spectrum

each otherTo make better use of the system bandwidth, the sub-carrier can be spaced as close as possible.Figure 12: Close to FDM, in practice, considering the hardware implementation, demodulation of the first signal, it is difficult to completely remove the impact of the second signal (the implementation of the circuit after all, can not be as neat as scissors cutting paper), the two signals may have caused interference with each otherCan you come closer? OK. This is the origin of OFDM, ah, ne

addition, the distribution of band will affect the system compatibility. To meet the needs of broadband access network business development in different regions and different application scenarios, the maximum bandwidth of VDSL2 can reach 30 MHz. For bandwidth below 12 MHz, the Plan997 and Plan998 bandwidths of VDSL are adopted. Among them, Plan997 is suitable for the application mode of Bidirectional symmetric rate of medium and short distance, while Plan998 is suitable for the application mod

Cognitive Radio (CR) technology effectively relieves the conflict between the lack of spectrum resources and the increasing demand for wireless access through secondary exploitation of the authorized spectrum, people are getting more and more attention. To enable CR users to use spectrum holes and avoid harmful interference to authorized users, the Media Access C

difficult to completely remove the impact of the second signal (the implementation of the circuit after all, can not be as neat as scissors cutting paper), the two signals may have caused interference with each otherCan you come closer? OK. This is the origin of OFDM, ah, nearly equal to the Nyquist bandwidth (detailed later), so that the frequency band utilization reached the theoretical maximum value.Figure 13: Continue closer, the interval frequency is orthogonal to each other, so the

Cognitive radio (CR) technology has been paid more and more attention by the way of "two utilization" of the authorized spectrum, which effectively relieves the contradiction between the lack of spectrum resources and the increasing demand for wireless access. In order to realize CR users ' use of spectrum holes while avoiding harmful interference to authorized

positive cosine wave consisting of positive and negative frequencies, which can be expressed in the form of complex numbers.We know that in the real Fourier transform, its spectrum is 0 ~π (0 ~ n/2), but cannot represent the spectrum of-π~ 0, it can be foreseen that if the positive cosine is expressed in the plural form, it can be included in the negative frequency.Second, the variables before and after th

consumption accounts for 59% of Verizon Wireless's total network traffic. It is expected that with the increasing popularity of 4G services, the promotion of traffic consumption will become more obvious. At the same time, the traffic characteristics of the mobile Internet era also show obvious asymmetry. According to the actual measurement data of some operators in the European, American, and Japanese markets, the downstream data traffic is generally 4 ~ of the upstream traffic ~ 9 times. It ca

Understanding Discrete Fourier Transformation (4) ------ complex form discrete Fourier transformation uses the complex method very cleverly, making the Fourier transformation more natural and concise, it does not simply use the replacement method to use the plural, but analyzes the problem from the perspective of the plural, which is totally different from the real DFT. I, Returns the positive cosine of a number.Through the Euler's equation, the positive cosine function can be expressed as a com

Understanding of discrete Fourier transform (d)------complex form of discrete Fourier transform the discrete Fourier transform is very ingenious to use the complex method, making Fourier transform transformation more natural and concise, it is not simply to use the replacement method to use the complex Number, but to analyze the problem completely from the plural point of view, which is completely different from the real DFT.One, to represent a positive cosine function as a plural formThe positi

Understanding of discrete Fourier transform (d)------complex form of discrete Fourier transform the discrete Fourier transform is very ingenious to use the complex method, making Fourier transform transformation more natural and concise, it is not simply to use the replacement method to use the complex Number, but to analyze the problem completely from the plural point of view, which is completely different from the real DFT.One, to represent a positive cosine function as a plural formThe positi

plural number, which is totally different from the real DFT.1. Represent the positive cosine function in the form of a plural number. through the Euler's equation, the positive cosine function can be expressed as a complex number: CoS (X) = 1/2 e j (-x) + 1/2 ejx sin (x) = J (1/2 e j (-x)-1/2 ejx) From this equation, we can see that after the positive cosine function is expressed as a complex number, they become a positive cosine wave composed of positive and negative frequencies. On the c

Now, wireless designers are faced with the arduous task of designing world-class products. Many wireless technical standards define the technical indicators of power, but ignore the specific steps of Power Measurement. Therefore, designers often encounter Errors During measurement. Because the ofdm rf waveforms used in IEEE 802.16 are complex, more errors occur when measuring mobile WiMAX signals. This article describes important information about WiMAX channel power measurement. These basic pri

Fourier series are used in periodic signals, while Fourier transforms are applied in periodic and aperiodic signals. It is also possible to cycle the signal with Fourier series, while the energy signal uses the Fourier transform (because the energy signal is non-periodic except for all 0). Fourier transform/progression is just an analytical tool that is used to analyzeSpectrum of. Spectrum generally refers to the frequency content of the signal,

: Fourier series sawtooth wave circles animation.gif If you click out, don't be turned off and run on Wiki. Where are the articles written on Wiki. After introducing the basic component units in the frequency field, we can take a look at a Rectangular Wave in the frequency field: What is this strange thing? This is what the Rectangular Wave looks like in the frequency field. Isn't it completely recognizable? Textbooks are generally given here and left with endless fantasies and endless sputati

new capabilities (such as implementing new monitoring, increasing the flexibility of existing devices, and reducing operation and process management costs) into the industries they serve. In turn, many different types of wireless technologies and applications are rapidly emerging to meet this growing demand. It should be emphasized that there are some unique challenges in the industrial field, but many traditional wireless technologies are not designed specifically to address these challenges.

are three: IMT-2000 cdma-ds (IMT-2000 Direct spread-spectrum CDMA), that is, WCDMA, it can be in a bandwidth of up to 5MHz in the frequency of direct spread of the signal IMT-2000CDMA-MC (IMT-2000 Multicarrier CDMA), that is, CDMA2000, a technology proposed by the United States, It is a broadband system consisting of one or more 1.25MHz narrowband direct spread spectrum systems, and TD-SCDMA (Time Division

frequency, the frequency domain system is made up of spanned coordinate systems, where and as (frequency) variables. The spatial domain is the coordinate system spanned by f (x, y) . The spectral components of the spectrum system in the four corners of the spectrum graph are obtained by 0. The discrete Fourier inverse transformation is given by the following formula:So that R and I represent the real and r

China's LTE commercialization is approaching, and the industry's attention to the subsequent evolution of LTE has reached a new peak. Compared with 3G, LTE significantly improves the spectrum efficiency. However, the industry has not stopped. A few years ago, 3GPP began to research and develop the LTE-Advanced standard, and a series of technologies that can effectively improve the performance of existing LTE Networks emerged. Among them, the two most

transformation. We can get the Fourier transformation of the signal into a pulse function (while the discrete signal is a continuous pulse, because the Fourier series coefficient of the discrete signal is cyclical, but continuous is not of this nature ); At last, continuous signals can only move the spectrum to a finite band, while discrete signals will continue to shift (however, in fact, the spectrum is

1: What are the characteristics of TDD technology? L Time Division Duplex (TDD): distinguishes uplink and downlink based on different time slots P advantages N when the upstream and downstream services are asymmetrical, different quantities of time slots can be flexibly allocated to the upstream and downstream operations, resulting in high spectrum efficiency. N uplink and downlink use the same frequency carrier, which facilitates the introduction of