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Questions related to Communication Engineering
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Any body who wants to guide me???
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Moreover, you can consider IRS (INTELLIGENT REFLECTING SURFACES) and NOMA in LTE networks.
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In literature, there is no closed form for the information rate of visible light channel. Consider the visible light channel as
Y=ho*xo+ sum( hi *xi)+N,
Y: received signal, h the VLC channel , xi  (xi >0) is the transmit signal with average transmit optical power constraint E{xi}=p, N is the Gaussian noise.
In some paper they evaluate the information rate of this channel using Shannon capacity formula R=log(1+SINR), where SINR= (r*h0*p)^2/(N+ sum (r*hi*p)^2). Is this still a valid and measure with the mean and positive signal constraints??. 
Some papers discuss DC biasing for input signals then at receiver they removed the DC bias and find a relations with DC bias and optical transmit power. will the DC biasing make the the Shannon capacity formula valid for such channel?  
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Have a look at following article,
Interference Mitigation for Visible Light Communications in ... - MDPI
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While designing any general optical CDMA network these two terms are often used interchangeably. I want to know the analytical relation between these two. Kindly help
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Q=sqrt(2) erfc^-1 (2 BER)
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I am working in free space optics i need code source matlab please if anyone have help me...best regard 
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Hello everyone
can someone send me codes for FSO/RF system for matlab ?
thank you
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when i use interpolation sweep, the option of sweep is hidden from this box. why?
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Also, I would appreciate it if you could give me some relevant references.
Thanks :)
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Please let me know if any book or website is available for reference 
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Can someone please provide me MATLAB code for calculating PAPR of OQAM/FBMC system
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Is there someone who has a research paper?
Preferably for frequencies around 700 Mhz, 868 Mhz, 900 Mhz.
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this pdf>>>>>>
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Hi, How can we calculate the entropy of  chaotic signals? Is there a simple method or formula for doing this?
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Since i am not able to get proper VSWR as well as Return Loss.. at Freq 1.5 ghz.. you can take any number of turns and any radius of helix. please.. I have attached the paper if it can be implemented in CST.. I need it please..
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You may have the axis too close to your shape or inside your shape, or the pitch is too small so that the helix doesn't miss itself when it goes round in a circle. Start with a small shape a long way from the axis, with the pitch much bigger than the height of the shape and see what it looks like, then make the shape larger or move the axis closer, or reduce the pitch, until you have the shape you want.
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what is the difference between nakagami-m and general fading, where they are applicable?
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The Rayleigh distribution is frequently used to model multipath fading with no direct line-of-sight (LOS) path.
The Rician distribution is often used to model propagation paths consisting of one strong direct LOS component and many random weaker components.
The Nakagami- m distribution is its good ft to empirical fading data. It is versatile and through its parameter m, we can model signal fading conditions that range from severe to moderate, to light fading, or no fading.
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BER analyzer parameters meaning.
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The reliability of data transmission characterizes the probability of getting a distortion for the transmitted data bit. This indicator is often referred to as the Bit Error Rate (BER). The BER value for communication channels without additional means of error protection is 10-4 — 10-6, in optical fiber — 10-9. A ber value of 10-4 indicates that on average, one bit is distorted out of 10,000 bits. The q-factor of the receiving system Q is determined from the expression:
Q = GA/TC,
or, in logarithmic form:
Q[dB] = GA[dB] - 10lgTC[x].
It is the q-factor of the receiving system that determines the signal-to-noise ratio (C/N) at the output of the low-noise Converter (LNC or LNB). It is important to note that the final C/N value does not depend on the LNC gain.
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How should I determine threshold on received signal power(underwater acoustic signals) so that the signal can be decoded correctly. I understand that the threshold may vary device to device but I want the value for research purpose independent of any device.
Regards
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I am not able to visualize your experimentation.Is the plot between I and Q components or between the vector components of the particle velocity channel?
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Kindly, suggest me some SCI/SCOPUS indexed journals paid/unpaid in RF and Microwave Engineering with 1-2 months of review time.
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The Journal of Microwaves, Optoelectronics and Electromagnetic Applications (JMOe), published by the Brazilian Microwave and Optoelectronics Society (SBMO) and Brazilian Society of Electromagnetism (SBMag), is a professional, refereed publication devoted to disseminating technical information in the areas of Microwaves, Optoelectronics, Photonics, and Electromagnetic Applications. The review was done within 12 weeks. Authors are not charged for the article Processing and article Submission costs. 
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I am recently studying "Spatially sparse precoding in millimeter wave mimo systems" at
So, the attached matlab codes is for the simulation of figure 3 in the paper.
It seems like that I have success in SVD(optimal) and spatially sparse precoding but not at "Beem Steering method".
This method seems based on the paper "The capacity optimality of beam steering in large millimeter wave MIMO systems"
I appreciate your comment about what's wrong in my implemenation.
PS.
laprnd.m is not my implementation. It is on the mathworks site
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Dear Hoil Kim
In your code, you have taken angle spread as 7.5 degree. In many papers, they have taken same value. Can you please justify this value.
