TWI426791B - Interrupt capacity calculation device and method - Google Patents

Description

Interrupt capacity calculation device and method

The present invention relates to an interrupt capacity calculation device and method, and more particularly to an interrupt capacity calculation device and method modeled on any Nakagami-m attenuation channel.

Referring to Figure 1, a transmission system 900 employing a Transmit Antenna Selection/Maximal-Ratio Combining (TAS/MRC) architecture is shown. Under such an architecture, the receiving end Rx will first perform channel estimation to know which transmitting end antenna 93 has better channel quality for the plurality of antennas 94 of the receiving end Rx. Then, the transmitting end Tx transmits a signal with the preferred antenna 93, and the receiving end Rx weights the signals received by all the antennas 94 to optimize the overall transceiving performance of the transmitting system 900.

X. Zhang et al., "Outage capacity analysis of multiuser diversity in MIMO antenna selection systems," IEEE PIMRC' 2007, pp. 1-5, Sept. 2007 , simulated with the Rayleigh channel of Figure 2. The interrupt capacity of the TAS/MRC architecture is used as a basis for evaluating the performance of the transceiver.

However, the Rayleigh channel is only suitable for describing the fading phenomenon caused by the multipath propagation alone, and it is not suitable for the shadowing, fading or other interference conditions that the simulated metropolitan area transmission environment may face. Therefore, when using the metropolitan area as the evaluation background, the simulation data of the interrupt capacity obtained according to the Rayleigh channel is not objective.

Therefore, the object of the present invention is to provide an interrupt capacity calculation device and method, and to calculate an interrupt capacity of a transmission system by using any Nakagami- m attenuation channel that can closely match the transmission environment of the metropolitan area. Help objectively evaluate the performance of the receiving and receiving system.

Accordingly, the interrupt capacity calculation apparatus of the present invention is suitable for analyzing a transmission system including a transmitting antenna and a receiving antenna, and defining a transmitting antenna and the receiving antenna using a mid-up (Nakagami) channel model. In the inter-channel, the interrupt capacity calculation device comprises: a signal-to-noise ratio operation module, and calculating a signal for the signal received by the receiving antenna according to an attenuation index and an average signal-to-noise ratio of the upper-middle channel model Ratio-of-experience value and a signal-to-interference ratio variation; a capacity calculation module calculates an interrupt capacity by using the signal-to-noise ratio expected value and the signal-to-noise ratio variation on a transmission interruption rate; and an output module, According to the average signal-to-noise ratio and the interrupt capacity, information about the performance of the transmission and reception of the transmission system is provided.

The interrupt capacity calculation method of the present invention is suitable for analyzing a transmission system, the transmission system includes a transmitting antenna and a receiving antenna, and uses a mid-up (Nakagami) channel model to define the transmitting antenna and the receiving antenna. The channel, the interrupt capacity calculation method comprises the following steps: using a signal-to-noise ratio operation module, calculating a signal for the receiving antenna according to an attenuation index and an average signal-to-noise ratio of the upper-middle channel The ratio of the odds ratio and the variance of the signal ratio; using a capacity calculation module to calculate an interrupt capacity by using the ratio of the signal to noise ratio and the variance of the ratio of the signal to the interference ratio; and using an output The module provides information on the performance of the transmission and reception of the transmission system according to the average signal-to-noise ratio and the interrupt capacity.

The above and other technical contents, features and advantages of the present invention will be apparent from the following detailed description of the preferred embodiments.

Principle derivation and introduction

The transmission system 100 of FIG. 3 employs a transmission selective diversity/receive maximum ratio combining (TAS/MRC) architecture including a transmitter 1 and a receiver 2. The transmitter 1 includes a diversity unit 11 and L _T (L _T >1) transmit antennas 12. The receiver 2 includes L _R (L _R >1) receive antennas 22, a synthesizing unit 21, and a channel estimator 23. . For convenience of illustration, FIG. 3 takes L _T =3 and L _R =2 as an example.

