JP3537702B2 - Spread spectrum communication equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spread spectrum communication apparatus, and more particularly, to an ARQ system, which delays a spread spectrum signal of a direct spread system by an arbitrary number of chips and multiplexes the signal. The present invention relates to a spread-spectrum communication system.

[0002]

2. Description of the Related Art Recently, LAN (Loca) has been used in offices.
l Networking through the construction of an area network (local area network) has been progressing, but wireless applications have attracted attention because of their application to portable devices and the idea of free office layout. Currently available wireless LAN is 256K
IEEE, which has a transmission speed of ~ 2 Mbps (bits per second) and is internationally standardizing wireless LAN
The standard of 1-2 Mbps is also being summarized in 802.11. However, with the recent development of information processing technology, the amount of information to be transmitted has been greatly increased, and therefore, a higher transmission speed is required for wireless LANs.

On the other hand, in the home, new information communication devices such as a personal computer, a digital camera, a portable information tool called a PDA (Personal Digital Assistant), and a video phone have appeared, and these devices are portable and exchange information. In order to enhance simplicity, wireless communication means between them has been required. Many of these devices handle image and moving image information so that they can be used more enjoyably in ordinary households. For these reasons, there is an increasing demand for a high-speed wireless transmission system that can withstand data communication including images and real-time transmission of moving images. In response to such a demand, a delay multiplexing system using direct spectrum spreading that enables transmission at a maximum of 10 Mbps has been proposed (Japanese Patent Laid-Open No. Hei 10-229383). This method uses I
It has upward compatibility with the EEE802.11 standard, can be realized with a slight increase in circuit scale, and can be multi-rate with the same occupied bandwidth.

FIG. 12 shows a system configuration of the delay multiplexing system, and FIG. 13 shows a packet format. In FIG. 12, 1 is a demodulation unit, 2 is a reception side data processing unit, 3 is an upper layer, 4 is a transmission data processing unit, 5 is a modulation unit, 6 is a multiplex number control unit, 10 is an antenna, and 11 is a changeover switch. Show.
In this communication device, the transmission signal can be multiplexed in the modulation section 5, and the multiplexed transmission signal from another terminal can be received in the demodulation section 1. That is, data can be transmitted and received at a transmission speed that is a multiple of the multiplex number.
The multiplex number can be changed, and the multiplex number control unit 6
Performs the control.

FIG. 14 shows a portion of the baseband signal processing of the modulation section 5 in FIG. The input signal is subjected to serial / parallel conversion (Serial / Parallel conversion) by the S / P converter 10, multiplied by the spreading code from the spreading code generator 12 by the multiplier 13, and delayed by the respective time by the delay unit 14. After multiplexing. FIG. 15 shows Q1, Q2, Q3, Q4,
5 shows the structure of a signal at the time of 5-multiplexing in Q5. Multiplexing becomes possible by shifting the signals thus spread little by little. In the case other than the five multiplexing, for example, in the case of two multiplexing, the S / P converter 10 is controlled so that the output of the S / P converter 10 in FIG. 14 is changed from five to two outputs Q11 and Q12. This is realized by controlling the delay time of the delay unit 14. FIG. 16 shows the configuration of signals at Q1 to Q5 in FIG. 14 at this time.

The control of the multiplex number is performed as follows. At the time of packet transmission, as shown in FIG.
And the data section 1302 is multiplexed. At this time, the multiplex number of the data section 1302 is written in the header section 1301. At the time of packet reception, first, the header unit 130
1 is demodulated, the multiplex number in the header section is read, and the multiplexed data section 1302 is demodulated using the multiplex number.

[0007] The number of multiplexes of the data part at the time of packet transmission is determined as follows. It is assumed that data is transmitted from terminal A to terminal B. In the delay multiplexing method, the ARQ method (Auto
matic Repeat reQuest (automatic retransmission request method). The ARQ scheme is a communication protocol for transmitting data without error. Each time the terminal B receives data from the terminal A, it determines whether or not an error has occurred in the data. Acknowledgement: Acknowledgment, if present, NAK (Negative Acknowledgement: Negative acknowledgment) is sent back to terminal A, and terminal A retransmits the same data when NAK is received, and repeats this until ACK is received. Protocol.

