JP2713443B2 - Useless bit elimination method in multi-level modulation - Google Patents
Useless bit elimination method in multi-level modulationInfo
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- JP2713443B2 JP2713443B2 JP63290761A JP29076188A JP2713443B2 JP 2713443 B2 JP2713443 B2 JP 2713443B2 JP 63290761 A JP63290761 A JP 63290761A JP 29076188 A JP29076188 A JP 29076188A JP 2713443 B2 JP2713443 B2 JP 2713443B2
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Description
【発明の詳細な説明】 〔概要〕 複数の伝送速度に対応する超高速モデムの多値変調に
おける無駄ビット削除方式に関し、 S/N特性の改善を図ることができることを目的とし、 多値信号を信号点に配置して変調する多値変調方式に
おいて、多値の第１のビット数に対応する数の信号点が
設定され、入力多値信号を前記信号点のいずれかに配置
する第１の信号点配置手段と、第１のビット数とは異な
る多値の第２のビット数に対応する信号点が設定され、
入力多値信号を信号点のいずれかに配置する第２の信号
点配置手段と、複数の伝送速度のそれぞれに対して、適
用される最高速の伝送速度に対応した変調速度での変調
であって、且つその１変調で用いられるビット数を伝送
速度に応じたビット数として決められる第１及び第のビ
ット数を、第１の信号点配置手段および第１の信号点配
置手段に設定する制御手段と、入力多値信号を第１の信
号点配置手段あるいは第２の信号点配置手段の一方に、
伝送速度と変調速度との関係に応じて求められる所定の
割合により選択して入力させる選択手段とを備え、第１
の信号点配置手段に設定される信号点と、第２の信号点
配置手段に設定される信号点とは、信号点間距離が等し
くなるようにして請求項１記載の発明は構成される。DETAILED DESCRIPTION OF THE INVENTION [Summary] The present invention relates to a method of eliminating useless bits in multi-level modulation of an ultra-high-speed modem corresponding to a plurality of transmission speeds. In a multi-level modulation method of arranging and modulating signals at signal points, a number of signal points corresponding to a first number of bits of multi-values are set, and a first signal of arranging an input multi-level signal at any of the signal points is set. Signal point allocating means, and signal points corresponding to a multi-valued second bit number different from the first bit number are set;
A second signal point arranging means for arranging the input multi-level signal at one of the signal points; and a modulation at a modulation rate corresponding to the highest applied transmission rate for each of the plurality of transmission rates. And setting the first and second bit numbers, which determine the number of bits used in one modulation as the number of bits according to the transmission rate, in the first signal point arranging means and the first signal point arranging means. Means and the input multi-valued signal to one of the first signal point constellation means or the second signal point constellation means,
Selecting means for selecting and inputting at a predetermined ratio determined according to the relationship between the transmission rate and the modulation rate,
The signal point set in the signal point arranging means and the signal point set in the second signal point arranging means are configured such that the distance between the signal points is equal.
請求項２記載の発明は、最高速の伝送速度より低速な
伝送速度においても最高速の伝送速度に対応した変調速
度での変調に用いられる信号点間距離に等値の信号点間
距離で第１の多値信号の信号点の配置を行い、等値の信
号点間距離で第２の多値信号の信号点の配置を行って変
調され、伝送されて来た多値変調信号を復調する多値復
調方式において、受信された多値変調信号を前記第１お
よび第２の多値信号に対応する信号点の配置にそれぞれ
復調する復調手段と、復調手段の出力信号を選択信号に
応じた第１および第２の選択出力に出力する選択手段
と、選択手段の各別の出力に接続され、選択手段から出
力された信号点の配置を対応する多値信号に再生する第
１および第２の信号点再生手段と、伝送されて来た多値
変調信号の伝送速度情報および前記復調手段に設定され
た前記最高速の伝送速度に対応した復調速度から決めら
れる割合で復調手段を対応する信号点再生手段に接続さ
せる選択信号を出力し、且つ該選択信号対応の信号点再
生手段を動作させる制御手段とを備えて請求項２記載の
発明は構成される。The invention according to claim 2 is a signal transmission method that uses a signal point distance equal to a signal point distance used for modulation at a modulation rate corresponding to the highest transmission rate even at a transmission rate lower than the highest transmission rate. One multi-level signal signal point is arranged, and the second multi-level signal signal point is arranged at an equal distance between signal points to demodulate the transmitted multi-level modulated signal. In the multi-level demodulation system, demodulation means for demodulating a received multi-level modulation signal to an arrangement of signal points corresponding to the first and second multi-level signals, and an output signal of the demodulation means according to a selection signal. Selection means for outputting to the first and second selection outputs, and first and second means connected to respective different outputs of the selection means for reproducing the arrangement of signal points output from the selection means into corresponding multi-level signals Signal point reproducing means, and transmission speed information of the transmitted multilevel modulation signal. And outputting a selection signal for connecting the demodulation means to the corresponding signal point reproduction means at a rate determined from the demodulation rate corresponding to the highest transmission rate set in the demodulation means, and outputting a signal point corresponding to the selection signal. The invention according to claim 2 is provided with control means for operating the reproduction means.