In such a TAS/MRC architecture, there are L _T × L _R possible channels, each channel being defined by one of the transmit antennas 12 and one of the receive antennas 22. When the channel estimator 23 estimates the transmission quality of each channel, it will notify the diversity unit 11 which transmission antenna 12 corresponds to the channel transmission quality. Next, the diversity unit 11 transmits a signal to be transmitted to the transmitting antenna 12 having the better channel transmission quality for transmission. The L _R receiving antennas 22 receive the signals and transmit them to the synthesizing unit 21, and the synthesizing unit 21 uses the channel transmission quality of the L _R receiving antennas 22 corresponding to the better channel quality transmitting antennas 12, The weighting calculation is performed based on the signals received by the L _R receiving antennas 22 to obtain a composite signal.

For example, Z. Chen et al. in "Analysis of transmit antenna selection/maximal-ratio combining in Rayleigh fading channels," IEEE Trans . Veh. Technol., vol. 54, no. 4, pp. 1312 - 1321 , July 2005 . Description, assuming that the channel model is a Nakagami channel with a fading index = m as shown in Fig. 4, the probability distribution of the signal-to-noise ratio (SNR) of the synthesized signal can be a signal-to-noise ratio. Q is expressed as a probability density function of the variable, as in equation (1).

among them, Is the average signal-to-noise ratio of the signal to be transmitted in a single channel, , z is any positive number, and It is an incomplete gamma function, reference may ISGradshteyn et al "Table of Integrals, Series, and Products" 5 th ed., Academic Press, New York, 1994 book of Equation (8.350.1).

Note that in Figure 4, the attenuation index m of the Nakagami channel can be any positive number, and different indices can correspond to different degrees of channel attenuation. Compared with the Rayleigh distribution of Figure 2, only the case of m=1 can be described. The Nakagami channel is more likely to describe the communication environment of the metropolitan area.

Further application of the book contained ISGradshteyn equation (8.352.1), (8.351.2), (9.14.1) and (0.314), may be Rewrite the formula (2) that satisfies "m≧1/2" or rewrite it to the equation (3) that satisfies "m is a positive integer".

(2)

among them,

Therefore, the signal-to-noise ratio expectation value μ _Q and the noise ratio variance σ _Q ² can be estimated by dividing into "m≧1/2" and "m is a positive integer".

When "m≧1/2",

(5)

And when "m is a positive integer",

According to X. Zhang et al., "Outage capacity analysis of multiuser diversity in MIMO antenna selection systems," IEEE PIMRC' 2007, pp. 1-5, Sept. 2007 , in the TAS/MRC architecture, if the composite signal The signal-to-noise ratio = Q, the signal-to-noise ratio expected value = μ _Q , and the signal-to-noise ratio variation = σ _Q ² , then the channel capacity C ( Q ) can be "approximate" to equation (8), and the channel capacity expectation value μ _C can be " The approximation is expressed by equation (9), and the channel capacity variation number σ _C ² can be "approximate" to equation (10).

Moreover, if the number of samples of the channel capacity is sufficient, it can be expected according to the central limit theorem that the probability density function value of the aggregate channel capacity can approach a Gaussian distribution. When the attenuation index is m=3, the number of transmitting antennas L _T =3, and the number of receiving antennas L _R =2, the Gaussian distribution will be as shown in Fig. 5; and in this figure, the probability density function value of the channel capacity is in the form of a straight strip. Draw, the ideal Gaussian distribution is drawn as a solid curve.

Therefore, a probability density function with the channel capacity C ( Q ) as a variable can be expressed as Equation (11).

Furthermore , the document proposed by X. Zhang further describes the maximum channel capacity C _B that the transmission system 100 can support under the premise that the transmission achievement rate (100-B)% (ie, the transmission interruption rate is B%). The "approximate" is as follows:

Where erfc ^-1 (.) is the inverse of the error function erfc(.). In particular, the definition of the transmission achievement rate is the ratio of the "sum of the probability density function values of the channel capacities 0 to C _B " to the "sum of the probability density function values of the channel capacities 0 to 」".

Finally, by substituting the equations (4)~(7) into the equation (12), the transmission system 100 using the TAS/MRC architecture can be obtained with the Nakagami channel as the model. Channel capacity, which is the interrupt capacity.

Preferred embodiment

Referring back to FIG. 3, a preferred embodiment of the interrupt capacity calculation device 300 of the present invention is suitable for analyzing the composite signal combined by the synthesis unit 21, and preferably this example is applied to a Nakagami channel model using attenuation index = m. The system 100 is transmitted, and the L _T × L _R channels have the same average signal-to-noise ratio .