Further, if we take case of mmWave channel with single ray per cluster, ie. Nray=1 (I have seen some papers), what will be the value of angle spread? What changes needs to be done in your code, if Nray=1.
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Hi I am confused about the concept of signal quality index. what is signal quality index? what is the relation between signal quality index and signal strength? can we determine signal strength from signal quality index?
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As Martín Martínez Villar stated, I don't think there is a unique definition of a signal quality index. However, if you consider for example the field of (biomedical) signal processing, by a signal quality index you usually mean a value between 0 and 1 (or 0 and 100%) that indicated how "good" (free from noise and other artifacts) the signal of interest is.
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I am a Master student in Communication and I am looking forward to plan my futur career.
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Doesn't it vary from individual to individual?
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In 0.1 - 10 THz regime, how to reduce the path loss?, what are issues associated with path loss?
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As said by Zahed Hossain you should not select THz frequencies for wireless communication that have high water vapor absorption. In addition to wise selection of THz frequencies and high gain antennas you can overcome high pathloss penality by beamforming with ultra-massive MIMO antennas.
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I just came across a problem in power amplifier used in communication chain which exhibits nonlinearity due to memory effects.This can be nullified with a help of digital pre-distortion using signal processing algorithms.
Can anyone please tell how it is achieved and explain the math part behind the algorithm?
Suggestion of book or a research article is preferred.
Thanks
Rakesh
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A good place to start would be understanding the behavioral model first by any scholar book such as :
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I am working on transmitting ECG signal over wireless body area networks. According to IEEE802.15.4 standards , I am using ZigBee transceiver at 2.4 GHZ . Complex baseband equivalent channel model is used.
The steps are as follows :
1.      Signal Compression
2.      Quantization
3.      Coding
4.      OQPSK modulation using the matlab function (oqpskmod)
5.      Fading Channel plus AWGN
6.      Equalization
7.      OQPSK Demodulation using the matlab function (oqpskdemod)
8.      Decoding and Dequantization
*  According to the IEEE 802.15.4 standard, a pulse shaping step is performed in the transmitter after the OQPSK modulation step . 
I didn`t perform this pulse shaping process, and I obtained reasonable results. Is it necessary to perform this step ? 
If  yes , How should the receiver be modified ?
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Your Design should follow IEEE 802.15.4 standard. Since pulse shaping is being used in the standard and ZigBee utilizes the IEEE 802.15.4, you can not ignore it.
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I am analyzing the complexity of resource allocation problems in NOMA systems. The network model is shortly summarized as: a base station (BS) and multiple users (UES), singles for all UEs are superimposed at the BS, and the objective is to allocate at the BS so that optimize the resources. In addition, I am using the network sum-rate maximization is a baseline, which is NP-Hard according to my own finding. However, I am not sure about this (NP-Hardness of the sum-rate maximization problem).
Does anyone have any suggestions for me?
Many thanks in advance.
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Most of works are relating to downlink NOMA. For uplink NOMA, different system model and problem formulation should be considered.
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What is CQI standards for D2D commmunication, can any one describe for me CQI in D2D?
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A comprehensive survey on D2D communications, covering different aspects related to modeling, mobility management, and applications can be found here:
Article A Survey of Device-to-Device Communications: Research Issues...
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I can´t get data from simulator because of some license issue/error.
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ftp://cddis.nasa.gov/gnss/data/daily/ on your browser and select desired IGS Station.
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I am working on the implementation of a small Wireless Sensor Network using USRP devices to form a star network consisting of multiple sensors and one controller. I am looking for a simple mechanism to synchronize the nodes with the network controller. There will be no communication between sensor nodes.  
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Dear Tasnim Nazal,
Please take a look at this attached file.
Best regards
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Antenna design in one software varies with result in another software. Also which one is better for mesh analysis.
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For antenna parameters HFSS is quite good choice.In case of it's physical and equivalent circuit simulation please try another software, ADS
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The main functional block of a microprocessors is the ALU (Arithmetic and Logic Unit) because of its involvement in all computing activities. The important tasks of ALU are arithmetic and logical operations. Speed of the microprocessor mainly depends on ALU’s performance. Most of the processors are included with stand alone design for arithmetic operations. In very large-scale integrated circuits (VLSI), ALUs with various bit-widths are required to perform operations efficiently.
Papers:
S.M. Swamynathan, V. Banumathi “Design and Analysis of FPGA Based 32 Bit ALU Using Reversible Gates,” International Conference on Electrical, Instrumentation and Communication Engineering (ICEICE2017), 2017.
Mohammed F. Tolba, Ahmed H. Madian and Ahmed G. Radwan “FPGA realization of ALU for mobile GPU,” 3rd International Conference on Advances in Computational Tools for Engineering Applications (ACTEA), 978-1-4673-8523-7/16/31.00, IEEE, 2016.
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It depends upon the application for which the digital system is designed.