本発明は、複数の伝送速度に対応する超高速モデムに
おいて、S/N特性の改善を図ることができる多値変調方
式における無駄ビット削除方式および多値復調方式に関
する。The present invention relates to a multi-level modulation scheme capable of improving S / N characteristics in an ultra-high-speed modem corresponding to a plurality of transmission speeds, and relates to a multi-level modulation scheme and a useless bit elimination scheme.
超高速モデムでは、多値化と変調速度を上げることに
より、伝送速度（データ信号速度）の高速化が実現され
ているが、回線の周波数帯域幅あるいは信号点間距離に
応じたS/N特性（エラーレート）を考慮する必要があ
り、最適な信号点数および変調速度が選択されている。In ultra-high-speed modems, the transmission speed (data signal speed) has been increased by increasing the number of levels and the modulation speed. However, the S / N characteristics according to the frequency bandwidth of the line or the distance between signal points have been realized. (Error rate) must be taken into consideration, and an optimal number of signal points and modulation speed are selected.
すなわち、変調速度は回線の帯域幅により取り得る最
大の値が決定されるが、たとえば2400bpsの伝送速度で
ベースバンド・パルスを伝送するためには、1200Hzの最
小帯域幅が必要であり、変調に必要な帯域幅はその２倍
（実際にはロールオフ係数のためにそれ以上が必要）で
あるので、周波数変調方式では2400ボーの変調速度（帯
域幅2400Hz）で、2400bpsの伝送速度が限界になってい
る。In other words, the maximum possible modulation speed is determined by the bandwidth of the line.For example, transmitting a baseband pulse at a transmission speed of 2400 bps requires a minimum bandwidth of 1200 Hz. The required bandwidth is twice that (actually more is needed due to the roll-off factor), so the frequency modulation method has a limit of 2400 baud at a modulation rate of 2400 baud (2400 Hz bandwidth). Has become.
一方、たとえば16（＝24）値直交振幅変調（QAM）方
式の信号を変調速度2400ボーで変調すれば、9600（2400
×４）bpsの伝送速度を実現することができ、同一帯域
幅の回線で４倍の伝送速度の実現が可能になっている。On the other hand, for example, if a signal of 16 (= 2 4 ) value quadrature amplitude modulation (QAM) method is modulated at a modulation speed of 2400 baud, 9600 (2400)
* 4) A transmission speed of bps can be realized, and a transmission speed four times as high as that of a line having the same bandwidth can be realized.
このように、変調速度を上げることによる高速化は、
変調速度が回線の帯域幅に対応しているために限界があ
り、多値化による高速化は、信号点間の距離が短くなる
ことによるS/N特性の劣化が大きくなるので、その最適
化が図られていた。As described above, the speed up by increasing the modulation speed is as follows.
Since the modulation speed corresponds to the bandwidth of the line, there is a limit, and high-speed operation by multi-valued optimization is necessary because deterioration of S / N characteristics due to shortening of the distance between signal points increases. Was planned.
また、従来の超高速モデムでは、複数の伝送速度に対
応できる構成を有しているが、変調速度は最高伝送速度
に対応して設定される。すなわち、たとえば最高伝送速
度が19.2k bpsの超高速モデムでは、128（＝27）値直交
振幅変調方式の場合に対応して、変調速度（シンボル速
度）は2742.8571（＝19200÷７）ボーに設定される。Further, the conventional ultra-high-speed modem has a configuration capable of supporting a plurality of transmission rates, but the modulation rate is set corresponding to the maximum transmission rate. Thus, for example in ultra-high speed modems the highest transmission rate is 19.2k bps, 128 (= 2 7 ) value corresponds to the case of quadrature amplitude modulation system, modulation rate (symbol rate) is 2742.8571 (= 19200 ÷ 7) to Bo Is set.
ところが、この超高速モデムでは、他の伝送速度、た
とえば16.8k bps,14.4k bps,12.0k bps,9.6k bpsに対し
ては、各伝送速度をその変調速度で割った値（１変調で
変調されるビット数）が整数値にならない場合（それぞ
れ6.125,5.25,4.375,3.5）が生ずる。However, in this ultra-high-speed modem, for other transmission speeds, for example, 16.8 kbps, 14.4 kbps, 12.0 kbps, and 9.6 kbps, each transmission speed is divided by its modulation speed (modulation by one modulation). (The number of bits to be performed) does not become an integer value (6.125, 5.25, 4.375, and 3.5, respectively).