Referring to FIG. 6, on the basis of the formulas (4) to (7) and (12), the interrupt capacity calculation device 300 includes a signal-to-noise ratio operation module 3, a capacity calculation module 4, and a circuit that are sequentially electrically connected. Output module 5. The signal-to-noise ratio operation module 3 utilizes the average signal-to-noise ratio of each channel For the synthesized signal, a signal-to-noise ratio expectation value and a signal-to-noise ratio variation satisfying "m≧1/2" or satisfying "m is a positive integer" are calculated. Then, the capacity calculation module 4 calculates an interrupt capacity by using the signal-to-noise ratio expected value and the signal-to-noise ratio variation based on a specific transmission interruption rate B%. Finally, the output module 5 is based on the average signal-to-noise ratio of each channel. And the interrupt capacity is used to evaluate the performance of the transmission and reception system 100.

The preferred embodiment of the interrupt capacity calculation method of the present invention performed by the interrupt capacity computing device 300 includes the following steps of FIG. 7:

Step 71: The signal-to-noise ratio operation module 3 sets an average signal-to-noise ratio for each possible channel. Value, and the average signal-to-noise ratio of all channels All the same.

Step 72: The signal-to-noise ratio operation module 3 utilizes the average signal-to-noise ratio of each channel. For the synthesized signal, a signal-to-noise ratio expected value μ _Q and a signal-to-noise ratio variation σ _Q ² satisfying "m≧1/2" or satisfying "m is a positive integer" are calculated.

In detail, the signal-to-noise ratio operation module 3 first determines whether the attenuation index m satisfies "m is a positive integer". When the determination is established, the signal-to-noise ratio calculation module 3 calculates the signal-to-noise ratio expectation value μ _Q satisfying "m is a positive integer" for the synthesized signal based on the equation (6), and calculates the equation (7) based on the equation (7). Corresponding signal-to-noise ratio variation σ _Q ² .

When the determination is not established, the signal-to-noise ratio calculation module 3 calculates the signal-to-noise ratio expected value μ _Q satisfying "m≧1/2" for the synthesized signal based on the equation (4), and is based on the equation (5). The corresponding signal-to-noise ratio variation σ _Q ² is calculated.

It can be observed from equations (4) to (7) that the signal-to-noise ratio operation module 3 mainly utilizes the average signal-to-noise ratio. The attenuation index m, the number of transmitting antennas L _{T ,} and the number of receiving antennas L _R are calculated.

Of course, in another embodiment, the signal-to-noise ratio operation module 3 may first determine whether the attenuation index m is 1/2 or not, so as to calculate according to the equations (4) and (5) when the judgment is established.

Step 73: The capacity calculation module 4 calculates the set value of the signal-to-noise ratio expected value μ _Q and the signal-to-noise ratio variation σ _Q ² according to the equation (12) based on the specific transmission interruption rate B%. Average signal to noise ratio Corresponding interrupt capacity C _B .

Step 74: The output module 5 determines whether to enable the signal-to-noise ratio operation module 3 to set another average signal-to-noise ratio according to a capacity calculation instruction. Value for the capacity calculation module 4 to calculate the other average signal to noise ratio Corresponding interrupt capacity C _B .

If yes, skip back to step 71, otherwise proceed to step 75.

Step 75: The output module 5 has an average signal-to-noise ratio according to each setting. Corresponding interrupt capacity C _B provides information on the performance of the transmission and reception system 100.

Taking the simulation diagram of FIG. 8 as an example, it represents the ideal value of the interrupt capacity C _B corresponding to 5% of the transmission interruption rate when L _T =3, L _R =2, and m=3. And △ when _{L T = 3, L R =} 2, m = ideal value 0.8 to □ represents _{L T 2, L R = 2} , m = ideal value 3 is = to ○ represents L _T = 2 The ideal value when L _R = 2 and m = 0.8. Further, the interruption capacity C _B "after approximation" in this example is indicated by *.

Through Figure 8, it can be observed that the approximate analog value of this example is almost close to the ideal value, and the average signal-to-noise ratio of all settings is aggregated. Corresponding interrupt capacity C _B , it can be observed that the interrupt capacity C _B will increase with the increase of the average signal-to-noise ratio of each channel, which implies that the transmission system 100 can tolerate higher transmission capacity and has better transmission and reception. which performed.