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we come to generation that subcarriers are no longer orthogonal to each other. here the different parameters such as amplitude, frequency and phase will change for each subcarrier. by using cognitive radio the spread spectrum is reduced. GFDM plays a major role here. im looking for an MATLAB code or LABVIEW code to analyze this. 
anyone related to this work, kindly reply 
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you can search the Matlab Community (File Exchange) or request from 5gnow project
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What is the main difference between dual band and dual radio?
Let
A system equipped with:
Dual Band= 2.4 GHz and 5 GHz
Dual Radio=802.11 and 802.14.5
where 802.11 with 5GHz is deploy between air to air link
and 802.11 with 2.4 GHz between air to ground.
similarly some nodes are also connected through 802.15.4 with 2.4 GHz between air to air.
The above system is dual band dual radio
or triple band dual radio
or triple band triple radio?
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Dual band refers to a device which uses two different frequencies to communicate.
Dual radio refers to a device which uses two different protocols to communicate.
Maybe an illustration would help. A dual band device is like a person at a party who can move between two different rooms (different frequencies) to talk with other people, while a single band device would be limited to talking to people in only one room. On the other hand, a dual radio device can speak with people who speak in two different languages, while a single radio device can only speak one language.
A dual radio device is typically used as an intermediary between two different networks like 802.11 (like WiFi) and 802.15.4 (like many wireless sensors).
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What is the practical operating frequency of FEMTOCELL. What kind of antenna (arrays) is used in the recent models and what is the range?
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I have designed an microstrip multiband antenna...got the frequencies has 12GHz,13GHz 28 GHz and 38GHz... actually mmwave frequencies...can I use it for femtocells is my question??
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One of the threat to humanity is THE emergence intelligent machines. When AI gets full control and when sky-net comes to exist....might be already there, ....the plan is to enslave humanity rather than making things easy for him. I know, soon the robots replace many employees and do many complicated jobs including industry works, medical works (complicated surgery, scanning etc), cooking, nuclear and other energy sector operations, care works for child and elderly etc.
Machines are smart and fast; they don't get tired, they don't do random (ie they are error free). They are very adaptive, capable of evolving abruptly and are self aware. Machines spy on humans 24/7, on every little corner of the earth due to the emergence of 5G which gives them this ability, the ability to track and identify everyone for every space-time on the glob with their direct satellite connection...and this means the end of human privacy. I have no idea what the fate of human being will be in such times.
Making human half machine half human (cyborg), a bio-mechanical being is one application of this field to create superhuman soldiers. Many countries including Russia, US, china, UK are using such technology side by side with their genetic engineering research to strengthen their military. They are always up to humanity, to destroy the human race from the face of the earth in every way possible.
5G is a key together with AI for all these to succeed. 5G towers are already in place to begin work in US and UK (some are already in operation). 5G has a data speed of 100 times that of the 4G network system and the towers should be installed very near to the client residents as it work in very short distance point to point communication. It uses very short wavelength or very high frequency which obviously expected to cause caner and other serious side effects on any living cell due to its high frequency microwave radiation. I know many people are not aware of the downside of such technology and the potential damage it might cause. It is my belief that 5G radiation is responsibly the cause for the massive death of birds and other animals near to such towers in US. The towers look like this, you might find one of these on your building or neighborhood.
I would like to know what you think about 5G network and the technology related with it.
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I rally liked your description of the expected disastrous effects of 5G, and I asked Dr. Ted Rappaport (one of pioneering professors from the NYU in the field of mmWave and 5G) about the health effects resulted from using such frequencies and he mentioned that he did this research on that topic before beginning his experiments on the mmWave channel measurements few years ago:
It is obvious that using these frequencies (i.e. mmWaves) is far from ionization that causes health issues for humans if they are used in the right way and according to federal regulations.
Best Regards.
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It is needed in wide band reflectarray. Please clear this multiple of 360 degree effect on the bandwidth.
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I recommend you to read this paper:
Best regards
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To get ouput graphs I need to generate vector and scalar graphs but can't find any way to do it. Only an event log file is generated.
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how can i generate PDR vs distance graph in mixim omnet++ i have scalar and vector files also Atta ur Rehman Khan Pankhuri Singh
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User1- power(p1)
User2- power(p2)
P1>p2, how to detect P1 in case of power division multiplexing in NOMA in terms of matlab at the receiver
Thanks
Brij Mohan Kumar
M-tech (Communication Engineering)
IIT Patna
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Brij,
The algorithm used to separate the two signals S1 and S2 of the two subscribers in NOMA is the commonly the successive interference cancellation where one detects and decodes the strongest received signal and subtracts it from the total received signal, then the remaining received signal will be that of the weaker subscriber signal which can decoded.
Assume that the received signal can be modeled by the equation:
r= sqrt P1 h1 S1+ sqrt P2 h2S2 + sigman = r1+r2+ sigman the parameters have their usual meaning
In order to separate the signal in NOMA if P1=P2 as the of users can be considered equal, then h1 must be much greater than h2 which means that subscriber one is much nearer to the base station.
Therefore r1>>r2, and r2 can be considered as noise and S1 can be detected and decoded. And consequently r1 can be calculated and cancelled. So, it is clear that h1 and h2 must be known for signal separation in NOMA.