すなわち、伝送速度が16.8k bpsの場合（6.125）に
は、１変調で変調されるビット数が７ビットの変調方式
（128値直交振幅変調方式）をとれば、８シンボル（変
調周期）に７ビットの無駄ビットが生じていることにな
る。また、伝送速度が14.4k bpsの場合（5.25）には、
１変調で変調されるビット数が６ビットの変調方式（64
値直交振幅変調方式）をとれば、４シンボルに３ビット
の無駄ビットが生じていることになる。That is, when the transmission rate is 16.8 kbps (6.125), if a modulation method in which the number of bits modulated by one modulation is 7 bits (128-ary quadrature amplitude modulation method) is used, 7 symbols (modulation cycle) are used. This means that bits are wasted. If the transmission speed is 14.4 kbps (5.25),
A modulation method in which the number of bits modulated by one modulation is 6 bits (64
Value quadrature amplitude modulation method), it means that three useless bits occur in four symbols.
このように、それぞれ８シンボルで７ビット、４シン
ボルで３ビット、８シンボルで５ビット、２シンボルで
１ビットの各無駄ビットが発生し、S/N特性の劣化が生
じる問題点があった。As described above, there are problems that 7 symbols are used for 8 symbols, 3 bits for 4 symbols, 5 bits for 8 symbols, and 1 bit for 2 symbols, and the S / N characteristic is deteriorated.
本発明は、このような従来の問題点を解決するもの
で、無駄ビットを削除してS/N比の改善と同時に、多値
変調部および多値復調部の共用化等を図り得る多値変調
方式における無駄ビット削除方式および多値復調方式を
提供することを目的とする。The present invention solves such a conventional problem, and improves the S / N ratio by eliminating useless bits, and at the same time, enables multi-level modulation and demodulation to be shared. An object of the present invention is to provide a waste bit elimination method and a multi-level demodulation method in a modulation method.
第１図（その１）は、請求項１記載の発明の原理ブロ
ック図を示す。FIG. 1 (part 1) shows a principle block diagram of the first aspect of the present invention.
図に示すように、請求項１記載の発明は、多値信号を
信号点に配置して変調する多値変調方式に、第１の信号
点配置手段111と、第２の信号点配置手段113と、制御手
段117と、選択信号115とを備えて構成される。As shown in the figure, the first aspect of the present invention relates to a multi-level modulation system for arranging and modulating a multi-level signal at a signal point. , Control means 117, and a selection signal 115.
第１の信号点配置手段111は、多値の第１のビット数
に対応する数の信号点が設定され、入力多値信号を前記
信号点のいずれかに配置する。The first signal point arranging means 111 sets the number of signal points corresponding to the multi-valued first bit number, and arranges the input multi-level signal at any of the signal points.
第２の信号点配置手段113は、前記第１のビット数と
は異なる多値の第２のビット数に対応する信号点が設定
され、入力多値信号を前記信号点のいずれかに配置す
る。The second signal point arrangement means 113 sets signal points corresponding to a multi-valued second bit number different from the first bit number, and arranges an input multi-valued signal at any of the signal points. .
制御手段117は、複数の伝送速度のそれぞれに対し
て、適用される最高速の伝送速度に対応した変調速度で
の変調であって、且つその１変調で用いられるビット数
を伝送速度に応じたビット数として決められる第１及び
第２のビット数を、前記第１の信号点配置手段111およ
び前記第１の信号点配置手段113に設定する。The control unit 117 performs modulation at a modulation rate corresponding to the highest transmission rate applied to each of the plurality of transmission rates, and adjusts the number of bits used in one of the modulations according to the transmission rate. First and second bit numbers determined as the number of bits are set in the first signal point arrangement means 111 and the first signal point arrangement means 113.
選択手段115は、入力多値信号を前記第１の信号点配
置手段111あるいは前記第２の信号点配置手段113の一方
に、伝送速度と変調速度との関係に応じて求められる所
定の割合により選択して入力させる。The selecting means 115 transmits the input multi-level signal to one of the first signal point arranging means 111 and the second signal point arranging means 113 by a predetermined ratio obtained according to the relationship between the transmission rate and the modulation rate. Select and input.
そして、前記第１の信号点配置手段111に設定される
信号点と、前記第２の信号点配置手段113に設定される
信号点とは、信号点間距離が等しくなるようにして請求
項１記載の発明の全体が構成される。The signal point set in the first signal point arranging means 111 and the signal point set in the second signal point arranging means 113 have the same signal point distance. The whole of the described invention is constituted.
第１図（その２）は、請求項２記載の発明の原理ブロ
ック図を示す。FIG. 1 (part 2) is a block diagram showing the principle of the second aspect of the present invention.
