Skip to main content

What are the main lobe and side lobes in Beamforming

 

 What are the main lobe and side lobes in Beamforming?

You've probably noticed that in the diagram of beamforming, there are two types of lobes in beamforming patterns. One is the main lobe, while the others are side lobes. We intend to communicate with receivers with a stronger directional path from the transmitter when we produce beams for wireless communication. We can also see side lobes in this scenario. These side lobes, on the other hand, are not necessary for effective communication. As a result, we take various procedures to remove those side lobes or to reduce the number of side lobes as much as feasible; otherwise, inter-symbol interference occurs, and signal quality suffers.

Figure: Illustration of Main Lobe and Side lobes, where the x-axis denotes the angle of arrival (AOA) and angle of departure (AOD), respectively, while, the y-axis denotes the gain/power in dB (decibel).
   

In the case of MIMO antennas, our major goal is to reduce inter-symbol interface (ISI) by minimizing the number of side lobes, therefore we deploy antenna elements at half-wavelength intervals. It's a common practice to increase the power of the main lobe while reducing the power of the side lobes.


How to plot Main Lobes and Side lobes

The plotting of the main lobe and side lobes is not difficult. To begin, measure the received power at the receiver for a specific angle of arrival or departure (AOA/AOD).

For Example

At 28 GHz, UMi - LOS, 372-meter TX-RX Separation, Transmitted Power 30 dBm


The received power changes with parameters like the angle of arrival at the receiver, as seen in the example above.



We've plotted the graph of received power against the angle of arrival of the received signal in the diagram above. These are termed side lobes.

What causes the lobes to form?

Assume we have multiple transmitting antennas. Now, we gradually shift the phases of the antennas (using phase shifters (PSs) or manually), and the signal focuses on the resulting phase angles of those antennas.

# mimo beamforming
 

Further Reading

  1.  How Windowing Affects Your Periodogram (Mainlobe Power & Sidelobe Power)
  2. Why Half-Power (−3 dB) Is Used 

People are good at skipping over material they already know!

View Related Topics to







Contact Us

Name

Email *

Message *

Popular Posts

Channel Impulse Response (CIR)

📘 Overview & Theory 📘 How CIR Affects the Signal 🧮 Online Channel Impulse Response Simulator 🧮 MATLAB Codes 📚 Further Reading What is the Channel Impulse Response (CIR)? The Channel Impulse Response (CIR) is a concept primarily used in the field of telecommunications and signal processing. It provides information about how a communication channel responds to an impulse signal. It describes the behavior of a communication channel in response to an impulse signal. In signal processing, an impulse signal has zero amplitude at all other times and amplitude ∞ at time 0 for the signal. Using a Dirac Delta function, we can approximate this. Fig: Dirac Delta Function The result of this calculation is that all frequencies are responded to equally by δ(t) . This is crucial since we never know which frequenci...
Read more

Wireless Communication Interview Questions | Page 2

Wireless Communication Interview Questions Page 1 | Page 2| Page 3| Page 4| Page 5   Digital Communication (Modulation Techniques, etc.) Importance of digital communication in competitive exams and core industries Q. What is coherence bandwidth? A. See the answer Q. What is flat fading and slow fading? A. See the answer . Q. What is a constellation diagram? Q. One application of QAM A. 802.11 (Wi-Fi) Q. Can you draw a constellation diagram of 4QPSK, BPSK, 16 QAM, etc. A.  Click here Q. Which modulation technique will you choose when the channel is extremely noisy, BPSK or 16 QAM? A. BPSK. PSK is less sensitive to noise as compared to Amplitude Modulation. We know QAM is a combination of Amplitude Modulation and PSK. Go through the chapter on  "Modulation Techniques" . Q.  Real-life application of QPSK modulation and demodulation Q. What is  OFDM?  Why do we use it? Q. What is the Cyclic prefix in OFDM?   Q. In a c...
Read more

BER vs SNR for M-ary QAM, M-ary PSK, QPSK, BPSK, ...

