2001
`
`(Continued)
`OTHER PUBLICATIONS
`
`PCT International Search Report dated Feb. 14, 2006.
`(Continued)
`Primary Examiner Shuwang Liu
`Assistant Examiner Kabir A Timory
`(74) Attorney, Agent, or Firm—Dickinson Wright PLLC
`
`(57)
`
`ABSTRACT
`
`A communication apparatus capable of improving the spec
`trum usage rate of a system, especially, the spectrum usage
`rate in connection with both a fast fading and a channel
`estimation error as compared with the conventional Sub-band
`adaptive method, while reducing the degree of the difficulty
`in achieving the adaptation, and further reducing the feedback
`overhead. In this apparatus, a Sub-band group AMC param
`eter selecting part (318) selects an AMC parameter of each
`sub-band. An adaptive reception control part (503) must con
`trol an adaptive demodulating/decoding part (311), while
`controlling a parallel/serial converter (312) in a stage preced
`ing the adaptive demodulation and decoding processes, and
`combining received symbols in the same Sub-band group for
`demodulation and decoding.
`
`6.351,499 B1* 2/2002 Paulraj et al. ............... 375,267
`
`11 Claims, 16 Drawing Sheets
`
`
`
`
`
`306
`
`ADAPTIVE TRANSMISSION
`CONTRO
`
`
`
`PARAMETER
`RECEPTIONA
`EXTRACTION
`
`x DATA
`
`ADAPTIVE
`MODUATING
`AND COOING
`
`NERVAL
`INSERTION
`
`
`
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`US 7,848.439 B2
`Page 2
`
`JP
`JP
`WO
`WO
`
`FOREIGN PATENT DOCUMENTS
`O3169.036
`6, 2003
`2004 104293
`4/2004
`2004040813
`3, 2004
`2004040827
`3, 2004
`OTHER PUBLICATIONS
`
`Conference, 2003, VTC 2003-Fall, 2003 IEEE 58th, Aug. 9, 2003,
`pp. 1895-1899.
`
`Yuanrun Teng, et al.; "Grouping Adaptive Modulation Method for
`Burst Mode OFDM Transmission System.” Technical Report of
`IEICE, Aug. 31, 2003, vol. 101, No. 280, pp. 51-57.
`
`Sharath B. Reddy, et al., “An Efficient Blind Modulation Detection
`Algorithm for Adaptive OFDM Systems.” Vehicular Technology
`
`* cited by examiner
`
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`U.S. Patent
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`Dec. 7, 2010
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`U.S. Patent
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`US 7,848.439 B2
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`US 7,848.439 B2
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`U.S. Patent
`
`Dec. 7, 2010
`
`Sheet 11 of 16
`
`US 7,848.439 B2
`
`TRANSMISSION SIDE
`
`RECEIVING SIDE
`901
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`CHANNEL ESTIMATION
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`902
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`ADAPTIVE PARAMETER
`SELECTION FOR EACH
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`U.S. Patent
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`US 7,848.439 B2
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`Dec. 7, 2010
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`Dec. 7, 2010
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`US 7,848,439 B2
`
`1.
`COMMUNICATION APPARATUS,
`COMMUNICATION SYSTEM, AND
`COMMUNICATION METHOD
`
`TECHNICAL FIELD
`
`The present invention relates to a communication appara
`tus, communication system, and communication method, and
`particularly relates to a communication apparatus, communi
`cation system and communication method carrying out adap
`tive modulation and coding in adaptive transmission technol
`ogy in Subcarrier communication systems—that is, in
`wireless communication orthogonal frequency division mul
`tiplexing (OFDM) system.