請求項２記載の発明は、最高速の伝送速度より低速な
伝送速度においても最高速の伝送速度に対応した変調速
度での変調に用いられる信号点間距離に等値の信号点間
距離で第１の多値信号の信号点の配置を行い、前記等値
の信号点間距離で第２の多値信号の信号点の配置を行っ
て変調され、伝送されて来た多値変調信号を復調する多
値復調方式に、復調手段121と、選択手段125と、第１お
よび第２の信号点再生手段127,129と、制御手段131とを
備えて構成される。The invention according to claim 2 is a signal transmission method that uses a signal point distance equal to a signal point distance used for modulation at a modulation rate corresponding to the highest transmission rate even at a transmission rate lower than the highest transmission rate. 1, the signal points of the multi-level signal are arranged, the signal points of the second multi-level signal are arranged at the distance between the equal signal points, and the modulated multi-level modulated signal is demodulated. The multi-level demodulation method includes a demodulation unit 121, a selection unit 125, first and second signal point reproduction units 127 and 129, and a control unit 131.
前記復調手段121は、受信された多値変調信号を前記
第１および第２の多値信号に対応する信号点の配置にそ
れぞれ復調する。The demodulation means 121 demodulates the received multi-level modulated signal to an arrangement of signal points corresponding to the first and second multi-level signals.
前記選択手段125は、前記復調手段121の出力信号を選
択信号に応じた第１および第２の選択出力に出力する。The selection means 125 outputs the output signal of the demodulation means 121 to first and second selection outputs according to the selection signal.
前記第１および第２の信号点再生手段127,129は、前
記選択手段125の各別の出力に接続され、前記選択手段1
25から出力された信号点の配置を対応する多値信号に再
生する。The first and second signal point reproducing means 127 and 129 are connected to different outputs of the selecting means 125, respectively.
The arrangement of the signal points output from 25 is reproduced to the corresponding multilevel signal.
前記制御手段131は、伝送されて来た多値変調信号の
伝送速度情報および前記復調手段121に設定された前記
最高速の伝送速度に対応した復調速度から決められる割
合で前記復調手段121を対応する信号点再生手段127,129
に接続させる選択信号を出力し、且つ該選択信号対応の
信号点再生手段127,129を動作させる。The control means 131 corresponds to the demodulation means 121 at a rate determined from the transmission rate information of the transmitted multi-level modulation signal and the demodulation rate corresponding to the highest transmission rate set in the demodulation means 121. Signal point reproducing means 127,129
Is output, and the signal point reproducing means 127 and 129 corresponding to the selection signal are operated.
請求項１記載の発明は、選択手段115で、入力多値信
号を伝送速度と変調速度との関係に応じて決まる割合で
選択して第１の信号点配置手段111および第２の信号点
配置手段113の一方へ入力し、そのようにして入力され
た入力多値信号を当該信号点配置手段で信号点の信号点
間距離を等しくするようにして入力多値信号のビット数
に対応する数の信号点を１変調毎に配置する。According to the first aspect of the present invention, the selection means 115 selects the input multi-valued signal at a ratio determined according to the relationship between the transmission rate and the modulation rate, and selects the first signal point arrangement means 111 and the second signal point arrangement. A signal corresponding to the number of bits of the input multi-valued signal by inputting the input multi-valued signal to one of the means 113 and making the distance between signal points of the signal points equal by the signal point arrangement means. Are arranged for each modulation.
この配置に用いられる１変調毎のビット数は、最高速
の伝送速度に対応した変調速度での変調が行われるその
１変調で用いられるビット数を伝送速度に応じたビット
数として決められる数に設定される。The number of bits for each modulation used in this arrangement is a number determined by setting the number of bits used in the one modulation to be determined as the number of bits corresponding to the transmission rate, at which the modulation is performed at the modulation rate corresponding to the highest transmission rate. Is set.
このように構成することにより、速度を低下させて多
値信号を伝送する際の平均の送信エネルギーを低下させ
得るから、S/N比を向上させ得る。又、その伝送される
多値変調信号の信号点間距離は、同一にされているの
で、多値変調信号を伝送速度を変えて伝送するに際し
て、信号の信号振幅を何ら変更する必要性は無くなり、
多値変調部の共用化、そしてこれにより回路規模の小型
化を達成し得る。With this configuration, it is possible to reduce the average transmission energy when transmitting a multi-level signal at a reduced speed, and thus to improve the S / N ratio. Further, since the distance between signal points of the transmitted multi-level modulated signal is the same, there is no need to change the signal amplitude of the signal when transmitting the multi-level modulated signal at a different transmission speed. ,
The multi-level modulation section can be shared, and thereby the circuit size can be reduced.