For more information please follow the link:
Best wishes
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In optiwave the eye diagram shows the q factor how is this calculated?
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The eye diagram represents the waveform of the logic one and the logic zero drawn on the screen of the oscilloscope with the symbol time made to make out the to total horizontal length of the screen. If The signal is ideal one and zero appearing a rectangular pulses, then the eye will appear fully open. As the pulses are distorted in phase and amplitude the eye will be no more full open it begins to close. However the most important issue is the eye lines passing under the decision threshold. If this happens the bit will be in error.
So one counts the total number of bits N, and the part of then that lies in the decision threshold which is Ne, the number of bits in errors.
Then the bit error rate ber will be = Ne/N,
Since ber= .5 erfc Q/sqr2
From the above equation one can calculate Q for a given ber.
Best wishes
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Current research focus on 5G is on which bands in the frequency spectrum.
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1) 3.5/3.7GHz : Band n77/n78
2) 4.5GHz : Band n79
3) Upto 6GHz : BW>500MHz (WRC15 band)
4) 10GHz, 17-18GHz, 24-25GHz, 27-30GHz, 32GHz, 36GHz etc (WRC19 band)
5) 26/28GHz : Band n257/258
6) 38GHz, 40.5-43.5GHz, 60GHz etc freq. bands
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In optimization problem often we use local optimum but is it global? Or are there any meta-heuristics algorithm to obtain global solution? If there any then what is the name of that algorithm and if possible how we can get that solution?
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I wish not to let you down, but the basic answer is "very seldom", and another one is "you will not know if you have stumbled upon an optimal solution, because there is no natural termination criterion based on the concept of optimality". (In contrast, a branch-and-bound, or branch-and-cut, methodology is based on local AND global bounds on the optimal value generated throughout the procedure, and in most cases the correct procedures will either fix some variables to their optimal values before termination, and they will be able to discard a very large portion of the search space based on parts of the search space being infeasibie or inferior, in which case we do know for sure that an optimum has been reached.)
If you have a structure of the problem that makes it emanable to be solved by special methods, such as Benders decomposition - when you have a mix of integer variables and continuous variables. you also have a fail-proof method.
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I try to implement FBMC in simulink. I have already matlab code for FBMC but when I implement in simulink, it creates problem as poly phase network block is not available in simulink library.
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No, I have implemented FBMC using code in m file but I am struggling to design it in simulink specially in using polyphase filtering.
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I want to design an Op-Amp using CMOS technology. For that I have been designing a differential amplifier as an input stage. I am stuck at transistor sizing. Recently I came across gm/id methodology for transistor sizing. I would like to know how this method can be used to decide the aspect ratio of transistor. Please share some material, if possible.
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1) Zigbee.
2) Wi-Fi
3) Bluetooth
4)NRF24L
etc
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Thanks Raees Asif.
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What kind of projects are out there in neural system analysis?
What are the take aways?
I know it can be applied to many of the industries, commercials, and at home.
But I am bit vague or cannot grip on what the term stands for and what can be done within.
I honestly thought neural systems are somewhat related to bioengineerings.
Would you kindly give some explanations??
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Having hands on to data makes it easier to understand, Pick a language(matlab or python) and select an algorithm to see how it works on the data, look for youtube videos with simple examples..
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Which simulator is better to simulate D2D communication in LTE networks ?
Thanks.
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Trust me,
You can not rely on the answers here.
Every one is talking about his/her favorite simulator based on his experience and background.
You can see always a conflicting answers in this regard.
You need to quickly test both first.
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I want to implement power saving mechanism in ieee 802.11ac networks. I want guidelines how should i design in netsim software?? please help me through this.
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You could also try using the latest Transmit Power control algorithms and interface them with NetSim
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For my PhD topic and research, I wish to work on intercell interference mitigation (ICI) in heterogeneous networks (HetNets) using cell range expansion (CRE) in combination with hybrid power control (HPC) techniques. How can I effectively implement this?
Actually, I intend exploiting the advantage of CRE in offloading some users from macrocell to small cells (picocells or femtocells). Thereafter, power control technique/algorithm would be used to mitigate co- and cross-tier interference to offloaded users. I will appreciate any guideline on how to implement this, coupled with any helpful codes, links, textbooks and softwares.
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Can you please share, any Matlab code for Interference mitigation you find useful?
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Hi
My question is related to underwater acoustic sensor networks.
I have written the attached matlab code to calculate required transmission power based on distance between the sender and receiver and SNR threshold at the receiver(My aim is to calculate energy consumption ultimately). However I get infinity for required Intensity(Req_I) and Required Transmission Power (Req_Pt). Please suggest what is the mistake that is resulting in my required transmission power to be infinity and how can I fix the problem.
Best Regards
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In your code,mention the units associated with each parameter.you have calculated TL in nepers but added like TL in Db and converted again to nepers which I feel the reason for infinite source level
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I am designing a VLC system with DMT. For the channel response, I have chosen BPSK on all subcarriers and calculated the SNR of each subcarrier from BER-SNR relation.