The number of multiplexes differs between the case where data is transmitted from terminal A to terminal B and the case where ACK or NAK is transmitted from terminal B to terminal A. The multiplexing number in the latter case is always one. The ACK and NAK are stored in the data section 1302. In the former case, the multiplex number is set to 5 at the start of communication. When the number of multiplexes is n, the packet is transmitted without changing the number of multiplexes to n for the preset number of times k, and the number of times ACK is received j is simultaneously counted. When the packet transmission is completed k times, the packet success probability (hereinafter, PSR)
Is calculated by the following formula: PSR = j / k, and is compared with preset threshold values THU and THL. When THU <PSR, n +
1. If THL> PSR, change the multiplex number to n-1. If there is no corresponding multiplex number, ie, n =
THL> PSR, THU <PSR when 1, 5
Is satisfied, the value is continuously used without changing the multiplex number.

In this delay multiplexing system, when the condition of the propagation path is good and little bit error occurs, the number of multiplexes is increased (at this time, the bit rate is increased and the bit error rate is increased), and high-speed transmission is performed. When the state is bad and bit errors frequently occur, the number of multiplexes is reduced (at this time, the bit rate is reduced and the bit error rate is reduced) to suppress the occurrence of errors. In other words, by switching the number of multiplexes (that is, the bit rate) so as to absorb the change in the bit error rate caused by the dynamic change of the propagation path, a signal having a constant quality that satisfies the desired bit error rate can be obtained. High-speed transmission is performed on average while guaranteeing communication.
These properties make it suitable for data communication.

This will be described with reference to FIG. FIG.
Numeral 7 represents the time variation of the propagation loss, bit rate and bit error rate. The horizontal axis is time, and the vertical axis is propagation loss L.
p, bit rate and bit error rate. Generally, a signal is attenuated when the signal propagates through a wireless propagation path, and the propagation loss means the amount of attenuation. The good condition of the radio channel means that the propagation loss is small. Good communication quality means that the bit error rate is low. Since the characteristics of the wireless propagation path change over time, the propagation loss Lp changes as shown by a curve 1701. In the conventional system, in consideration of the occurrence of these fluctuations, the required bit error rate 170 even in the expected worst state (the time zone indicated by 1702) is assumed.
Constant bit rate 17 such that it does not exceed 3
04 was used for transmission. The bit error rate at this time is as shown by a curve 1705, and the propagation path is in the worst state 17.
02 also takes a value lower than the required bit error rate 1703. On the other hand, in this delay multiplexing system, transmission is performed by increasing the bit rate as shown by 1706 so as not to exceed the required bit error rate in a place where the propagation loss is small. The bit error rate at this time is like 1707,
High-speed transmission is performed on average while satisfying the required bit error rate 1703.

[0011]

A system using the above-described delay multiplexing method is not suitable for transmitting information having a constant bit rate and real-time properties such as M-JPEG. In other words, the above system responds to a dynamically changing propagation path by changing the bit rate, but in order to transmit constant bit rate information in real time, the transmission rate is limited to the lowest rate among the rates. This is because the feature of performing high-speed transmission when the propagation path is good cannot be utilized at all. This will be described with reference to FIG. 17. In order to satisfy the required bit error rate 1703 and transmit at a constant bit rate, it is necessary to perform transmission at the bit rate indicated by 1704. Then, it cannot take advantage of its own features.

[0012] From the above, it is required that the above-mentioned method be adapted to transmission of information having a constant bit rate and real-time property. Also, in the data communication, in the above-mentioned method, if the state of the poor propagation path continues for a long time, the low-speed bit rate state for compensating for this will continue for a long time, and the delay time until the data transmission is completed increases. There is. In recent years, in data communications, the content of information to be transmitted has been increasing in large capacity, such as image data, and the interactive information access such as the use of the Internet has been increasing. There is a need for a system, and the above-mentioned system is required to have a property of satisfying a desired bit error rate without lowering the bit rate even if the state of the propagation path continues for a long time.

In order to satisfy these requirements, for example, a method of changing the transmission power without changing the number of multiplexes in the above method can be considered. That is, an operation of increasing the transmission power instead of decreasing the multiplex number is performed. By using this method, it is considered that transmission with a constant quality and a constant bit rate can be performed. However, ISM in Japan
For the obi, RCR-STD which is a Japanese standard
Since the transmission power per unit frequency band is regulated by the above, the transmission power cannot be increased to the regulation value or more, and this method is difficult to realize.