請求項２記載の発明は、前記復調手段121で受信され
る多値変調信号を第１および第２の多値信号に対応する
信号点の配置に復調し、復調された信号点の配置を前記
制御手段131により制御される選択手段125を経て前記制
御手段131により制御される前記第１および第２の信号
点再生手段127,129に選択的に入力する。前記第１およ
び第２の信号点再生手段127,129から信号点の配置に対
応する多値信号を再生する。According to a second aspect of the present invention, the multi-level modulation signal received by the demodulation means 121 is demodulated into an arrangement of signal points corresponding to the first and second multi-level signals, and the arrangement of the demodulated signal points is changed. The signal is selectively input to the first and second signal point reproducing means 127 and 129 controlled by the control means 131 via the selection means 125 controlled by the control means 131. The first and second signal point reproducing means 127 and 129 reproduce multilevel signals corresponding to the arrangement of signal points.
S/N比が向上された多値変調信号の復調となるから、
復調性能の向上を図ることができる。又、その伝送され
て来る多値変調信号の信号点間距離は、同一にされてい
るので、多値変調信号の復調に多値変調信号の信号振幅
についての何ら処理の必要性はなくなり、多値変調部の
共用化、そしてこれにより回路規模の小型化を達成し得
る。Since it becomes demodulation of the multi-level modulation signal with the improved S / N ratio,
Demodulation performance can be improved. In addition, since the distance between signal points of the transmitted multi-level modulation signal is the same, there is no need to perform any processing on the signal amplitude of the multi-level modulation signal in demodulating the multi-level modulation signal. The value modulator can be shared, and the circuit size can be reduced.
以下、図面に基づいて請求項１および請求項２記載の
発明の実施例について詳細に説明する。Hereinafter, embodiments of the invention described in claims 1 and 2 will be described in detail with reference to the drawings.
第２図は、請求項１および請求項２記載の発明の一実
施例の構成を示すブロック図である。FIG. 2 is a block diagram showing a configuration of an embodiment of the invention described in claims 1 and 2.
なお、第２図（ａ）は送信部における本発明実施例の
要部構成（請求項１記載の発明に相当する。）であり、
第２図（ｂ）は受信部における本発明実施例の要部構成
（請求項２記載の発明に相当する。）である。FIG. 2 (a) shows a main configuration (corresponding to the invention described in claim 1) of the transmission unit in the embodiment of the present invention.
FIG. 2 (b) shows a configuration of a main part of an embodiment of the present invention in the receiving section (corresponding to the second aspect of the present invention).
図において、送信部では、送信信号が符号器211に入
力され、その符号化信号が切替器213を介していずれか
一方の信号点発生回路215,217に入力され、その出力が
変調器219を介して送信される構成である。In the figure, in the transmission unit, a transmission signal is input to an encoder 211, the encoded signal is input to one of signal point generation circuits 215 and 217 via a switch 213, and the output is input via a modulator 219. This is the configuration to be transmitted.
また、受信部では、入力信号が復調器213で復調さ
れ、その復調信号が切替器233を介していずれか一方の
信号点再生回路235,237に入力され、その出力が復号器2
39を介して復号化され、受信信号として送出される構成
である。In the receiving unit, the input signal is demodulated by the demodulator 213, the demodulated signal is input to one of the signal point regeneration circuits 235 and 237 via the switch 233, and the output is
In this configuration, the data is decoded via the transmission line 39 and transmitted as a reception signal.
ここで、伝送速度情報に応じて所定の制御信号を送出
する制御回路221,241は、信号点発生回路215,217および
信号点再生回路235,237に、１変調で変調されるビット
数（信号点配置）の設定制御を行ない、さらに各切替器
213,233の切り替え制御を行なう。Here, the control circuits 221 and 241 that transmit a predetermined control signal in accordance with the transmission rate information have the signal point generation circuits 215 and 217 and the signal point reproduction circuits 235 and 237 set and control the number of bits modulated by one modulation (signal point arrangement). And each switch
213,233 switching control is performed.
制御回路221,241は、請求項１の制御手段117,請求項
２の制御手段131に相当する。信号点発生回路215,217
は、請求項１の第１の信号点配置手段111,第２の信号点
配置手段113に相当する。信号点再生回路235,237は、請
求項１の第１の信号点再生手段127,第２の信号点再生手
段129に相当する。切替器213,233は、請求項１の選択手
段115,請求項２の選択手段125に相当する。The control circuits 221 and 241 correspond to the control means 117 of the first aspect and the control means 131 of the second aspect. Signal point generation circuit 215,217
Corresponds to the first signal point arrangement means 111 and the second signal point arrangement means 113 of claim 1. The signal point reproducing circuits 235 and 237 correspond to the first signal point reproducing means 127 and the second signal point reproducing means 129 of the first aspect. The switches 213 and 233 correspond to the selecting means 115 of claim 1 and the selecting means 125 of claim 2.
なお、各制御回路221,241は、送信部および受信部に
おいて基本的には同様の制御処理を行なうので、ここで
は送信部における動作について詳細に説明する。Since each of the control circuits 221 and 241 basically performs the same control processing in the transmission unit and the reception unit, the operation in the transmission unit will be described in detail here.