`
`BACKGROUND ART
`
`10
`
`15
`
`2
`adaptivity in this case refers to adaptivity at two domains of
`time domain and frequency domain. Currently, as an adaptive
`configuration, AMC in OFDM is divided into two, AMC
`based on subcarriers and AMC based on Subbands. The AMC
`based on subcarriers referred to here refers to carrying out
`transmission using a modulation method and a coding
`method that are different per OFDM subcarrier taking each
`subcarrier as a minimum unit of adaptivity. However, AMC
`based on subcarriers is very difficult to be implemented, and,
`in addition, has the problem that feedback overhead is too
`large. Typically, it is difficult to implement an AMC method
`based on Subcarriers in an actual system. As another adaptive
`configuration in OFDM, a Subband configuration using inde
`pendent coding, namely, a Subband adaptive method of the
`related art is, relatively, typically used.
`FIG. 2 shows subband adaptive modulation and coding of
`the related art.
`In this configuration, all of the subcarriers on the OFDM
`frequency domain are divided into several Subbands. Here, a
`Subband indicates a Subcarrier group comprised of Subcarri
`ers in neighboring positions on the frequency domain. For
`example, in FIG. 2, the total number of Subbands is N. One
`modulation coding block is then formed by the same Sub
`bands at several (in the case of FIG.2, M) neighboring OFDM
`symbols. In subband adaptivity of the related art of FIG. 2, the
`modulation coding blocks carry out estimation of coding
`modulation parameters based on the channel characteristics
`and carry out independent coding. The numbers within the
`coding modulation blocks of FIG. 2 denote the classification
`coding modulation parameters of encoded modulation blocks
`belong to.
`Typically, coding modulation parameters corresponding to
`classifications for the coding modulation parameters are
`decided in initial stages of a system. For example, the rela
`tionships between a classification, coding parameter, and
`modulation parameter are shown in Table 1 as an example.
`The present invention is by no means limited to Table 1.
`
`TABLE 1
`
`Classification
`
`Coding parameter
`
`Modulation parameter
`
`O
`1
`2
`3
`4
`5
`6
`
`Not transmitted
`/3Turbo
`/3Turbo
`*/ATurbo
`2/Turbo
`3/ATurbo
`2/Turbo
`
`Not transmitted
`BPSK
`QPSK
`QPSK
`8PSK
`16QAM
`64QAM
`
`Next, a block view implementing a subband adaptive
`method of the related art is shown in OFDM in FIG. 3.
`FIG. 3A and FIG. 3B are block views showing an OFDM
`AMC system combining OFDM and AMC of the related art.
`When communication between a communication appara
`tus of FIG. 3A (transmission side) and communication appa
`ratus of FIG. 3B (receiving side) is assumed to be carried out,
`typical examples are given by a base station (AP) of FIG. 3A
`and a mobile terminal (UE) of FIG. 3B. Further, assume that
`an AMC mechanism is used in transmission from FIG. 3A to
`FIG. 3B.
`On the transmission side of FIG.3A, information bits to be
`transmitted first pass through adaptive modulation/coding
`section 301. The output serial modulation symbols then pass
`through serial/parallel converter (S/P) 302 and inverse fast
`Fourier transformer (IFFT) 303 so that symbols in the fre
`quency band are converted to the time domain. The symbols
`then pass through parallel/serial converter (P/S)304 and have
`
`25
`
`35
`
`40
`
`45
`
`OFDM technology is mainstream technology for imple
`menting high-speed wireless data transmission. OFDM tech
`nology theory is transmitting high-speed data using a large
`number of Subcarriers that are orthogonal, and data rates of
`the subcarriers are relatively low. Compared to a typical fre
`quency division multiplexing system, orthogonality of a Sub
`carrier in OFDM improves spectral efficiency of the system.
`In OFDM, the whole signal bandwidth is divided into a plu
`rality of narrow subcarrier frequency bandwidths, and flat
`fading occurs when the subcarrier bandwidths are smaller
`than the channel bandwidth. In this way, compared to the
`monocarrier system, flat fading in OFDM can be imple
`mented in a more straightforward manner. Currently, OFDM
`30
`technology is successfully applied to asynchronous digital
`subscriberlines (ADSL), digital television broadcasts (DVB)
`and wireless ATM (WATM) systems.
