CN103179064A

CN103179064A - 8PSK (phase shifting key) planisphere

Info

Publication number: CN103179064A
Application number: CN 201310085872
Authority: CN
Inventors: 谭明新; 杨颖�
Original assignee: Individual
Current assignee: Individual
Priority date: 2013-03-18
Filing date: 2013-03-18
Publication date: 2013-06-26

Abstract

Disclosed is an 8PSK (phase shifting key) planisphere which indicates linear relation between Euclidean distance between constellations and code distance between digital codes. When the Euclidean distance between constellation points is small, code distance between digital codes is small, and the defect that smaller phase shift in a conventional planisphere leads to large number error is avoided. When Euclidean distance between the constellation points is large, code distance between digital codes is large. When Euclidean distance between the constellation points is maximum, code distance between digital codes is the maximum. Random errors on channels are in direct proportion to Euclidean distance between the constellation points, namely, random errors are gradually accumulated to result in changes of digital information. Compared with the prior art, phase change gradually increase on the premise of normal operation of the 8PSK planisphere, and change caused by information distortion of the same degree is accordant with practical information changes on random channels.

Description

The 8PSK planisphere

Technical field

The invention belongs to the digital phase moudlation technical field, relate in particular to the 8PSK planisphere.

Background technology

Digital modulation technique especially digital phase moudlation technology (PSK) is the basic fundamental that the large capacity digital system adopts.In digital communication, although the theoretical research of PSK has reached high-order, commercial PSK technology is the distortion of BPSK, QPSK or QPSK normally.Next step may enter commercial PSK technology on a large scale is 8PSK.

(these documents and model mainly contain the Modulation and Coding for Wireless Communications of 1. Alister Burr, page40 to existing modulation /demodulation authority document 8PSK model; 2. the Modulation and coding techniques in wireless communications of Sergei Semenov and Evgenii Krouk, page47; 3. the Digital Modulation Techniques of Fuqin Xiong, second edition. page150; 4. the Wireless communications of Goldsmith, page136) relation of the Euclidean distance between represented constellation and code distance, there is following shortcoming: 1, the larger constellation point of part Euclidean distance, the maximum that the code distance of represented digital code has, some minimums; And Euclidean distance is at a distance of farthest constellation point, and the code distance of represented digital code is not maximum.2, on channel, larger interference or noise might cause 1 bit or 3 bit generation mistakes in 3 represented bit informations of 8PSK constellation.

During according to above-mentioned document design, be not in worst situation if the random noise of channel causes phase shift, may cause the most serious information distortion.The result that the solution timing causes is: the constellation point that phase shift is larger, code distance is minimum or maximum, that is to say, the most serious situation of error code might occur.Generally to correct by channel code because of the mistake due to modulation /demodulation.In present error-correcting code technique, cyclic code commonly used realizes the correction of 1 bit error; And more than or equal to the error correcting technique of 2 bit errors, usually correct with BCH code, convolution code or Turbo code (or being about to enter commercial LDPC code), but at this moment decoding complexity has increased many and has caused the increase of cost, and this is the particular problem that must face in Realization of Product.That is to say, when Euclidean distance is not maximum, corresponding channel error may not reach maximum, causes mistake may exceed the error correcting capability of channel code.Therefore, the novel 8PSK planisphere that needs design more to meet the random noise characteristic overcomes defects.

Summary of the invention

The present invention between constellation Euclidean distance and represented digital code between the relation of code distance, designed the better 8PSK planisphere of performance, the described planisphere of its complete authoritative list of references different from the past.In newly-designed planisphere, the code distance between described planisphere between the size of Euclidean distance and represented digital code is linear, has avoided phase shift larger in conventional constellation figure may cause the drawback of maximum number mistake.Reduced simultaneously because of the mistake due to modulation /demodulation, reduced the cost of error correcting code decoding complexity.

In order to solve the problems of the technologies described above, the invention provides a kind of newly-designed 8PSK planisphere.A kind of 8PSK planisphere, the code distance between constellation between the size of Euclidean distance and represented digital code is linear; Euclidean distance between constellation point hour, the code distance between digital code is less, has avoided phase shift less in conventional constellation figure may cause the drawback of greater number mistake; When the Euclidean distance between constellation point was larger, the code distance between digital code was larger; When the Euclidean distance between constellation point was maximum, the code distance between digital code was maximum; Random error on channel is directly proportional to Euclidean distance between described constellation point, that is, random error builds up the variation that causes digital information.Compared with prior art, 8PSK planisphere of the present invention is in the situation that normal operation, and phase place changes when running up to gradually very greatly, and the variation that the information distortion of equal extent causes will conform to the information actual change on accidental channel.The planisphere of design will reduce the erroneous judgement of separating timing like this, avoid the error correcting code complexity to increase and the cost increase that causes.

By following description also by reference to the accompanying drawings, it is more clear that the present invention will become, and these accompanying drawings are used for explaining embodiments of the invention.

Description of drawings

Fig. 1 is the 8PSK planisphere of present authoritative document.

Fig. 2 is the 8PSK planisphere of present authoritative document.

Fig. 3 is the 8PSK planisphere of present authoritative document.

Fig. 4 is the 8PSK planisphere of present authoritative document.

Fig. 5 is 8PSK planisphere of the present invention.

Fig. 6 is 8PSK planisphere of the present invention.

Fig. 7 is 8PSK planisphere of the present invention.

Fig. 8 is 8PSK planisphere of the present invention.

Fig. 9 is the information distortion figure when random error occurring on channel in 8PSK planisphere shown in Figure 5.