This will be described with reference to FIG. FIG.
8 represents a power density spectrum of the transmission signal. When the transmission power is increased, the shape of the spectrum changes from curve 1801 to curve 1802 and curve 1803,
It exceeds four. The present invention has been made in view of such a problem, and an object of the present invention is to provide a spread spectrum communication apparatus that satisfies required quality while keeping transmission power per unit frequency and bit rate constant. To provide

[0015]

SUMMARY OF THE INVENTION A spread spectrum communication apparatus according to the present invention employs an ARQ system, which multiplexes a signal by directly delaying a spread spectrum signal of a direct spread system by an arbitrary number of chips. Multiplex number control means for changing the number of multiplexed signals; chip rate control means for changing the chip rate of the transmission signal; power control means for changing the transmission power; and the multiplex number control means according to the packet success probability. It comprises a rate control means and a modulation parameter control means for controlling the power control means.

Further, the modulation parameter control means controls the transmission power / chip rate to be constant and the signal multiplexing number × chip rate to be constant, thereby changing the parameter. Since the transmission power per unit frequency does not change, the regulation value of the transmission power can be satisfied. Also, since the bit rate does not change, high-speed transmission can be performed regardless of the propagation path conditions. Also,
The modulation parameter control means reduces the transmission power by controlling the value of the transmission power / chip rate to be equal to or less than a predetermined value and the value of the number of multiplexed signals × the chip rate to be constant. Is possible. Furthermore, by reducing the transmission power, communication can be performed with the minimum required transmission power, and it is possible to reduce extra jamming waves given to the surroundings. That is, the frequency reuse distance is reduced.

Further, the modulation parameter control means sets at least one of a plurality of transmission modes using the number of multiplexes, chip rate, and transmission power as parameters. By determining the transmission mode to be set based on the result of comparing the threshold value and the packet success probability, it is possible to determine the change of the mode finely, thereby using the more optimal transmission mode at that time. Can be. In addition, the modulation parameter control means can quickly converge to an optimal transmission mode by controlling based on a result of comparing a plurality of thresholds with the packet success probability.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. Components having the same functions as those in FIG. 12 are denoted by the same reference numerals, and description thereof will be omitted. FIG. 1 is a block diagram showing a configuration of a spread spectrum communication apparatus according to one embodiment of the present invention. FIG.
Chip rate (data rate)
12 and a variable gain amplifier 8 for changing the transmission power, and a modulation parameter control unit 9 for controlling the number of multiplexed signals and a multiplex number is newly provided instead of the multiplex number control unit 6 in FIG. Prepare for.

In the present communication device, the frequency of the clock generated by the variable rate clock generator 7 can be changed, thereby making it possible to change the chip frequency of the transmission / reception signal. Further, the transmission power can be changed by the variable gain amplifier 8.
Further, the modulation unit 5 can multiplex transmission signals into 1, 2,... 5 multiplexes, and the demodulation unit 1 can receive transmission signals from other terminals thus multiplexed. it can. That is, data can be transmitted and received at a transmission speed of 1, 2,... 5 times. Also, the multiplex number can be changed. The modulation frequency control unit 9 controls the clock frequency, the transmission power, and the multiplex number.

The control of the number of multiplexed received signals is performed as follows. At the time of packet transmission, as shown in FIG. 13, the header part 1301 is transmitted in a single state and the data part 1302 is transmitted in a multiplexed manner.
01 is written. At the time of packet reception, first, the header section 1301 is demodulated in a single manner, the multiplex number in the header section 1301 is read, and the multiplexed data section 1302 is demodulated using this multiplex number.

The control of the clock frequency, the transmission power and the number of multiplexed transmission signals is performed as follows. In the present embodiment,
In order to keep the transmission power and bit rate per unit frequency band constant, the number of multiplexing, chip rate and transmission power are limited to three combinations as shown in FIG. This combination is called a mode. Therefore, multiplexing of three multiplexes and five multiplexes is not performed. The bit rate 201 of the data part and the transmission power per unit frequency 202 are constant in three modes. Since the chip rate 203 increases as the mode increases, the occupied frequency bandwidth required for performing communication also increases accordingly. The transmission power 204 increases as the mode increases. From these facts, it can be understood that the amount of resources necessary for performing communication such as the occupied frequency bandwidth and the transmission power increases as the mode becomes higher. It can be seen that a lower mode may be used to communicate with less resources.