制御回路221は、まず指定される伝送速度に応じて、
各信号点発生回路215,217にそれぞれ１変調で変調され
る所定のビット数を設定する。たとえば、伝送速度が1
6.8k bit/sの場合には、１変調で変調されるビット数を
それぞれ７ビットおよび６ビットに設定し、各信号点発
生回路215,217で128値直交振幅変調方式および64値直交
振幅変調方式のそれぞれに対応する信号点配置を行な
う。The control circuit 221 firstly, according to the specified transmission speed,
A predetermined number of bits to be modulated by one modulation is set in each of the signal point generation circuits 215 and 217. For example, if the transmission speed is 1
In the case of 6.8 kbit / s, the number of bits modulated by one modulation is set to 7 bits and 6 bits, respectively, and the signal point generation circuits 215 and 217 use the 128-value quadrature amplitude modulation method and the 64-value quadrature amplitude modulation method. The corresponding signal point arrangement is performed.
続いて、切替器213の切り替え周期を指定される伝送
速度に応じた所定の比率に設定する。たとえば、伝送速
度が16.8k bit/sの場合には、信号点数128の信号点発生
回路215と、信号点数64の信号点発生回路217の切り替え
比率を１対７に設定する。Subsequently, the switching cycle of the switch 213 is set to a predetermined ratio according to the specified transmission speed. For example, when the transmission speed is 16.8 kbit / s, the switching ratio between the signal point generating circuit 215 having 128 signal points and the signal point generating circuit 217 having 64 signal points is set to 1: 7.
すなわち、伝送速度が16.8k bit/sの場合には、８シ
ンボル中１シンボルは１変調で変調されるビット数（信
号点数）を７ビット（128値）にし、８シンボル中７シ
ンボルは１変調で変調されるビット数（信号点数）を６
ビット（64値）にして伝送する。That is, when the transmission rate is 16.8 kbit / s, the number of bits (signal points) modulated by one modulation is set to 7 bits (128 values) for one of eight symbols, and seven of eight symbols are modulated for one symbol. The number of bits (signal points) modulated by
Transmit with bits (64 values).
ここで、最高伝送速度が19.2k bpsの超高速モデム
で、128（＝27）値直交振幅変調方式に対応して、変調
速度が2742.8571（19.2k/7）ボーに設定されている場合
について、他の伝送速度に対応して各信号点発生回路21
5,217に設定されるビット数（信号点数）、および切替
器213の切り替え周期の一例を次表に示す。Here, the maximum transmission rate is very fast modem 19.2k bps, corresponding to 128 (= 2 7) quadrature amplitude modulation scheme, the case where the modulation rate is set to 2,742.8571 (19.2k / 7) Bo , Each signal point generation circuit 21 corresponding to other transmission speeds
An example of the number of bits (number of signal points) set to 5,217 and the switching cycle of the switch 213 are shown in the following table.
このように、伝送速度が16.8k bit/sの場合には、８
シンボル中７シンボルが64値で伝送され（従来はすべて
128値で伝送）、以下同様に信号点数が少なくなった分
だけ送信エネルギーが小さくなるので、その平均エネル
ギーを小さくすることが可能になる。 Thus, when the transmission rate is 16.8 kbit / s, 8
Seven of the symbols are transmitted as 64 values (conventionally all
In the same manner, the transmission energy is reduced by the decrease in the number of signal points, so that the average energy can be reduced.
第３図は、信号点数128（＝27）と信号点数64（＝
26）の各信号点配置の一例を示す図である。Figure 3 is a signal number 128 (= 2 7) and the signal points 64 (=
FIG. 26 is a diagram illustrating an example of each signal point arrangement of 26 ).
ここで、信号点間の距離を２とすれば、128値の場合
の平均エネルギーは82、64値の場合の平均エネルギーは
42である。Here, if the distance between signal points is 2, the average energy in the case of 128 values is 82, and the average energy in the case of 64 values is
42.
したがって、伝送速度が16.8k bit/sの場合に、従来
の方式であれば無駄ビットであるために、８シンボル間
の平均エネルギーは82（＝82×8/8）であるが、本発明
方式であれば無駄ビットがなく、その平均エネルギーは
47（＝（82＋42×７）/8）となり、そのS/N特性は、 の改善を実現することができる。Therefore, when the transmission rate is 16.8 kbit / s, the average energy between eight symbols is 82 (= 82 × 8/8) because of the useless bits in the conventional method, but the method of the present invention. Then there is no wasted bit and the average energy is
47 (= (82 + 42 × 7) / 8), and its S / N characteristic is Can be improved.