Figure 10 is the information distortion figure when random error occurring on channel in 8PSK planisphere shown in Figure 6.

Figure 11 is Fig. 1 to the 8PSK planisphere of present authoritative document shown in Figure 4, the code distance graph of a relation of the Euclidean distance digital code represented with it between constellation.

Figure 12 is Fig. 5 to 8PSK planisphere shown in Figure 8, the code distance graph of a relation of the Euclidean distance digital code represented with it between constellation.

Embodiment

With reference now to accompanying drawing, describe embodiments of the invention, capitalization A, B in accompanying drawing, C, D, E, F, G, H represent 8 constellation point, and the numeral of constellation point mark is the three digital bit code informations that constellation point represents.As mentioned above, between this invention constellation, the size of Euclidean distance and the code distance between represented digital code are linear, thereby have strengthened antijamming capability.

Elaborate the technical scheme of the embodiment of the present invention below in conjunction with accompanying drawing, wherein Fig. 6 is formed by Fig. 5 22.5o that turns clockwise, and is also a kind of variation diagram of 8PSK planisphere shown in Figure 5.Each constellation point three bit consists of characteristics as shown in Figure 5:

1) the 1st bit is determined by the y axle of reference axis: when constellation was positioned at y axle right side, the 1st bit was 0; When constellation was positioned at y axle left side, the 1st bit was 1;

2) the 2nd bit is determined by the x axle of reference axis: when constellation point was positioned at x axle top, the 2nd bit was 0; When constellation was positioned at x axle below, the 2nd bit was 1;

3) the 3rd bit is united definite by reference axis x and y.In 8 constellations of 8PSK, it is that 0, two the 3rd bit near the x axle is 1 that two the 3rd bits near the x axle are arranged; Two the 3rd bits near the y axle are 0; Two the 3rd bits near the y axles are 1, guarantee the consistent of Euclidean distance and code distance.

The planisphere of signal if occur random error on channel, might cause information distortion after determining, the thresholding of the information distortion of 8PSK planisphere shown in Figure 5 can be used respectively A as shown in Figure 9 ₁, B ₁, C ₁, D ₁, E ₁, F ₁, G ₁, H ₁Represent, Figure 10 is the information distortion figure of 8PSK planisphere as shown in Figure 6.What in fact, these points were corresponding is the decision threshold of phase shift.For example, establish the corresponding information source information of constellation A, following variation may occur in the A on channel:

(1) if cause constellation A at A because of the variation of phase place ₁With B ₁Between (perhaps H ₁With G ₁Between) when changing, former constellation A will be mistaken for constellation B(or H in receiving end);

(2) if cause constellation A at B because of the variation of phase place ₁With C ₁Between (perhaps G ₁With F ₁Between) when changing, former constellation A will be mistaken for constellation C(or G in receiving end);

(3) if cause constellation A at C because of the variation of phase place ₁With D ₁Between (perhaps F ₁With E ₁Between) when changing, former constellation A will be judged to constellation D(or F in receiving end);

(4) if because of the variation of phase place cause constellation A and between when changing, former constellation A will be judged to constellation E in receiving end;

(5) if constellation A at A ₁With H ₁Between when changing, receiving end still can correctly be recovered the represented signal of former constellation A.

In above-mentioned 5 kinds of situations, only have the distortion of (5) little, can correctly adjudicate; Distortion has occured in (1) ~ (4).4 kinds of distortion bit numbers corresponding to situation are respectively 1 bit (1 bit), 1 bit (2 bit), 2 bits (2 bit), 3 bits.And, can calculate, the represented Euclidean distance of decision threshold of (1) ~ (4) is respectively:

To 8PSK planisphere shown in Figure 8, can draw the relation of Euclidean distance between the 8PSK constellation and represented digital code code distance as shown in figure 12, wherein according to Fig. 5 xAxle represents the Euclidean distance between constellation, yAxle represents the code distance between the constellation digital code.For the ease of relatively, Figure 11 has provided the relation of the Euclidean distance between the 8PSK constellation and represented digital code code distance in present authoritative document.

In Figure 11, Figure 12, the right number of numeral constellation on line; When between constellation, Euclidean distance is identical, if code distance d _iThe right number of constellation more than or equal to code distance d _mThe right number of constellation, code distance d _iLine represent with solid line, otherwise dot, purpose is the process for outstanding saltus step.When between the Euclidean distance between the constellation that draws by Fig. 1-4 as can be seen from Figure 11, and represented digital code character, the relation of code distance is and ascending, descending.And as can be seen from Figure 12, between the Euclidean distance between the constellation that draws by Fig. 5-8 and represented digital code character, the relation of code distance is consistent.Therefore, the planisphere of design reduces to understand the erroneous judgement of timing like this, has avoided following situation: larger but not maximum phase shift may cause the drawback of maximum number mistake.

Claims

1.8PSK planisphere is characterized in that: the code distance between constellation between the size of Euclidean distance and represented digital code is linear.

2. 8PSK planisphere according to claim 1 is characterized in that: the Euclidean distance between described constellation point hour, the code distance between digital code is less, has avoided phase shift less in conventional constellation figure may cause the drawback of greater number mistake.

3. 8PSK planisphere according to claim 1, it is characterized in that: when the Euclidean distance between described constellation point was larger, the code distance between digital code was larger.

4. 8PSK planisphere according to claim 1 is characterized in that: when the Euclidean distance between described constellation point was maximum, the code distance between digital code was maximum.

5. 8PSK planisphere according to claim 1 is characterized in that: the random error on channel is directly proportional to Euclidean distance between described constellation point, that is, random error builds up the variation that causes digital information.