For subcarriers with SNR greater than required SNR for BER of 10^-3, I have increased the number of bits over that subcarrier. (for example if subcarriers  SNR is greater than 9.8, I have changed the bits assigned from 1 to 2).For this new bit-loading, I have found that SNR of both QPSK and BPSK loaded subcarriers getting degraded. How can I arrive at a decent bit-loading to maximize the transmission?
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Thank you yousif , lateef and aparna. I have found these references very helpful.
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I am interested in understanding what problems are remaining for reducing or removing wind noise for outdoor noise detection source localisation or speech enhacement.
FYI have a resonable understanding of non-stationary noise characterisation and beamforming approaches.
Thankyou in advance
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Hi Viara,
Thank you for your reply.
Your right I did ask several questions.
Let me try and re clarify a single questions I have for someone with experience in outdoor acoustics testing. How influential is the effect of atmospheric turbulence present on compact microphone used for acoustic mapping an outdoor source ie Wind turbine in the low frequency range. Besides limited spatial aperture of a array is correlated turbulence a primary limiting factor in the beam former separating two closely spaced acoustic sources.
Thank you.
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What could be the maximum distance that one can control a UAV from?
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I'd use commercial 3G-4G mobile phone networks in order to send and receive short communication lines that help upload discrete commands (eg. Speed, Altitude, Go to a preset waypoint, Cancel mission, Go back home....) and download basic status information. Wouldn't work for downloading real time imaging, but maybe acquiring some basic environmental information.
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Dear and Respected Colleagues
I am requesting to all those respected mentors and researchers working on Optical Communications Please help me on PM to IM conversion to generate UWB pulses?????
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Dear B Das
I have a question on SOA. Please help
It has been learnt that if AWGN/White light source is coupled with CW probe and Pump signals (Data signal) and then the cumulative signal is launched in a SOA for XPM and amplification,then the SOA is very less noise tolerant and the pulse shapes and Eye diagram badly degrades at the receiver side.Why SOA is very sensitive to noise and less immune to it?
please comment and share any written literature on this property of the SOA
regards
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Having a periodic pulse signal p(t) with
p(t) = 1 for (n-1)*P < t-phi <= (n-1)*P+d*P and
p(t) = 0 for (n-1)*P+d*P < t-phi <= n*P
where phi is the phase shift, P is the period and d is the duty cycle.
(phi in [0,P), d in [0,1])
Assume that we sample the pulse signal K times every ts, i.e., we have p(k*ts) for k=0...K-1.
Is there a limit on the accuracy of estimating the pulse parameters phi, P, d solely due to sampling?
To my understanding, since (depending on d) there exist even and odd harmonics up to infinity, one is not able to sample with the double of the highest frequency. Thus due to image frequencies errors are induced. But how can this be characterized?
Thanks in advance!
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Dear Andrea,
It is a while, but the question we were discussing has lead to the following contributions, maybe of interest for you as well:
Hans-Peter Bernhard, Bernhard Etzlinger, and Andreas Springer, "Error Characterization of Duty Cycle Estimation for Sampled Non-Band-Limited Pulse Signals With Finite Observation Period," Europ. Sig. Process. Conf. (EUSIPCO), 2016
and
 
Hans Peter Bernhard, Andreas Springer, "Linear Complex Iterative Frequency Estimation of Sparse Pulse and Point Processes" : 2017 25th European Signal Processing Conference (EUSIPCO 2017)
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I am working on systematic polar codes. But the problem is, after decoding we need to encode the decoded bits again to have the original information. 
However, belief propagation (BP) decoding provides soft output. There is a problem again: after one iteration, the output (which would be used as the input of next iteration) is changed. Therefore, if it is used as the input in the second iteration, it generates an error. In this case, what would be the possible solution?
Thanks in advance. 
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Dear Mohamed-Mourad Lafifi,
Thanks for your help. Although I have found the solutions, these articles will help someway. 
Thanks again. 
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i want to buid a scrambler in matlab for 802.11 standard
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Dear Kishan,
Most real-world data contains repetitive components. Examples include sequences of constant values such as a video image that doesn’t change from one frame to the next, a document with sections that are all one level (e.g. white), or repetitive data values in a file or database.
Two possible problems are introduced by this non-random data:
1) long sequences of certain values (zeroes, ones) will result in a signal that may not have enough transitions to allow for clock recovery (for data recovery and synchronization). You can read basics of "clock recovery" even from wikipedia.
2) Morevoer, when these (long sequences of zeroes or ones) values are transmitted, the periodic components of the signal result in peaks in the spectrum that have larger than average power. These strong discrete frequency components can cause interference.
To solve these problems most communication systems use “scramblers” to remove undesirable patterns in the data.
I hope the answer can help you.
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Hi everyone,
Could anyone show me some approaches for detecting and extracting wideband radar signals in ELINT systems? The receiver bandwidth is about 500 MHz.