なお、受信部（第２図（ｂ））においては、制御回路
241は、指定される伝送速度に応じて、各信号点再生回
路235,237にそれぞれ所定の信号点数が設定され、さら
に１変調で変調されるビット数が決定される。たとえ
ば、伝送速度が16.8k bit/sの場合には、各信号点再生
回路235,237で128値直交振幅変調方式および64値直交振
幅変調方式のそれぞれに対応する信号点配置を行ない、
１変調で変調されるビット数をそれぞれ７ビットおよび
６ビットに設定する。In the receiving section (FIG. 2 (b)), the control circuit
In 241, a predetermined number of signal points is set in each of the signal point reproduction circuits 235 and 237 in accordance with the designated transmission speed, and the number of bits modulated by one modulation is determined. For example, when the transmission rate is 16.8 kbit / s, signal point arrangement corresponding to each of the 128-value quadrature amplitude modulation method and the 64-value quadrature amplitude modulation method is performed in each signal point reproduction circuit 235, 237,
The number of bits modulated by one modulation is set to 7 bits and 6 bits, respectively.
このように、受信部では受信部の動作と逆の動作とな
るが、本発明の基本的な制御処理を変更するものではな
い。As described above, the operation of the receiving unit is the reverse of the operation of the receiving unit, but does not change the basic control processing of the present invention.
また、本実施例に示した伝送速度、変調速度、信号点
数はその一例であり、またそれらに対応する選択手段
（切替器）の選択パターンを含めて、本実施例に限定さ
れるものではない。Further, the transmission speed, the modulation speed, and the number of signal points shown in the present embodiment are only examples, and the present invention is not limited to the present embodiment, including the selection pattern of the selecting means (switch) corresponding thereto. .
請求項１記載の発明によれば、速度を低下させて多値
信号を伝送する際の平均の送信エネルギーを低下させ得
るから、S/N比を向上させ得る。又、その伝送される多
値変調信号の信号点間距離は、同一にされているので、
多値変調信号を伝送速度を変えて伝送するに際して、信
号の信号振幅を何ら変更する必要性は無くなり、多値変
調部の共用化、そしてこれにより回路規模の小型化を達
成し得る。According to the first aspect of the present invention, the average transmission energy at the time of transmitting a multi-level signal at a reduced speed can be reduced, so that the S / N ratio can be improved. Also, since the distance between signal points of the transmitted multi-level modulation signal is the same,
When transmitting a multi-level modulated signal at a different transmission speed, there is no need to change the signal amplitude of the signal, and the multi-level modulation section can be shared, and thereby the circuit size can be reduced.
また、請求項２記載の発明によれば、S/N比が向上さ
れた多値変調信号の復調となるから、復調性能の向上を
図ることができる。又、その伝送されて来る多値変調信
号の信号点間距離は、同一にされているので、多値変調
信号の復調に多値変調信号の信号振幅についての何ら処
理の必要性はなくなり、多値変調部の共用化、そしてこ
れにより回路規模の小型化を達成し得る。Further, according to the second aspect of the present invention, demodulation of a multilevel modulated signal with an improved S / N ratio can be achieved, so that demodulation performance can be improved. In addition, since the distance between signal points of the transmitted multi-level modulation signal is the same, there is no need to perform any processing on the signal amplitude of the multi-level modulation signal in demodulating the multi-level modulation signal. The value modulator can be shared, and the circuit size can be reduced.
第１図は請求項１および請求項２記載の発明の原理ブロ
ック図、 第２図は請求項１および請求項２記載の発明の一実施例
の構成を示すブロック図、 第３図は信号点数128（＝27）と信号点数64（＝26）の
各信号点配置の一例を示す図である。 図において、 111,113は信号点配置手段、115は選択手段、117は制御
手段、211は符号器、213は切替器、215,217は信号点発
生回路、219は変調器、221は制御回路、231は復調器、2
33は切替器、235,237は信号点再生回路、239は復号器、
241は制御回路である。FIG. 1 is a block diagram showing the principle of the invention according to claims 1 and 2, FIG. 2 is a block diagram showing the configuration of an embodiment of the invention according to claims 1 and 2, and FIG. It is a figure which shows an example of each signal point arrangement | sequence of 128 (= 2 < 7 >) and 64 signal points (= 2 < 6 >). In the figure, 111 and 113 are signal point arrangement means, 115 is selection means, 117 is control means, 211 is an encoder, 213 is a switch, 215 and 217 are signal point generation circuits, 219 is a modulator, 221 is a control circuit, and 231 is demodulation. Bowl, 2
33 is a switch, 235 and 237 are signal point reproduction circuits, 239 is a decoder,
241 is a control circuit.
