### 电子工程代写|数字信号处理代写Digital Signal Processing代考|ECE310

statistics-lab™ 为您的留学生涯保驾护航 在代写数字信号处理Digital Signal Processing方面已经树立了自己的口碑, 保证靠谱, 高质且原创的统计Statistics代写服务。我们的专家在代写数字信号处理Digital Signal Processing方面经验极为丰富，各种代写数字信号处理Digital Signal Processing相关的作业也就用不着说。

• Statistical Inference 统计推断
• Statistical Computing 统计计算
• (Generalized) Linear Models 广义线性模型
• Statistical Machine Learning 统计机器学习
• Longitudinal Data Analysis 纵向数据分析
• Foundations of Data Science 数据科学基础

## 电子工程代写|数字信号处理代写Digital Signal Processing代考|Primary Transmitter Detection

Transmitter detection techniques emphasize detecting low power signals from any PU. Low power signals mix with noise from the environment and make it hard for the CR user to detect primary signals. A low signal-to-noise ratio, multipath fading effects, and time depression make primary transmissions detection very difficult for the $\mathrm{CR}$ user. We discuss some primary transmitter detection techniques including energy detection, coherent detection, and matched filter detection.

This technique does not require CR users to have knowledge of PU signal characteristics, and it is easy to implement. Because of this, it is widely used to detect primary transmissions. Let us assume $S(n)$ is the signal received by the CR user, $W(n)$ is white Gaussian noise, and $P(n)$ is the original signal from the PU.
$$\begin{gathered} H_0: S(n)=W(n) \ H_1: S(n)=W(n)+h P(n) \end{gathered}$$
Hypothesis $H_0$ indicates the absence of a PU and hypothesis $H_1$ indicates the presence of PU transmissions. $h$ denotes the channel gain between the primary and secondary transmissions. Then, the average energy $S$ of $N$ samples is
$$S=1 / N \sum_{n=1}^N S(n)^2$$
The CR user collects $N$ samples, calculates the average energy, and compares it with a threshold $\lambda$. If the average energy is greater than the threshold, $\lambda$, then the CR user concludes that primary transmissions are present. To measure the performance, we denote the probability of the false positive (CR detects the presence of PU transmissions when there is no PU transmission) as $P_f$ and probability of the detection as $P_d$
\begin{aligned} &P_f=P\left(S>\lambda \mid H_0\right) \ &P_d=P\left(S>\lambda \mid H_1\right) \end{aligned}
To improve the performance, we need to keep the PU’s transmission secured. Therefore, the false positive probability should be less than $0.1$ and the detection probability should be greater than $0.9$.

## 电子工程代写|数字信号处理代写Digital Signal Processing代考|Primary Receiver Detection

The most effective way to detect PU transmissions is to detect the primary receivers who are receiving from the primary channel. The circuit in Fig. 5 shows a simple RF receiver. It has a local oscillator that emits a very low power signal for its leakage current in the circuit. A CR user can detect the leakage signals from the RF receiver circuit and identify the presence of primary transmissions. This detection technique solves both the hidden terminal and shadowing effect problems. Since the signal power is very low, it is very challenging and costly to implement the circuit for primary receiver detection.

When primary signal features like modulation type, pulse shape, operating frequency, packet format, noise statistics, etc., are known, matched filter detection can be an optimal detection technique. If these parameters are known, the CR user only needs to calculate a small number of samples. As the signal-to-noise ratio decreases, the $\mathrm{CR}$ user needs to calculate a greater number of samples. The disadvantages of this technique are the complexities in low signal-to-noise ratio, the high cost of implementation, and the very poor performance if the features are incorrect.

In a broader sense, a signal can be called a cyclostationary process if its statistical properties vary cyclically with time. In [6], the authors presented a signal classification procedure that extracts cyclic frequency domain profiles and classifies them by comparing their log-likelihood with the signal type in the database. This technique can work very well in a low SNR. The drawback of this technique is that it needs a huge amount of computation and thus, a high-speed sensing is hard to achieve [7].

## 电子工程代写|数字信号处理代写Digital Signal Processing代考|Primary Transmitter Detection

$$H_0: S(n)=W(n) H_1: S(n)=W(n)+h P(n)$$

$$S=1 / N \sum_{n=1}^N S(n)^2$$
CR用户收藏 $N$ 采样，计算平均能量，并将其与阈值进行比较 $\lambda$. 如果平均能量大于阈值， $\lambda$ ，则 CR 用户断定存在 主要传输。为了衡量性能，我们将误报的概率表示为 (CR 在没有 $\mathrm{PU}$ 传输时检测到 $\mathrm{PU}$ 传输的存在) 为 $P_f$ 和检 测概率为 $P_d$
$$P_f=P\left(S>\lambda \mid H_0\right) \quad P_d=P\left(S>\lambda \mid H_1\right)$$

## 广义线性模型代考

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## MATLAB代写

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