`In order to improve a spectrum utilization rate in wireless
`systems, adaptive and high spectrum utilization rate-trans
`mission technology has been requested for high-speed wire
`less data transmission for fading channels. In fading chan
`nels, compared to fixed coding modulation, adaptive
`modulation/coding technology is capable of effectively
`improving a throughput and an error rate (BER) of a system.
`Here, the throughput referred to is the spectrum utilization
`rate of the system—that is, the amount of information trans
`mitted within a unit spectrum bandwidth and a unit time. The
`basic concept of AMC technology is adaptively changing one
`or more types of transmission power, symbol transmission
`rate, coordinate size, coding rate and coding mechanism
`based on channel characteristics at the current point and,
`when channel conditions are good, transmitting a large
`amount of information to increase spectrum utilization rate,
`and, when channel conditions are poor, transmitting a small
`50
`amount of information to ensure a certain receiving BER
`request.
`Before introducing an AMC method in OFDM, first, chan
`nel characteristics in OFDM transmission will be introduced
`briefly.
`FIG. 1 shows an example of OFDM channel characteris
`tics.
`Here, two horizontal axes respectively indicate OFDM
`symbols on the time domain and Subcarrier numbers on the
`frequency domain, and the vertical axis indicates channel
`gains corresponding to OFDM symbols and Subcarriers.
`OFDM channels fluctuates in both time domain and fre
`quency domain as a result of time domain spreading and time
`domain spreading of channels in transmission.
`As described above, the concept of AMC is to change
`modulation and coding parameters in transmission based on
`channel characteristics at this current time. With OFDM,
`
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`5
`
`10
`
`15
`
`25
`
`35
`
`3
`guard intervals inserted by guard interval insertion section
`305. The bits are then transmitted via antenna 306. On the
`receiving side in FIG.3B, after receiving transmission signals
`transmitted from the transmission side via receiving antenna
`316, guard interval removing section 315 removes the guard
`intervals inserted on the transmission side. Further, the signal
`then passes through serial/parallel converter (S/P) 314 and
`fast Fourier transformer (FFT)313 to be converted from time
`domain to frequency domain symbols. The signals are then
`Subjected to parallel/serial conversion processing by parallel/
`serial converter (P/S) 312 and are finally outputted by adap
`tive demodulating/decoding section 311 to obtain received
`data.
`Adaptive transmission from the transmission side of FIG.
`3A to the receiving side of FIG.3B is implemented mainly by
`adaptive modulation/coding section 301 on the transmission
`side and adaptive demodulating/decoding section 311 on the
`receiving side. As described above, the meaning of adaptive
`modulation and coding is to adaptively adjust modulation and
`coding parameters on the transmission side based on channel
`characteristics at the current time and to carry out demodula
`tion and decoding using parameters corresponding to the
`transmission side on the receiving side. In a typical system,
`adaptive parameters required by adaptive demodulating/de
`coding section 311 depend on feedback from the receiving
`side. Before transmitting each data block, the receiving side
`always first estimates transmission channel from the trans
`mission side to the receiving side at the current time by
`channel estimating section 319, and obtains channel charac
`30
`teristics of the subcarriers of the OFDM. Based on these
`channel characteristics, the receiving side then decides modu
`lation and coding parameters used for the OFDM subbands in
`the case of transmitting data from the transmission side at the
`current point by parameter selecting section 318. Parameters
`for adaptive modulation and coding at the Subbands obtained
`by parameter selecting section 318 have two uses.
`The first use is the use as a parameter for modulation and
`coding at each OFDM subband when the transmission side
`transmits data at the current time. After selecting modulation
`and coding parameters of the OFDM Subbands, subband
`AMC parameter selecting section 318 on the receiving side
`then transmits these parameters back to the transmission side
`via a feedback path of receiving side parameter transmitting
`section 320, antenna 316 on the receiving side, antenna 306
`on the transmission side, and parameter receiving/extracting
`section 307 on the transmission side. After extracting these
`parameters, the transmission side controls adaptive modula
`tion/coding section 301 using AMC control section 308.