I am currently following the time-frequency (T-F) analysis approach. However, I don't know which T-F technique is the most efficient one for this application?
So, could anyone help me in narrowing down the research?
Many thanks.
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Hello George Slade,
1. Thank you for your caution about the pre-processing power. My mission is to design an algorithm which is able to detect and extract all radar pulses in the instantaneous bandwidth of 500 MHz in real-time.
2. I have no idea what I am looking for because there are so many types of radar signals out there. There algorithm should be universal enough to detect and extract most of radar signals at as low SNR as possible.
3. I have read some time-frequency analysis techniques. In the future, I will try with Short-time Fourier Transform and Wavelet transform techniques. Some other T-F techniques (e.g. Wigner-Ville distribution, Choi-Williams distribution, ...) may not be suitable in this scenario because of the cross-terms.
Do you have any additional suggestion for me?
Thanks and Best Regards,
Van Long
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I would like to play an audio file Meanwhile plotting and updating a diagram. However, my audio file is interrupted. I would like to play audio file smoothly in background and update the figure at the same time.
for i=1:10
player = audioplayer(audio, Fs);
play(player);
scatter(x(i),y(i),'r.')
end
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ETSI bursty traffic model
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---XXxx----YYYyyyy----
---^............^     Interarrival time
----------^...^     Intersession idle time
NOT THE SAME. 
I link to a good paper worth reading. 
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Can any one suggest application of microwave absorbers in 5G communication systems?
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Main application of absorbers is isolation enhancement. They also can be used as filters and attenuators. 
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If yes, how do you treat the weights for the two different variables? Do you launch different weight vector for position and another one for the velocity?
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Thanks Enrique. Well, your assumptions are true but weights are connected to and calculated based on the measurements vector. Let's say that we have the state vector you proposed above with a measurement vector has ranges and rate of change of ranges as measurements which are associated with the position and speeds in the sates vector. Now, we you calculate the weights using a measure of the distance between the measured quantities and the predicted ones. Here you find that you are getting numbers in very deferent ranges (order of magnitude) since the measured quantities are in different domains i.e. range and rate of change of range. When you normalize these calculated weights, the smaller ones will vanished and have no effect the process. So, the question again, or what I found is that I need to calculate the weights separately, normalize them, and then merge them together but wanted someone to confirm this if they noticed same thing.  
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I am trying to simulate a Cognitive Radio Sensor Network using Matlab. Can anyone be of help with a code for doing this? NS-2 can also be ok.
Thank a lot and be blessed
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CRN configuring in NS-2  has more difficuties. Simulink can be tried out...
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Dear all
I am writing a paper in the field of LDPC codes. I have a problem for simulating my proposed parity check matrix and obtaining the chart of bit error vs SNR values. I need to an expertise co-author in this field for finishing my paper. can everyone help me as co-author for simulating my paper? please contact me and I will explain more details
.
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Dear Dr.Kaining Ham
Thank you for your comment.
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When the number of receive antennas is larger than transmit antennas, we have   the relay beamforming matrix is written as wt*wr^{H}, where w_r \in C(M+n), and w_t \in C(M)? Is it reasonable for practical communication systems?
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Think of common broadcast stations.  An indefinite number of receiving antennas can be used with only one transmitting antenna.  
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Any suggestion/hint will be appreciated.
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Hellow, Of course FHSS is one, but is fundamental that in addition to secure on physical layer, the algoritms of channel codding, modulation ant others will be properly settings, but that leads to secure system of truth 
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Dear friends
plz let me know the mathematical relation of bandwidth of optical bandpass filter(OBPF) with FWHM/Pulse width of optical gaussian regenerated pulse at OBPF output???
i will be very obliged for your help
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 Dear Mohammad.
The paper you attached in last massage states that they tuned pulse  train of 5 GHz or 10 GHz frequency. Now understand the thing. This developed system can used for any Gbps data rate input.
How look:
For example: 
The input signal is QPSK encoded to one of 4 phase positions for each "wave/cycle of any ps in the case of attcahed paper". If 2 bits can be carried per symbol. Thus:
Thus a 10 GHz carrier can carry 20 Gbps of data in ideal case. or 5 GHZ carrier can carry 10 Gbps of data in ideal. So data rate depends upon on the input signal modulated as well.
Also try to understand the concept of sentence mentioned in paper on page 1, second column line No.13 "The narrowest pulsewidth obtained for 10-Gb/s signal is around 20 ps."
Hope it may help somehow.
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I am working on WSN localization for the Indoor Environment. I want to know either the use of yagi antenna is suitable for localization. What my thoughts are: When transmitting, a Yagi antenna allows more transmitted power to be sent in the direction of the receiver, increasing the received signal strength. When receiving, a Yagi antenna captures more of the signal, increases signal strengths. This can also reduce interference that makes this antenna ideal for indoor localization. Plz do help me regarding this as I am new in antenna design and configuration. 
Secondaly, do calculation of compass sensor from antenna angle helpful in this framework. 