FIG. 3 is a flowchart for explaining the operation of mode determination. First, at the start of communication, the mode is set to 1, and the initial values of the number of transmissions i and the number of ACK receptions j are set (step S1, hereinafter, the letters of the steps are omitted). In S2, the transmission is performed, the number of transmissions i is counted up and received (S3), and the reply content is determined (S3).
4) If NAK, proceed to S13; if ACK, proceed to S13
Go to 5. Regardless of the current mode, the packet is transmitted without changing the mode a preset number of times k (in the case of NAK, the packet is retransmitted (S14)).
The number j of receptions of K is counted (S5). At the time when the transmission of the packet has been completed k times (S6, S13), the packet success probability PSR is calculated by the formula: PSR = j / k (S8, S15), and is compared with the preset threshold values THU and THL (S9, S13). S16).
When THU <PSR, n-1 (S12, S1
9) Change the mode to reduce communication resources and
When> PSR, the mode is changed to n + 1 (S11, S18). When there is no corresponding mode, that is, when n = 1, 3, THU <PSR, THL> P
When the condition of SR is satisfied, the value is continuously used without changing the mode. Then, initial values are set for the number of transmissions i and the number of ACK receptions j (S10, S17). S7
Then, the presence or absence of the next packet is determined. If there is, the flow returns from S15 to S2 to continue, and if there is no next packet, the flow ends.

The THU and THL values are set as follows with reference to FIG. FIG. 4 shows the BER (Bit Er) of each mode.
ror Rate (bit error rate) characteristics. The vertical axis is B
ER and the horizontal axis are the propagation loss Lp. In general, each mode has such characteristics that the bit error rate decreases as the propagation loss decreases. Requested BER (reference numeral 404) from FIG.
In order to obtain a BER characteristic lower than the above, it is understood that it is optimal to use mode 1 in the area 4011, mode 2 in the area 4012, and mode 3 in the area 4013 from the viewpoint of performing communication with less resources.

The threshold is set so that the mode is switched as described above. Here, for example, it is assumed that the required communication quality is BERreq = 1.0 × 10 ⁻⁴ (reference numeral 404) or less. First, the boundary line 40 is located below the intersection of the straight line 404 and the curve 401 and the intersection of the straight line 404 and the curve 402.
Subtract 7 and 408. Next, the intersection 40 of 407 and 402
16 and an intersection 4017 between 408 and 403 is determined. A horizontal line 4015 passes through the lower one of these intersections.
pull. BER indicated by this horizontal line 4015 = 1.0 ×
Let 10 ^-9 be BERsat. Alternatively, with a certain margin, a lower value, for example, BER = 3.0 × 10
^-10 may be BERsat. Propagation loss is boundary value 40
Mode switching frequently occurs when the mode is near 7, 408, and a reduction in communication capacity due to overhead at the time of switching can be prevented by allowing for a margin. From these values, THU and THL can be calculated as follows.

THU = (1-BERsat) ^L THL = (1-BERreq) ^L where L is the total number of bits in the packet. By obtaining THU and THL in this manner, the BER
The condition of req <BER and the condition of THL> PSR are equivalent, and the condition of BERsat> BER and THU <PS
The conditions of R are equivalent, and are associated so that the mode switching condition can be controlled by the level of BER.

By switching from mode 1 to modes 2 and 3 as described above, bit errors can be reduced even if the condition of the propagation path is poor. This will be described with reference to FIG. First, when the mode 1 is used, the propagation loss Lp is 4
If it is smaller than 07, the BER characteristic 401 becomes the required value 404.
Satisfied with no problem. If the condition of the propagation path becomes worse and the propagation loss Lp becomes larger than 407, many bit errors occur,
The BER characteristic 401 exceeds the required value 404. Then TH
The mode is switched to 2 to satisfy L> PSR. As a result, the BER characteristic 402 falls below the required value 404. When the propagation loss Lp becomes larger than 408, T
The mode is switched to 3 in order to satisfy HL> PSR, and the BER characteristic 403 also falls below the required value 404.
As described above, by switching to mode 1 when the propagation loss Lp is in the region of 4011 and switching to mode 2 and 3, respectively, when in the regions 4012 and 4013, communication can be performed with BER characteristics satisfying the required value 404.