`The second use is the use as a parameter when the receiving
`side carries out demodulation and decoding. In AMC trans
`mission, the receiving side is able to obtain accurate informa
`tion bits for the first time by carrying out demodulation and
`decoding of received data based on modulation and coding
`parameters that are always the same as in the transmitting
`side. Subband AMC parameter selecting section 318 obtains
`and then transmits AMC parameters to adaptive demodulat
`ing/decoding section 317, and adaptive demodulating/decod
`ing section 317 temporarily saves the AMC parameter. The
`AMC parameter needs to be used in control of adaptive
`demodulating/decoding section 311 on the receiving side.
`In FIG. 4A and FIG. 4B, module 309 of FIG. 3A and
`module 321 of FIG. 3B are segmented to describe a method
`for employing subband AMC in OFDM of the related art in a
`clearer manner.
`FIG. 4A and FIG. 4B show configurations for implement
`ing Subband adaptive modulation/coding of the related art.
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`On the transmission side of FIG.3A, adaptive modulating/
`coding section 301 is comprised of adaptive coding section
`401, interleave section 402, and adaptive modulation section
`403. Data outputted from adaptive modulating/coding section
`301 is transmitted to inverse fast Fourier transformer (IFFT)
`303 via serial/parallel converter (S/P) 302. Transmission side
`AMC control section 308 controls adaptive modulating/cod
`ing section 301 based on modulation and coding parameters
`for the subbands obtained from parameter receiving/extract
`ing section 307 of FIG. 3A. In subband adaptivity of the
`related art, coding modulation is carried out independently
`for the OFDM Subbands. Namely, all subbands have respec
`tive independent modulation and coding parameters. AMC
`control section 308 controls adaptive modulating/coding sec
`tion 301 using the obtained coding parameters C and modu
`lation parameters M for the subbands. Further, AMC control
`section 308 obtains the number of information bits transmit
`ted at the Subbands based on the coding parameters C and
`modulation parameters M. generates a corresponding inter
`leave matrix IT as a result, and controls interleave section 402
`of adaptive modulating/coding section 301. On the transmis
`sion side, after AMC, a serial data stream 404 is obtained.
`This contains data transmitted in the order of Subband 1,
`2, ... N, with modulation and coding methods of (C. M.),
`(CM), . . . . (C. M.), respectively. After this, this data is
`Subjected to serial/parallel conversion and is then sequen
`tially mapped to subbands corresponding to OFDM and is
`transmitted.
`All of the AMC parameters necessary in transmission of
`the data blocks on the transmission side are fed back from the
`receiving side. Namely, before the transmission side trans
`mits the data blocks, the receiving side first needs to select
`AMC parameters for use in the data blocks that the transmis
`sion side transmits. In the procedure where the receiving side
`selects parameters first, channel estimation is carried out
`using the received signal. A method based on a pilot or blind
`channel estimation etc. may be given as a method of channel
`estimation. After this, channel estimation section 319 trans
`mits channel characteristics of the obtained OFDM subcarri
`ers to subband AMC parameter selecting section 318. Sub
`band AMC parameter selecting section 318 first carries out
`analysis of the performance of the subbands in OFDM in this
`way, and selects AMC parameters appropriate for the respec
`tive subbands from the selected set of AMC parameters. AMC
`parameters obtained in this way are then transmitted back to
`the transmission side via a feedback channel, and are used in
`actual adaptive modulation and coding operations when the
`transmission side carries out transmission, and also used at
`adaptive demodulating/decoding control section 409 on the
`receiving side. At the same time, taking time delay into con
`sideration, parameter storing section 410 is necessary for
`storing parameters obtained at the current time. Adaptive
`demodulating/decoding section 311 on the receiving side is
`comprised of adaptive decoding section 408, deinterleaving
`section 407 and adaptive decoding section 406.
