JPH0118613B2 - - Google Patents
Info
- Publication number
- JPH0118613B2 JPH0118613B2 JP58236935A JP23693583A JPH0118613B2 JP H0118613 B2 JPH0118613 B2 JP H0118613B2 JP 58236935 A JP58236935 A JP 58236935A JP 23693583 A JP23693583 A JP 23693583A JP H0118613 B2 JPH0118613 B2 JP H0118613B2
- Authority
- JP
- Japan
- Prior art keywords
- synchronization
- likelihood
- subchannel
- decoding
- likelihood function
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 238000007476 Maximum Likelihood Methods 0.000 claims description 11
- 238000000034 method Methods 0.000 claims description 7
- 230000001360 synchronised effect Effects 0.000 description 3
- 239000013598 vector Substances 0.000 description 3
- 230000005540 biological transmission Effects 0.000 description 2
- 238000005562 fading Methods 0.000 description 2
- 238000004364 calculation method Methods 0.000 description 1
- 239000000284 extract Substances 0.000 description 1
- 230000008054 signal transmission Effects 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L5/00—Arrangements affording multiple use of the transmission path
- H04L5/02—Channels characterised by the type of signal
- H04L5/06—Channels characterised by the type of signal the signals being represented by different frequencies
Landscapes
- Engineering & Computer Science (AREA)
- Signal Processing (AREA)
- Computer Networks & Wireless Communication (AREA)
- Dc Digital Transmission (AREA)
- Synchronisation In Digital Transmission Systems (AREA)
Description
【発明の詳細な説明】
本発明は複数のサブキヤリアに変調をかけて伝
送する周波数多重通信方式において、パイロツト
信号の挿入なしにビツト同期やフレーム同期をと
る方式に関する。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for achieving bit synchronization and frame synchronization without inserting a pilot signal in a frequency division multiplex communication method in which a plurality of subcarriers are modulated and transmitted.
従来の周波数多重通信方式において、ビツト同
期やフレーム同期を受信側で確立するために、デ
ータを伝送するには複数のサブキヤリア以外に、
クロツク信号やフレーム同期信号を伝送するため
のパイロツトキヤリアを別に設け、上記クロツク
信号やフレーム同期信号で該パイロツトキヤリア
に変調をかける方式が一般的に行われている。通
常パイロツトキヤリアは固定された周波数スロツ
トに挿入されているので、この周波数スロツトに
フエージングや混信等の妨害があると、ビツト同
期やフレーム同期が崩れ正確な同期が確立できな
いという欠点があつた。 In conventional frequency multiplex communication systems, in order to establish bit synchronization and frame synchronization on the receiving side, in addition to multiple subcarriers, data transmission is required.
A commonly used method is to provide a separate pilot carrier for transmitting a clock signal or a frame synchronization signal, and to modulate the pilot carrier with the clock signal or frame synchronization signal. Usually, the pilot carrier is inserted into a fixed frequency slot, so if there is interference such as fading or interference in this frequency slot, bit synchronization and frame synchronization will be broken, making it impossible to establish accurate synchronization.
本発明は、これらの欠点を除去するために、各
サブチヤネルに同期信号を付価し、受信側で各サ
ブチヤネル毎に最尤復号を行い、この最尤復号に
ともなつて算出される尤度関数または尤度関数差
から復号時点における最良の復号品質を持つサブ
チヤネルを選択し、そのサブチヤネルの同期信号
により同期を確立するようにしたもので、以下図
面により詳細に説明する。 In order to eliminate these drawbacks, the present invention attaches a synchronization signal to each subchannel, performs maximum likelihood decoding for each subchannel on the receiving side, and calculates a likelihood function based on this maximum likelihood decoding. Alternatively, the subchannel having the best decoding quality at the time of decoding is selected from the likelihood function difference, and synchronization is established using the synchronization signal of that subchannel.This will be explained in detail below with reference to the drawings.
最尤復号法の基本的原理を説明すると、送信側
では送信データに対してたたみ込み符号等で符号
化して、受信側へ送信する。受信側では(1)式で表
わされる尤度関数を算出する。 To explain the basic principle of the maximum likelihood decoding method, on the transmitting side, the transmitted data is encoded using a convolutional code or the like, and then transmitted to the receiving side. On the receiving side, a likelihood function expressed by equation (1) is calculated.