Next, a second embodiment of the present invention will be described. FIG. 5 shows the relationship between the mode used in the second embodiment, the number of multiplexes, the chip rate, and the transmission power. In addition to the three modes used in the first embodiment,
Add three modes, Mode 1/4 and Mode 1/8. The chip rate and the multiplex number of these three modes are the same as those of mode 1. Transmission power is mode 1/2, mode 1/4, mode 1 /
8 at 1/2, 1/4, 1/8 of Mode 1 respectively
It has become. That is, these three new modes are power saving. The switching of the six modes is performed in the same manner as in the first embodiment. If THL> PSR, the mode is changed to 1/8 → 1/4 → 1/2 → 1 → 2 → 3. Direction, and when THU <PSR, the direction is changed in the opposite direction (FIG. 3, S9, S11, S12, and S1).
6, S18, S19).

Next, a third embodiment of the present invention will be described. The modes used in the third embodiment are, for example, the same three modes shown in FIG. 2 as in the first embodiment. In the third embodiment, unlike the first embodiment, a threshold value dedicated to each mode is set. That is, THU (M3), T
HL (M3), THU (M2), THL (M2), THU (M1),
Six thresholds of THL (M1) are provided. The subscript (M
x) indicates that the threshold value is dedicated to the mode x. Between these threshold values, there is a relationship of THU (Mx)> THL (Mx): x = 1, 2, 3. These thresholds are set in the same way as in the first embodiment. A specific method will be described below. It is assumed that the required communication quality is BERreq = 10 ⁻⁴ (the straight line 404 in FIG. 4).

First, BERreq (M1), BERreq (M2),
BERsat (M2) and BERsat (M3) are obtained. BERreq
For (M1) and BERreq (M2), BERreq (M1) = BERreq (M2) = BERreq. About BERsat (M2) and BERsat (M3)
The BER values are indicated by horizontal lines 4014 and 4015, respectively. The method of obtaining these horizontal lines is the same as in the first embodiment.

In the first embodiment, the values indicated by the horizontal lines 4015 are used for all the modes, but in the third embodiment, the values indicated by the individual horizontal lines 4014 and 4015 are used for each mode. As in the case of the first embodiment, a value lower than the BER obtained by the above method may be set in consideration of a margin. Based on these BER values, as in the case of the first embodiment, THU (Mx) and THL (Mx)
Ask for.

THU (Mx) = (1-BERsat (Mx)) ^L : x = 2, 3 THL (Mx) = (1-BERreq (Mx)) ^L : x = 1, 2 THU (M1), THL ( For M3), since the PSR to be compared takes a value of 0 ≦ PSR ≦ 1, for example, THU (M1) = 1 and THL (M3) = 0. This is because these values are not particularly meaningful. That is, THU (M1) is a value at the time of transition to a lower mode when mode 1 is used, but since there is no corresponding mode, even if the condition of THU (M1) <PSR is satisfied, mode 1 is used as it is. It is because it becomes. THL
The same can be said for (M3).

The three transmission modes are switched according to the flowchart shown in FIG. 6 using the six thresholds.
Subprograms A and B shown in S100 and S110
7 is shown in FIG. In addition,
S21 to S37 in FIG. 6 correspond to S1 to S7 in FIG. 3. S9, 11, and 12 in FIG. 3 correspond to the subprogram A of S100 in FIG. 6, and S16, 18, and 19 in FIG.
The subprogram B is 0.

In S28 and S35 of FIG. 6, PSR = j / k is calculated as in FIG.
(Same applies to B), and the current mode is M
x (S41), THU (Mx), THL (Mx)
And PSR (S42), and THL (Mx)> PS
If R, switch to high mode (S43), THU (Mx)
In the case of <PSR, the mode is switched to the low mode (S44), and in other cases, the subprogram A is terminated without any change. In the first embodiment, the same threshold value is always used as the threshold value for comparison with the PSR (see S9 and S16 in FIG. 3). Third
In the embodiment, as shown in S42 of FIG. 7, a threshold dedicated to the currently used mode is used.

Next, a fourth embodiment of the present invention will be described (see flowcharts in FIGS. 6 and 10). In the first and second embodiments, two thresholds THU and THL are set. In the fourth embodiment, four thresholds dedicated to each mode are set for each mode. As for the modes, the same six as shown in FIG. 5 for the second embodiment are provided. Eventually, the following 24 thresholds are provided.