`Compared to subcarrier adaptivity, the adaptive method
`using independent coding of Subbands of the related art
`shown in FIG. 3A to FIG. 4B is able to effectively reduce the
`difficulty of implementation of adaptivity and is able to effec
`tively reduce feedback overhead of the system. However,
`even in this kind of method, there is the drawback that it is not
`possible to effectively utilize diversity performance between
`the subbands.
`Diversity is an important method for improving wireless
`transmission quality. The diversity referred to here is gener
`ally described as technology where the transmitting side
`increases redundancy of information using a certain resource
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`5
`and modifies or attenuates redundant information on both of
`the receiving side and the transmission side independently as
`much as possible, and, the receiving side utilizes and synthe
`sizes the information in a collective manner, thereby obtain
`ing a certain system gain. To Summarize, this is technology
`where transmission is carried out simultaneously by utilizing
`a plurality of paths, and deficiencies in certain paths on the
`receiving side is compensated for by other paths.
`In addition to the foundation of an independent coding
`method using Subbands in OFDM adaptive modulation and
`coding of the related art, the present application is to obtain a
`patent for a method for combining Subbands using a certain
`method, assuming the Subbands as a Subband group, then
`carrying out joint coding for subband groups. With AMC
`methods of the related art, a parameter is selected and coding
`15
`is carried out for each Subband independently, and, the
`method of the present application therefore seems to run
`counter to the concept of AMC of the related art in appear
`ance. However, this method adopts diversity between sub
`bands and is therefore able to obtain a larger coding gain.
`Further, if selection of modulation coding parameters is car
`ried out within Subband groups using the method proposed
`here, loss in transmission throughput is not generated com
`pared with the method of the related art. By combining both,
`the method for which the present application seek a patent
`promotes improvement of adaptive transmission perfor
`mance in OFDM.
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`DISCLOSURE OF THE INVENTION
`
`Problems to be Solved by the Invention
`
`The object of the present invention is therefore to provide
`communication apparatus, a communication system and a
`communication method capable of increasing spectrum ulti
`lization rate of a system and particularly increasing spectrum
`utilization rate based on high-speed fading and channel esti
`mation error, reducing the degree of difficulty of adaptivity,
`and reducing the feedback overhead compared with Subband
`adaptive methods of the related art by combining all of the
`Subbands on a frequency domain of a Subcarrier communica
`tion system based on a fixed rule to as to give several Subband
`groups, and then selecting modulation and coding parameters
`for use during joint coding with respect to each Subband
`group.
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`Means for Solving the Problem
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`A communication apparatus of the present invention
`adopts a configuration having: a channel estimating section
`that carries out channel estimation per Subband; a parameter
`deciding section that decides modulation parameters and cod
`ing parameters per Subband group comprised of a plurality of
`Subbands based on the channel estimation result, a parameter
`information transmission section that transmits to a commu
`nicating party, parameter information that is information for
`55
`the modulation parameters and the coding parameters
`decided at the parameter deciding section; a receiving section
`that receives a received signal containing data modulated and
`encoded per Subband group at a communicating party using
`the modulation parameters and coding parameters of the
`parameter information transmitted at the parameter informa
`tion transmission section; and a data obtaining section that
`demodulates and decodes the received signal received at the
`receiving section per Subband group using the modulation
`parameters and coding parameters decided at the parameter
`deciding section and obtains the data contained in the
`received signal.