Claims (2)
変調方式において、 多値の第１のビット数に対応する数の信号点が設定さ
れ、入力多値信号を前記信号点のいずれかに配置する第
１の信号点配置手段と、 前記第１のビット数とは異なる多値の第２のビット数に
対応する信号点が設定され、入力多値信号を前記信号点
のいずれかに配置する第２の信号点配置手段と、 複数の伝送速度のそれぞれに対して、適用される最高速
の伝送速度に対応した変調速度での変調であって、且つ
その１変調で用いられるビット数を伝送速度に応じたビ
ット数として決められる第１及び第２のビット数を、前
記第１の信号点配置手段および前記第１の信号点配置手
段に設定する制御手段と、 入力多値信号を前記第１の信号点配置手段あるいは前記
第２の信号点配置手段の一方に、伝送速度と変調速度と
の関係に応じて求められる所定の割合により選択して入
力させる選択手段と、を備え、 且つ前記第１の信号点配置手段に設定される信号点と、
前記第２の信号点配置手段に設定される信号点とは、信
号点間距離が等しいことを特徴とする、多値変調方式に
おける無駄ビット削除方式。1. A multi-level modulation system for arranging and modulating a multi-level signal at a signal point, wherein a number of signal points corresponding to a first bit number of a multi-level signal are set, and an input multi-level signal is converted to the signal point. A signal point corresponding to a multi-valued second number of bits different from the first number of bits, and an input multi-level signal is assigned to the signal point. A second signal point arranging means arranged at any one of the plurality of transmission rates, and a modulation at a modulation rate corresponding to the highest transmission rate applied to each of the plurality of transmission rates, and one modulation is used for the modulation. Control means for setting first and second bit numbers determined as the number of bits according to the transmission rate in the first signal point arrangement means and the first signal point arrangement means; A value signal from the first signal point arrangement means or the second signal point arrangement means. One of the signal point arranging means is provided with selecting means for selecting and inputting at a predetermined ratio determined according to the relationship between the transmission rate and the modulation rate, and is set in the first signal point arranging means. Signal points,
The signal point set in the second signal point arranging means has an equal distance between signal points, and a waste bit elimination method in a multi-level modulation method.
いても最高速の伝送速度に対応した変調速度での変調に
用いられる信号点間距離に等値の信号点間距離で第１の
多値信号の信号点の配置を行い、前記等値の信号点間距
離で第２の多値信号の信号点の配置を行って変調され、
伝送されて来た多値変調信号を復調する多値復調方式に
おいて、 受信された多値変調信号を前記第１および第２の多値信
号に対応する信号点の配置にそれぞれ復調する復調手段
と、 前記復調手段の出力信号を選択信号に応じた第１および
第２の選択出力に出力する選択手段と、 該選択手段の各別の出力に接続され、前記選択手段から
出力された信号点の配置を対応する多値信号に再生する
第１および第２の信号点再生手段と、 伝送されて来た多値変調信号の伝送速度情報および前記
復調手段に設定された前記最高速の伝送速度に対応した
復調速度から決められる割合で前記復調手段を対応する
信号点再生手段に接続させる選択信号を出力し、且つ該
選択信号対応の信号点再生手段を動作させる制御手段と を備えて構成したことを特徴とする多値復調方式。2. The method according to claim 1, wherein, even at a transmission rate lower than the highest transmission rate, the first multiple signal signal distance is equal to a signal point distance used for modulation at a modulation rate corresponding to the highest transmission rate. The signal points of the value signal are arranged, and the signal points of the second multi-level signal are arranged and modulated at the distance between the signal points of the same value.
In a multi-level demodulation method for demodulating a transmitted multi-level modulation signal, demodulation means for demodulating a received multi-level modulation signal to an arrangement of signal points corresponding to the first and second multi-level signals, respectively. Selecting means for outputting an output signal of the demodulating means to first and second selection outputs according to a selection signal; connecting to each other output of the selecting means, and selecting a signal point output from the selecting means First and second signal point reproducing means for reproducing the arrangement into a corresponding multi-valued signal; transmission rate information of the transmitted multi-level modulated signal and the highest transmission rate set in the demodulation means. Control means for outputting a selection signal for connecting the demodulation means to the corresponding signal point reproduction means at a ratio determined from the corresponding demodulation speed, and operating the signal point reproduction means corresponding to the selection signal. Characterized by Multi-level demodulation method.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63290761A JP2713443B2 (en) | 1988-11-16 | 1988-11-16 | Useless bit elimination method in multi-level modulation |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63290761A JP2713443B2 (en) | 1988-11-16 | 1988-11-16 | Useless bit elimination method in multi-level modulation |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH02135841A JPH02135841A (en) | 1990-05-24 |
| JP2713443B2 true JP2713443B2 (en) | 1998-02-16 |
Family
ID=17760191
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP63290761A Expired - Fee Related JP2713443B2 (en) | 1988-11-16 | 1988-11-16 | Useless bit elimination method in multi-level modulation |
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| Country | Link |
|---|---|
| JP (1) | JP2713443B2 (en) |
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|---|---|---|---|---|
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|---|---|---|---|---|
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1988
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| Publication number | Publication date |
|---|---|
| JPH02135841A (en) | 1990-05-24 |
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