📘 Overview of BER and SNR 🧮 Online Simulator for BER calculation of m-ary QAM and m-ary PSK 🧮 MATLAB Code for BER calculation of M-ary QAM, M-ary PSK, QPSK, BPSK, ... 📚 Further Reading 📂 View Other Topics on M-ary QAM, M-ary PSK, QPSK ... 🧮 Online Simulator for Constellation Diagram of m-ary QAM 🧮 Online Simulator for Constellation Diagram of m-ary PSK 🧮 MATLAB Code for BER calculation of ASK, FSK, and PSK 🧮 MATLAB Code for BER calculation of Alamouti Scheme 🧮 Different approaches to calculate BER vs SNR What is Bit Error Rate (BER)? The abbreviation BER stands for Bit Error Rate, which indicates how many corrupted bits are received (after the demodulation process) compared to the total number of bits sent in a communication process. BER = (number of bits received in error) / (total number of tran...
Read more

Q-function in BER vs SNR Calculation

Q-function in BER vs. SNR Calculation In the context of Bit Error Rate (BER) and Signal-to-Noise Ratio (SNR) calculations, the Q-function plays a significant role, especially in digital communications and signal processing . What is the Q-function? The Q-function is a mathematical function that represents the tail probability of the standard normal distribution. Specifically, it is defined as: Q(x) = (1 / sqrt(2Ī€)) ∫ₓ∞ e^(-t² / 2) dt In simpler terms, the Q-function gives the probability that a standard normal random variable exceeds a value x . This is closely related to the complementary cumulative distribution function of the normal distribution. The Role of the Q-function in BER vs. SNR The Q-function is widely used in the calculation of the Bit Error Rate (BER) in communication systems, particularly in systems like Binary Phase Shift Ke...
Read more

Gaussian minimum shift keying (GMSK)

📘 Overview & Theory 🧮 Simulator for GMSK 🧮 MSK and GMSK: Understanding the Relationship 🧮 MATLAB Code for GMSK 📚 Simulation Results for GMSK 📚 Q & A and Summary 📚 Further Reading Dive into the fascinating world of GMSK modulation, where continuous phase modulation and spectral efficiency come together for robust communication systems! Core Process of GMSK Modulation Phase Accumulation (Integration of Filtered Signal) After applying Gaussian filtering to the Non-Return-to-Zero (NRZ) signal, we integrate the smoothed NRZ signal over time to produce a continuous phase signal: θ(t) = ∫ 0 t m filtered (Ī„) dĪ„ This integration is crucial for avoiding abrupt phase transitions, ensuring smooth and continuous phase changes. Phase Modulation The next step involves using the phase signal to modulate a...
Read more

Online Simulator for ASK, FSK, and PSK

Try our new Digital Signal Processing Simulator!   Start Simulator for binary ASK Modulation Message Bits (e.g. 1,0,1,0) Carrier Frequency (Hz) Sampling Frequency (Hz) Run Simulation Simulator for binary FSK Modulation Input Bits (e.g. 1,0,1,0) Freq for '1' (Hz) Freq for '0' (Hz) Sampling Rate (Hz) Visualize FSK Signal Simulator for BPSK Modulation ...
Read more

Difference between AWGN and Rayleigh Fading

📘 Introduction, AWGN, and Rayleigh Fading 🧮 Simulator for the effect of AWGN and Rayleigh Fading on a BPSK Signal 🧮 MATLAB Codes 📚 Further Reading Wireless Signal Processing Gaussian and Rayleigh Distribution Difference between AWGN and Rayleigh Fading 1. Introduction Rayleigh fading coefficients and AWGN, or Additive White Gaussian Noise (AWGN) in Wireless Channels , are two distinct factors that affect a wireless communication channel. In mathematics, we can express it in that way. Fig: Rayleigh Fading due to multi-paths Let's explore wireless communication under two common noise scenarios: AWGN (Additive White Gaussian Noise) and Rayleigh fading. y = h*x + n ... (i) Symbol '*' represents convolution. The transmitted signal x is multiplied by the channel coeffic...
Read more

Comparisons among ASK, PSK, and FSK | And the definitions of each

📘 Comparisons among ASK, FSK, and PSK 🧮 Online Simulator for calculating Bandwidth of ASK, FSK, and PSK 🧮 MATLAB Code for BER vs. SNR Analysis of ASK, FSK, and PSK 📚 Further Reading 📂 View Other Topics on Comparisons among ASK, PSK, and FSK ... 🧮 Comparisons of Noise Sensitivity, Bandwidth, Complexity, etc. 🧮 MATLAB Code for Constellation Diagrams of ASK, FSK, and PSK 🧮 Online Simulator for ASK, FSK, and PSK Generation 🧮 Online Simulator for ASK, FSK, and PSK Constellation 🧮 Some Questions and Answers Modulation ASK, FSK & PSK Constellation MATLAB Simulink MATLAB Code Comparisons among ASK, PSK, and FSK    Comparisons among ASK, PSK, and FSK Comparison among ASK, FSK, and PSK Parameters ASK FSK PSK Variable Characteristics Amplitude Frequency ...
Read more