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`6
`A communication system of the present invention is a
`communication system having a base station apparatus trans
`mitting modulated and encoded data and a communication
`terminal apparatus receiving the data, and adopting a configu
`ration having the communication terminal apparatus com
`prising: a channel estimating section that carries out channel
`estimation per Subband; a parameter deciding section that
`decides modulation parameters and coding parameters per
`Subband group comprised of a plurality of Subbands based on
`channel estimation results; a parameter information transmis
`sion section that transmits parameter information that is
`information for the modulation parameters and the coding
`parameters decided at the parameter deciding section; a
`receiving section that receives a received signal containing
`data modulated and encoded per Subband group at the base
`station apparatus using parameters of parameter information
`transmitted at the parameter information transmission sec
`tion; and a data extracting section that modulates and decodes
`a received signal received at the receiving section per Subband
`group using the modulation parameters and the coding
`parameters of the parameter information and extracts the data
`contained in the received signal, and, in this system, the base
`station apparatus comprises an adaptive modulating/coding
`section that modulates and encodes data in accordance with
`the modulation parameters and coding parameters of the
`parameter information transmitted by the transmission sec
`tion; and a data transmission section that transmits data
`modulated and encoded at the adaptive modulating/coding
`section.
`A communication method of the present invention having
`the steps of carrying out channel estimation per Subband;
`deciding modulation parameters and coding parameters per
`Subband group comprised of a plurality of Subbands based on
`the channel estimation results; at a communication terminal
`apparatus, transmitting parameter information that is infor
`mation for the decided modulation parameters and coding
`parameters; at a base station apparatus, receiving the param
`eter information transmitted by the communication terminal
`apparatus; modulating and coding data inaccordance with the
`modulation parameters and the coding parameters of the
`received parameter information; at the base station apparatus,
`transmitting the modulated and encoded data; at the commu
`nication terminal apparatus, receiving a received signal con
`taining the data transmitted by the base station apparatus; and
`modulating and decoding the received signal per Subband
`group using the modulation parameters and the coding
`parameters of the parameter information, and extracting data
`contained in the received signal.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIG. 1 shows an example of OFDM channel characteris
`tics;
`FIG. 2 shows adaptive modulation and coding of the
`related art;
`FIG. 3A is a block view showing a configuration for the
`transmission side of an OFDM-AMC system of the related
`art,
`FIG. 3B is a block view showing a configuration for the
`receiving side of an OFDM-AMC system of the related art;
`FIG. 4A shows a module containing an adaptive modulat
`ing/coding section on a transmission side of the related art;
`FIG. 4B shows a module containing an adaptive demodu
`lating/decoding section on a receiving side of the related art;
`FIG. 5A is a block view showing a configuration for the
`transmission side of an OFDM-AMC system of an embodi
`ment of the present invention;
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`US 7,848,439 B2
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`7
`FIG. 5B is a block view showing a configuration for the
`receiving side of an OFDM-AMC system of an embodiment
`of the present invention;
`FIG. 6A shows a module containing an adaptive modulat
`ing/coding section on a transmission side of an embodiment
`of the present invention;
`FIG. 6B shows a module containing an adaptive demodu
`lating/decoding section on a receiving side of an embodiment
`of the present invention;
`FIG. 7 shows an adaptive modulation and coding method
`of an embodiment of the present invention;
`FIG.8 shows an example of a subband group of an embodi
`ment of the present invention;
`FIG. 9 shows another example of a subband group of an
`embodiment of the present invention;
`FIG. 10 shows yet another example of a subband group of
`an embodiment of the present invention;
`FIG. 11 shows the comparison results of performance of
`adaptive modulation and coding of an embodiment of the
`present invention and adaptive modulation and coding of the
`related art; and
`FIG. 12 shows other comparison results of performance of
`adaptive modulation and coding of an embodiment of the
`present invention and adaptive modulation and coding of the
`related art.
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`of the related art the units of the subband adaptive modulation
`and coding are subbands. With The present invention, all of
`the subbands in the frequency domain in OFDM are made
`into several Subband groups using combination patterns, and
`adaptive modulation and coding then are performed on the
`subband groups. Further, with the OFDM-AMC system of the
`present invention, AMC parameters relating to Subband
`groups as parameter information that is information for
`modulation parameters and coding parameters, are transmit
`ted in a feedback route of a series in the order of parameter
`transmitting section 320, receiving side antenna 316, trans
`mission side antenna 306 and transmission side parameter
`receiving/extracting section 307, rather than the AMC para