Finally, it is worth noting that, in this example, regardless of whether the attenuation index m of the Nakagami channel is any positive integer or any positive value satisfying "m≧1/2", the signal-to-noise ratio operation module 3 can correspondingly obtain the signal. The odds ratio expectation value μ _Q and the signal-to-noise ratio variation σ _Q ² , so the simulation is not limited, and the channel of any attenuation degree in the metropolitan area can be applied.

It should be noted that the transmitter 1 of FIG. 3 may also have only one transmitting antenna 12, in which case the diversity unit 11 is omitted, and the signal to be transmitted is sent by the unique transmitting antenna 12.

Moreover, as far as the receiver 2 is concerned, there may be only one number L _{R of} receiving antennas 22, so that the combining unit 21 of FIG. 3 may omit the synthesizing unit 21, and the interrupt capacity calculating device 300 will directly analyze the unique receiving antenna. 22 received signals.

In summary, in this embodiment, the interrupt capacity C _{B of the} specific transmission interruption rate B% can be calculated by first calculating the signal-to-noise ratio expected value μ _Q and the signal-to-noise ratio variation σ _Q ² applicable to the Nakagami channel. The transmission and reception performance of the transmission system 100 in the metropolitan area is more easily and accurately predicted, so that the object of the present invention can be achieved.

The above is only the preferred embodiment of the present invention, and the scope of the invention is not limited thereto, that is, the simple equivalent changes and modifications made by the scope of the invention and the description of the invention are All remain within the scope of the invention patent.

100. . . Collection system

1. . . Transmitter

11. . . Diversity unit

12. . . Transmitting antenna

2. . . receiver

twenty one. . . Synthetic unit

twenty two. . . Receive antenna

twenty three. . . Channel estimator

300. . . Interrupt capacity calculation device

3. . . Signal ratio module

4. . . Capacity calculation module

5. . . Output module

71. . . Steps to set the average signal to noise ratio

72. . . Steps to calculate expected and variance

73. . . Steps to calculate the interrupt capacity

74. . . Steps to decide whether to calculate another interrupt capacity

75. . . Provide steps to send and receive performance

Figure 1 is a block diagram illustrating a conventional collection system;

Figure 2 is a schematic diagram illustrating the Rayleigh distribution;

3 is a block diagram showing a transmission system to which the preferred embodiment of the interrupt capacity calculation device of the present invention is applied;

Figure 4 is a schematic view showing the distribution of the upper middle type;

Figure 5 is a schematic diagram showing that the probability density function values of the plurality of channel capacities will approach a Gaussian distribution;

Figure 6 is a block diagram showing a preferred embodiment of the interrupt capacity calculating device of the present invention;

Figure 7 is a flow chart showing a preferred embodiment of the method for calculating the interrupt capacity of the present invention;

Figure 8 is a schematic diagram showing the relative relationship of the channel average signal-to-noise ratio to the interrupt capacity.

300. . . Interrupt capacity calculation device

3. . . Signal ratio module

4. . . Capacity calculation module

5. . . Output module

Claims (8)