THU2 (M3), THU1 (M3), THL1 (M3), THL2 (M3), THU2 (M2), THU1 (M2), THL1 (M2), THL2 (M2), THU2 (M1), THU1 ( M1), THL1 (M1), THL2 (M1), THU2 (M1 / 2), THU1 (M1 / 2), THL1 (M1 / 2), THL2 (M1 / 2), THU2 (M1 / 4), THU1 ( M1 / 4), THL1 (M1 / 4), THL2 (M1 / 4), THU2 (M1 / 8), THU1 (M1 / 8), THL1 (M1 / 8), THL2 (M1 / 8), Subscript ( Mx) indicates that the threshold value is dedicated to mode x. Between these thresholds, THL2 (Mx) <THL1 (Mx) <THU1 (Mx) <TH
U2 (Mx) x = 1/8, 1/4, 1/2, 1, 2, 3.

These thresholds are set in the same way as in the third embodiment. A specific method will be described below. The communication quality required here is BERreq (the horizontal line 8 in FIG. 8).
04) Assume that: Fig. 8 shows the BER of each mode.
This corresponds to the role of FIG. 4 in the first and third embodiments. First, referring to FIG. 8, BER2d (M
x), BER1d (Mx), BER1u (Mx), BER2u (Mx)
For x = 1/8, 1/4, 1/2, 1, 2, and 3.
These values are represented by B in the table of FIG.
It becomes the value of ER. The method of creating FIG. 8 is the same as the method of creating FIG. 4 in the first and third embodiments.

In the table of FIG. 9, the threshold value corresponding to the column of = 0 or = 1 is 0 or 1. This reason is the same as that in the third embodiment, THU (M1) = 1 and THL (M3) = 0. As in the case of the first and third embodiments, taking into account the margin, B
Low values for ER2d (Mx), BER1d (Mx), BER
2u (Mx) may be set to a high value. These BEs
Based on the value of R, THU2 (Mx) = (1-BER2d (Mx)) ^L THU1 (Mx) = (1-BER1d (Mx)) ^L THL1 ( Mx) = (1-BER1u (Mx)) ^L THL2 (Mx) = (1-BER2u (Mx)) ^L 24 threshold values are obtained as follows. The mode is switched using four thresholds for each mode. A specific switching process is shown in the flowchart of FIG. 6, and a detailed flowchart of the sub-programs A and B in FIG. 6 is shown in FIG.

In S28 and S35 of FIG. 6, PSR = j / k is calculated as in FIG.
(Same applies to B), and the current mode is M
x (S51), PSR and THU2 (Mx), T
HU1 (Mx), THL1 (Mx), and THL2 (Mx) are compared (S52), and if THL2 (Mx) ≧ PSR, the transmission mode is switched to a higher-level transmission mode by two levels (S53).
If (Mx)>PSR> THL2 (Mx), the mode is switched to the transmission mode one level higher (S54), and THU1 (Mx) <P
If SR <THU2 (Mx), the mode is switched to the transmission mode one level lower (S55), and THU2 (Mx) ≦ P
In the case of SR, the transmission mode is switched to the transmission mode two levels lower (S
56) In other cases, the subprogram A is terminated without any change.

Here, there are an upper transmission mode and a lower transmission mode.
2, 1, 1/2, 1/4, 1/8. Switching to the mode two levels higher when using mode 1 means switching to mode 3. In the third embodiment, the number of thresholds to be compared with the PSR is two, and the mode transition is performed one level at a time.
The number of thresholds to be compared with R is four, and two at a time depending on conditions.
It is possible to perform the transition of the mode of the level.

As described above, the spread spectrum communication apparatus of the present invention is different from the conventional delay multiplexing method using direct spread spectrum as shown in FIG. As described above, the variable gain amplifier 8 for changing the transmission power and the variable rate clock generator 7 for changing the chip rate are provided, and the modulation parameter control unit 6 for controlling the number of multiplexes and the multiplex number control unit shown in FIG. 6 is newly provided instead of 6, and not only the multiplex number but also the transmission power and the chip rate are changed by using these. That is, when the state of the propagation path is poor and many bit errors occur, the transmission power is increased, the chip rate is increased, the number of multiplexes is reduced, and when the propagation path is good, the opposite operation is performed. At this time, the shape of the spectrum of the transmission signal is respectively represented by curves 1101 to 1102, 1103, and 1103 in FIG.
When the condition is good, the opposite is true, and the value can be changed without exceeding the regulation value 1104. By these operations,
It is also possible to perform high-speed transmission as shown by 1708 in FIG. 17 while maintaining desired transmission quality while keeping transmission power and bit rate per unit frequency band constant.