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Hi,
Yagi antenna is with a lot of secondary lobes introducing mistakes  to determine easely the direction of the maximum signal, better is to use a Horn antenna, also frequency and  wider of the band is an important criteria to choose the right horn model
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Why so many of wireless gadgets operate at 2.4 GHz or 5.8 GHz? What is the reasons for choosing this specific frequencies for ISM bands?
Your answers will be highly appreciated.Thanks
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The frequency allocation is organized in world wide basis by international communication union. Every country has its own authority for regulating the use of the frequency spectrum. The bands are allocated fro specific wireless services. The ISM bands are allocated for industrial, scientific, and medical wireless services. The 2.4 band is allocated for microwave heating. 
In general there are factors governing the frequency allocation process where the frequency spectrum bands are divided among specific services some of them are licensed and the other is unlicensed.
For the factors governing the frequency allocation process please refer to the paper in the site:  https://www.itu.int/dms_pubrec/itu-r/.../R-REC-SM.1131-0-199510-I!!MSW-E.docx
best wishes
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Now a days ,For multiple frequency for different application,we must require frequency reconfigurable antenna.But it is challenging to design .
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Dear Deepak,
Can you be more precise about your question?
If you want to know just the challenges in designing the frequency reconfigurable antennas, you may refer to this paper: DOI: 10.1109/VTCFall.2012.6399212
Good luck
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Hi 
I need to implement my own channel mapping based on a different scenario.  For example, in the list of bad channels and good channels which use RSSI or PER, I want to increase the BER for good channels in a certain time period. Another example can be rescheduling the channel list based on different timing or clustering. 
I was wondering if somebody can help with the reference or hardware and BLE stack suggestion.
Regards
Ali 
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Greetings Ali
The AFH function in Bluetooth systems is critically specified in the Bluetooth Standard (Core Specification Document). Commercial chipsets are certified for compliance to the standard, and will not generally allow for deviations to specified methods and techniques.
However, if you do obtain editable source code, you can go "off-standard" and play with the internal AFH parameters in the lab. Note that your device may not work with other commercial devices which are looking for explicit adherence to the standard.
For details on the AFH algorithm and methods, download and review the Bluetooth Core Specification, which is currently in a version 5 release.
Regards
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Compressive Sensing is very popular technique to process sparse signal. most of the researchers applying CS technique for DVB-T/DAB or OFDM, GSM based passive radars whose bandwidth is small, whereas FM has huge bandwidth.
if CS is not suitable suggest me any other techniques.
Thank you  
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@Venu Dunde,
I have been working  on radar technique to improve range resolution, side lobe mitigation and target detection and  recently I have published a novel solutions with different technique (especially the antenna design part), Significant directivity and Side lobe reduction!
I wish this can help you:
A Novel Elliptical-Cylindrical Antenna Array for Radar Applications
Abstract:
With the advancement of radar technology, detecting objects, determining the structure of the target, and estimating the direction and the speed is prominently increasing. There is no doubt that small cross section targets are hardly identified and determined. This problem demands the need for ...
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I use following code to simulate a QPSK signal through 3-path Rayleigh channel,
signal_r=2*(rand([Ls,1])>0.5)-1;
signal_i=2*(rand([Ls,1])>0.5)-1;
QPSK=signal_r+1i*signal_i;
Es=((QPSK)' *(QPSK) ) / Ls;
N0=Es/10^(SNR_dB/10);
h=sqrt(P/2)*(randn(1,3)+1i*randn(1,3));
fading=conv(QPSK , h);
noise=sqrt(N0/4)*( randn(length(fading),1)+1i*randn(length(fading),1) );
received = fading+noise;
Is it right?
Why do I need to multiply (randn(1,3)+1i*randn(1,3)) by sqrt(P/2)? The denominator is always 2?  How do I define P ?
h is called  impulse response of Rayleigh channel? 3 paths are also called 3 taps?
Thank you for your answer.
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Hello,
overall, your code is not bad, it just needs to be improved. I mean: 
- you didn't create a signal, but symbols. In order to simulate a single carrier signal, you just have to oversample (zero pading) and filter (root raised cosine for instance) the symbols.
- I don't understand why you multiply your channel by sqrt(P/2). If it is for a normalization matter, then it is wrong. You may remove it. However, your 3 taps channel is OK, the Rayleigh-ness of the channel is intrinsic to the function randn. In further  works, just take into account the delays and the gains of the taps. But for a first test your code is fine.  
- Then you can use the conv function to filter the signal by the channel.
- The SNR is usually defined as the power of the received signal over the noise variance. So for a given SNR : assess the power of the received signal P = sum(abs(x).^2)/length(x), then create a noise vector of power 1 : N1 = sqrt(0.5)*(randn(1,L)+1i*randn(1,L)), and finally create the noise vector with expected power: 
N = sqrt(P_N)*N1 with P_N = P*10^(-SNR/10)
- Finally, the signal is the sum of the transmitted signal over the channel plus noise N.
Regards
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Can any one offer a qualitative solution as to why partial grounding helps in enhancing bandwidths in patch antenna?