Ｐ（〓｜〓）＝〓i（yi｜al i） …(1)
ただし、〓は受信データ系列ベクトルであり、
〓＝（y1，y2，…yi，…），〓は送信符号化器によ
つて決まるｌ番目に出力されるデータ系列ベクト
ルであり、〓＝（al 1，al 2，……al i…）である。 P(〓｜〓)=〓 i (y i ｜a l i ) …(1) However, 〓 is the received data sequence vector,
〓 = (y 1 , y 2 , ... y i , ...), 〓 is the l-th output data sequence vector determined by the transmission encoder, 〓 = (a l 1 , a l 2 , ... … al i … ).
送信側符号化器によつて決まるすべてのデータ
系列ベクトルに対して(1)式の尤度関数を計算し、
算出された尤度関数及びそれに対応するデータ系
列のすべてを記憶しておく、ある長さ計算後記憶
されている尤度関数の中で一番大なる尤度関数に
対応するデータ系列を順次受信データとして出力
する誤り訂正方式の一種であることは周知の事実
である。即ち、最尤復号法とは、受信側で送信デ
ータ系列に最も近いと思われるデータ系列を選び
出すことであり、(1)式より受信系列Ｙに誤りがあ
れば、尤度関数は小さくなる。したがつて尤度関
数とは、受信データに対する復号品質を表わす関
数である。(1)式で算出される尤度関数列のうち最
大のものと、２番目に大なる尤度関数の差は、誤
りが多ければその差は小さくなり、誤り数が一定
であると、その差もほぼ一定であるという性質が
あり、この尤度関数差も、受信データに対する復
号品質を表わす関数である。 Calculate the likelihood function of equation (1) for all data sequence vectors determined by the transmitter encoder,
All of the calculated likelihood functions and their corresponding data series are stored, and after a certain length calculation, the data series corresponding to the largest likelihood function among the stored likelihood functions is sequentially received. It is a well-known fact that this is a type of error correction method that outputs data. That is, the maximum likelihood decoding method is to select a data sequence that is considered to be closest to the transmitted data sequence on the receiving side, and according to equation (1), if there is an error in the received sequence Y, the likelihood function becomes smaller. Therefore, the likelihood function is a function that represents the decoding quality of received data. The difference between the largest likelihood function sequence calculated by equation (1) and the second largest likelihood function becomes smaller if there are many errors, and if the number of errors is constant, The difference also has the property of being approximately constant, and this likelihood function difference is also a function representing the decoding quality of received data.
以上説明したように、尤度関数または尤度関数
差が、復号時点における復号品質を表わすことに
着目し、まず送信側で全部または複数のサブキヤ
リアに第１図に示すように、同期信号（ビツトお
よびフレームの各同期信号）をデータの前に付加
して伝送する。受信側では、上記同期信号を付加
したサブチヤネルすべてに対し、各々上記最尤復
号を行い、復号にともなつてビツト毎に算出され
る尤度関数または尤度関数差（以下LFと言う。）
をビツト毎または複数ビツト平均した値を監視
し、同期信号の付加されたサブチヤネルの中で最
大のLFまたはLFの平均値を持つサブチヤネルを
選択し、該サブチヤネルより復調されてくるデー
タにより遂次ビツト同期及びフレーム同期の監視
を行う。 As explained above, focusing on the fact that the likelihood function or the likelihood function difference represents the decoding quality at the time of decoding, first, on the transmitting side, a synchronization signal (bit and frame synchronization signals) are added to the front of the data and transmitted. On the receiving side, the maximum likelihood decoding is performed on all the subchannels to which the synchronization signal has been added, and the likelihood function or likelihood function difference (hereinafter referred to as LF) is calculated for each bit during decoding.
monitors the average value for each bit or multiple bits, selects the subchannel with the maximum LF or LF average value among the subchannels to which the synchronization signal is added, and sequentially uses the data demodulated from the subchannel to Monitors synchronization and frame synchronization.