[0041]

As described in detail above, according to the present invention, even if the condition of the propagation path is poor, bit errors can be reduced, and the transmission power and bit rate per unit frequency band can be kept constant. It is also possible to perform high-speed transmission while satisfying desired communication quality while keeping the same.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a spread spectrum communication apparatus according to an embodiment of the present invention.

FIG. 2 is a table showing a relationship among modes, a multiplex number, a chip rate, and transmission power in the first and third embodiments.

FIG. 3 is a flowchart showing a mode determination operation in the first and second embodiments.

FIG. 4 is a graph showing a relationship between a propagation loss and a BER in each mode in the first and third embodiments.

FIG. 5 is a table showing a relationship among modes, multiplexing numbers, chip rates, and transmission power in the second and fourth embodiments.

FIG. 6 is a flowchart showing a mode determination operation in the third and fourth embodiments.

FIG. 7 is a flowchart illustrating details of a subprogram according to the third embodiment.

FIG. 8 shows propagation loss and B of each mode in the fourth embodiment.
7 is a graph showing a relationship with ER.

FIG. 9 is a table showing a relationship between a BER value and a mode x shown in FIG. 8;

FIG. 10 is a flowchart illustrating details of a subprogram according to a fourth embodiment.

FIG. 11 is a diagram showing a transmission power density spectrum according to the embodiment of the present invention.

FIG. 12 is a system configuration diagram of a delay multiplexing method of a conventional device.

FIG. 13 is a diagram showing a packet format of a conventional device.

FIG. 14 is a block diagram of a baseband signal processing part of a modulation unit of the conventional device.

FIG. 15 is a diagram showing a signal configuration at the time of 5-multiplexing in FIG. 14;

FIG. 16 is a diagram showing a signal configuration at the time of multiplexing in FIG. 14;

FIG. 17 shows a temporal variation of a propagation loss in a wireless propagation path,
7 is a graph showing a temporal variation of a bit rate and a bit error rate in the communication device of the related art and the present invention.

FIG. 18 is a diagram showing a transmission power density spectrum of a system that cannot be realized due to regulation.

[Explanation of symbols]

1 Demodulation unit 2 Receiving-side data processing unit 3 Upper layer 4 Sender data processing unit 5 Modulation section 6 Modulation parameter control unit 7 Variable rate clock generator 8 Variable gain amplifier 9 Modulation parameter control unit

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) H04J 13/00-13/06 H04B 1/69-1/713 H04L 1/00 H04L 1/18

Claims (4)

(57) [Claims] 1. A delay multiplex spread spectrum communication apparatus which is an ARQ method and multiplexes a signal by time-delaying a spread spectrum signal of a direct spread method by an arbitrary number of chips, wherein the multiplexing means changes the number of multiplexed transmission signals. Number control means, chip rate control means for changing a chip rate of a transmission signal, power control means for changing transmission power, the multiplex number control means, chip rate control means, and power control according to a packet success probability. and a modulation parameter control means for controlling the means, the modulation parameter control means, the transmission power / Chippure
Signal value is constant and the number of multiplexed signals x chip rate
A spread spectrum communication device , wherein the value is controlled to be constant . 2. An ARQ scheme, which is a direct-spread scheme.
Delays the spread spectrum signal by an arbitrary number of chips.
Number multiplexing means for changing the number of multiplexed transmission signals, and chip rate control for changing the chip rate of the transmission signal.
Means, power control means for changing transmission power, and the multiplex number control means according to the packet success probability, chip
Rate control means and a modulation pattern for controlling the power control means.
Comprising a parameter control means, said modulation parameter control means includes a feature that the value of the transmission power / chip rate becomes less than a predetermined value, and controls so that the value of the signal multiplexing × chip rate is constant You
Spread spectrum communication equipment. 3. The modulation parameter control means sets at least one of a plurality of transmission modes using the number of multiplexes, chip rate, and transmission power as parameters. 3. The spread spectrum communication apparatus according to claim 1, wherein a transmission mode to be set is determined based on a result of comparing a threshold with the packet success probability. Wherein said modulation parameter control means, spread spectrum communication device according to any one of claims 1 to 3, characterized in that controlled by the result of comparing the packet success probability with a plurality of thresholds.