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Partial ground planes and ground planes with specially designed slots play a key role in obtaining UWB behavior. Basically, partial grounds reduce the energy stored in the substrates. The reduction of energy storage in the substrates causes to decrease in Quality factor. As Q factor decreases, bandwidth increases. Partial ground plane means back radiation. Therefore, more radiation loss. hence, Q factor decreases and as a result of that, bandwidth increases.
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I want to know  how can the coherence times of a 3.5 GHz channel can be scaled to a 800 Mhz channel?
Can someone give me an idea?.
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many thanks
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Hi, i would like to estimate my channel (Multipath Rayleigh channel) using preambule. I don't understand how to do this in Matlab and how to know the length of the frame( the period to insert the next preambule) and what will be the suitable function to model the channel in this case (in terme of matlab code)
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No but i work using Matlab Software
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trying to decide if demodulation is done in DSP itself ,instead of demodulation circuit
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Digital signal processing can be used many functional building blocks of the advanced communication systems. The soft ware defined radio technology is now a common practice for implementing advanced wireless transceivers standards in mobile communication networks, wi phi and wimax. The digital processing can be implemented either using field programmable arrays FPGAs of digital signal processors DSPs devices or a plat forms composed of the two chips in addition to general purpose processors. 
As for the functions that can be implemented are the source coding, channel codeine, encryption, multiplexing. filtering, modulation, mixing for frequency up conversion and the inverse processes. Normally the modulation is carried out at the base band model.
It can also realized in the pass band but one has to choose the carrier frequency as low as possible to save in the required computations as as the sampling frequency increases the computations required increases.
Logically the inverse processes in the receiver are also implemented using the same platforms.
So, the mixing can be realized using DSPs but you have to compromise the carrier frequency used  to save computations and power of the DSP.
It is advisable to carry out the mixing processes in the analog front end of the transceiver and use zero IF or low if mixing to lower the sampling frequency and save processing effort and power consumption. 
The system design helps choosing the most suitable system architecture of the wireless transceivers.
Best wishes 
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Hi everyone, I'm working on arithmetic compression. I am trying to compress the channel iut of the international standard. With my algorithm I have a compression ratio of 0.86 if I take the channel A iut with a modulation ofdm of 128 subcarriers.
NB: I send the exponential form of the complex numbers therefore of the angles comprised between 0 and 2pi.
Then my question is: would anyone have an idea to create an algorithm arithmetic enough powerful because mine gives results that do not bother me
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Thank you dear Luay Shihab . I think this is very clear resume on the compression. Now I understand better the compression process.
So on  practice or  implementation. My idea is to implement arithmetic compression which is an entropy compression (lossless). My test vector is a vector of 500 elements for example. Each element can take the value from 1 to 256. In my vector there will necessarily redundancies. And I can do compression with an arithmetic algorithm: the one proposed by: " Arithmetic coding for data compression I. Witten, R. Neal am\nd J. Cleary Communication of the ACM, 1987 Volume 30 Number 6 "
It works well but I would like to know is that there would not be another method more effective? Which would make it possible to have one with the same vector a better compression.
Ps: if you are interested I can share the part of the code that I modified and implement.
thank you.
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I'm trying to understand the different modulation techniques for the satellite communication
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Dear Mardi,
The different digital modulation techniques including the binary phase shift keying can be implemented using digital signal processors. The digital signal processor calcualtes the the required wave forms. In case of BPSK there are two possible implementations:
a base band implementation where logic one is represented by + V and the logic zero is represented by  -V , where V is any suitable scalar, and band pass representation where logic 1 is represented by V cos wct and the logic 0 is represented by - V cos wct.
Normally the base band implementation is the common method for DSP to save the computation and reduce the power consumption. If is necessary to implement BFSK in band pass form, it is advisable to select as low as possible carrier frequency wc.
For more information please refer to the link: https://cdn.intechopen.com/pdfs-wm/6846.pdf
Best wishes
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I have implemented Sum-product algorithm (SPA) in Octave for BPSK. I am having trouble with getting the equations for updating check nodes and variable nodes for QPSK. I could map with 64 QAM constellation diagram.
I have not studied coding theory or probability in detail. I had read about LDPC codes and decided to implement it in Octave.
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Thank you @Mohamed-Mourad Lafifi and @Ronald Mulinde. I would surely look into these materials.
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Is effect of cross polarization allowed in wireless communication?
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Hello Sajeed, I think a more deep understand of the concept can clarify the question. Besides you can add a context to analyze what is happening? Maybe this paper can help
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I did an antenna design on Sonnet EM simulator and wishes to view the far field on Matlab or any other possible means.
Any advice is highly appreciated.
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Thanks a lot  Siddhant, I now do my antenna designs in CST. 
I stupidly did one in Sonnet but wanted to see the far field. 
Thanks once more
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OFDM - Orthogonal frequency division multiplexing (orthogonal sub carriers) 
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Hi Kishan, I'm not sure if a understood your question.
After the antenna, your OFDM signal will be translated to the carrier frequency but will look like the same in time domain.. Depending on how you translate it you'll have twice the bandwidth.