An interrupt capacity calculation device is suitable for analyzing a transmission system, the transmission system comprising a transmitting antenna and a receiving antenna, and using a mid-up (Nakagami) channel model to define a channel between the transmitting antenna and the receiving antenna The interrupt capacity calculation device includes: a signal-to-noise ratio operation module, and calculating a signal-to-noise ratio expectation value for the signal received by the receiving antenna according to an attenuation index and an average signal-to-noise ratio of the upper-middle channel model a noise ratio variation module; a capacity calculation module, based on a transmission interruption rate, using the signal-to-noise ratio expected value and the signal-to-noise ratio variation to calculate an interruption capacity; and an output module, according to the average The signal-to-noise ratio and the interrupt capacity provide information on the performance of the transmission and reception of the transmission system; wherein the signal-to-noise ratio operation module further receives the reception antenna according to another average signal-to-noise ratio of the upper-middle channel model The obtained signal calculates a corresponding signal-to-noise ratio expected value and a signal-to-noise ratio variation, so that the capacity calculation module calculates an interrupt capacity related to the other average signal-to-noise ratio, and the output module according to the The two average signal-to-noise ratios and the corresponding two interrupt capacities provide information on the performance of the transmission and reception of the transmission system. According to the interrupt capacity calculation device of claim 1, the transmission system further includes another transmitting antenna, another receiving antenna, and a synthesizing unit, and uses the mid-up channel model to define each transmitting antenna. And a channel between each receiving antenna, and is signaled by one of the transmitting antennas according to the transmission quality of the corresponding channel of the two transmitting antennas, and And obtaining, by the synthesizing unit, a composite signal according to the signals received by the receiving antennas, wherein the signal-to-noise ratio computing module is based on the attenuation index and the average signal-to-noise ratio of the upper-middle channel model, and according to the transmitting The number of antennas and the number of the receiving antennas are used to calculate the signal to noise ratio expected value and the signal to noise ratio variation for the composite signal. The interrupt capacity calculation device according to claim 2, wherein when the attenuation index of the upper-middle channel model is m≧1/2, the signal-to-noise ratio operation module according to the attenuation index m and the average signal Miscellaneous ratio And calculating the signal-to-noise ratio expectation value μ _Q and the signal-to-noise ratio variation σ _Q ² according to the number of transmission antennas L _T and the number of the receiving antennas L _R , as follows: among them, , z is any positive number, The interrupt capacity calculation device according to the second aspect of the patent application, wherein, when the attenuation index m of the upper middle channel model is a positive integer, the signal-to-noise ratio operation module according to the attenuation index m and the average noise ratio And calculating the signal-to-noise ratio expectation value μ _Q and the signal-to-noise ratio variation σ _Q ² according to the number of transmission antennas L _T and the number of the receiving antennas L _R , as follows: among them, , z is any positive number, An interrupt capacity calculation method is suitable for analyzing a transmission system, the transmission system includes a transmitting antenna and a receiving antenna, and uses a mid-up (Nakagami) channel model to define a channel between the transmitting antenna and the receiving antenna The interrupt capacity calculation method includes the following steps: calculating a signal-to-noise ratio for a signal received by the receiving antenna according to an attenuation index and an average signal-to-noise ratio of the upper-middle channel by using a signal-to-noise ratio operation module Expectation value and one-to-one ratio variation; using a capacity calculation module, based on a transmission interruption rate, Using the signal-to-noise ratio expected value and the signal-to-noise ratio variation, calculating an interrupt capacity; using an output module to provide information on the performance of the transceiver system according to the average signal-to-noise ratio and the interrupt capacity; The ratio operation module further calculates a corresponding signal-to-noise ratio expectation value and a signal-to-noise ratio variance for the signal received by the receiving antenna according to another average signal-to-noise ratio of the upper-middle channel model; Calculating an interrupt capacity related to the other average signal-to-noise ratio; and using the output module to provide information on the performance of the transmission and reception of the transmission system according to the two average signal-to-noise ratios and the corresponding two interrupt capacities. According to the interrupt capacity calculation method described in claim 5, the transmission system further includes another transmitting antenna, another receiving antenna, and a synthesizing unit, and uses the mid-upper channel model to define each transmitting antenna. And a channel between each receiving antenna, and a signal is sent by one of the transmitting antennas according to the transmission quality of the corresponding channel of the two transmitting antennas, and a composite signal is obtained by the synthesizing unit according to the signals received by the receiving antennas The signal-to-noise ratio computing module calculates the signal-to-noise ratio for the composite signal according to the attenuation index and the average signal-to-noise ratio of the upper-middle channel and according to the number of the transmitting antennas and the number of the receiving antennas. Expected value and the number of variances. According to the interrupt capacity calculation method described in claim 6, wherein, when the attenuation index of the upper-middle channel model is m≧1/2, the signal-to-noise ratio operation module according to the attenuation index m and the average signal Miscellaneous ratio And calculating the signal-to-noise ratio expectation value μ _Q and the signal-to-noise ratio variation σ _Q ² according to the number of transmission antennas L _T and the number of the receiving antennas L _R , as follows: among them, , z is any positive number, According to the interrupt capacity calculation method described in claim 6, wherein when the attenuation index m of the upper-middle channel model is a positive integer, the signal-to-noise ratio operation module according to the attenuation index m and the average interference ratio And calculating the signal-to-noise ratio expectation value μ _Q and the signal-to-noise ratio variation σ _Q ² according to the number of transmission antennas L _T and the number of the receiving antennas L _R , as follows: among them, , z is any positive number,