第２図は本発明の一実施例で、ａは送信側、ｂ
は受信側を示し、これはサブチヤネル数をｎとし
た場合である。１は同期信号発生器、２はｎケの
符号化器、３はｎケの変調器、４は送信機、５は
受信機、６はｎケの最尤復号器、７は判定器、８
は同期回路である。この動作は、第１図に示すよ
うに、データ送出前に同期信号発生器１で発生す
る同期信号（ビツト及びフレーム）を送出し、そ
の後にデータを送出する。これらの信号は、符号
化器２でそれぞれ符号化し、変調器３によりf1〜
foの周波数に変調し、送信機４から受信側へ送出
する。受信側では受信機５で受信された各サブチ
ヤネルに対応する信号は、最尤復号器６によりそ
れぞれ最尤復号を行い、判定器７により、上記最
尤復号で算出されるLFの中で一番大なるLFを持
つサブチヤネルの復号データを同期回路８に出力
する。この同期回路８では、クロツクタイミング
を抽出してビツト同期をとるとともに、フレーム
信号を監視する。フレーム同期が確立されると、
データを出力端に送出する。このような動作によ
り常に復号時点における最良サブチヤネルを選択
し、そのサブチヤネル同期信号により同期を確立
することができる。 FIG. 2 shows an embodiment of the present invention, where a is the transmitting side, b
indicates the receiving side, and this is when the number of subchannels is n. 1 is a synchronization signal generator, 2 is n coders, 3 is n modulators, 4 is a transmitter, 5 is receiver, 6 is n maximum likelihood decoders, 7 is a determiner, 8
is a synchronous circuit. In this operation, as shown in FIG. 1, a synchronization signal (bits and frames) generated by a synchronization signal generator 1 is sent out before data is sent out, and then data is sent out. These signals are each encoded by an encoder 2, and modulated by a modulator 3 into f 1 ~
The signal is modulated to the frequency f o and sent from the transmitter 4 to the receiving side. On the receiving side, the signals corresponding to each subchannel received by the receiver 5 are subjected to maximum likelihood decoding by a maximum likelihood decoder 6, and a decider 7 determines which LF is the best among the LFs calculated by the maximum likelihood decoding. The decoded data of the subchannel having a large LF is output to the synchronization circuit 8. This synchronization circuit 8 extracts the clock timing and establishes bit synchronization, and also monitors the frame signal. Once frame synchronization is established,
Sends data to the output end. By such an operation, it is possible to always select the best subchannel at the time of decoding and establish synchronization using the subchannel synchronization signal.
以上説明したように、本発明は復号時点で一番
誤りの少ないサブチヤネルにより同期を確立する
ことができ、時々刻々と変化するフエージングや
混信等のある回線においても、常に最良の同期信
号で同期を確立できるという利点がある。 As explained above, the present invention is able to establish synchronization using the subchannel with the least errors at the time of decoding, and even in lines with constantly changing fading and interference, synchronization is always achieved using the best synchronization signal. It has the advantage of being able to establish
第１図は同期信号伝送フオーマツト、第２図は
本発明の一実施例である。
１……同期信号発生器、２……符号化器、３…
…変調器、４……送信機、５……受信機、６……
最尤復合器、７……判定器、８……同期回路。
FIG. 1 shows a synchronous signal transmission format, and FIG. 2 shows an embodiment of the present invention. 1... Synchronization signal generator, 2... Encoder, 3...
...Modulator, 4...Transmitter, 5...Receiver, 6...
Maximum likelihood decoder, 7...determiner, 8...synchronous circuit.
Claims (1)
送出する周波数多重通信方式において、複数のサ
ブチヤネルの送信データの前に同期信号を付加し
て符号化し、受信側で各サブチヤネル毎に最尤復
号を行つて、これにともなつて算出される尤度関
数または尤度関数差のうち、一番大なる尤度関数
または尤度関数差を持つサブチヤネルから復号さ
れた同期信号で同期を確立することを特徴とする
同期方式。1 In a frequency division multiplex communication system that modulates data on multiple subchannels and sends it out, a synchronization signal is added and encoded in front of the transmitted data of multiple subchannels, and maximum likelihood decoding is performed on each subchannel on the receiving side. , synchronization is established using a synchronization signal decoded from a subchannel having the largest likelihood function or likelihood function difference among the likelihood functions or likelihood function differences calculated accordingly. synchronization method.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP58236935A JPS60128735A (en) | 1983-12-15 | 1983-12-15 | Synchronizing system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP58236935A JPS60128735A (en) | 1983-12-15 | 1983-12-15 | Synchronizing system |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS60128735A JPS60128735A (en) | 1985-07-09 |
| JPH0118613B2 true JPH0118613B2 (en) | 1989-04-06 |
Family
ID=17007925
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP58236935A Granted JPS60128735A (en) | 1983-12-15 | 1983-12-15 | Synchronizing system |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS60128735A (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0744529B2 (en) * | 1987-03-20 | 1995-05-15 | 富士通株式会社 | Frame synchronization control method |
| JPH01135147A (en) * | 1987-11-20 | 1989-05-26 | Oki Electric Ind Co Ltd | Data transmission system |
| JPH0284836A (en) * | 1988-09-20 | 1990-03-26 | Fujitsu Ltd | Error correction method for multicarrier radio transmission system |
-
1983
- 1983-12-15 JP JP58236935A patent/JPS60128735A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS60128735A (en) | 1985-07-09 |
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