Samir's Tech Blog

I go Open Source in Signal Processing

2009-08-31T14:04:00.000-07:00

Hi friends, I have just gone Open Source in the field of Signal Processing. Here is my first contribution, the topic of my previous blog post, now placed for all in MATLAB Central File Exchange.

Do visit there, download my codes, post your comments for improvement.

Binary Step-size LMS algorithm

2009-08-28T15:56:00.000-07:00

Any discussion of adaptive algorithms is worthless without the mention of world's most popular and easiest algorithm or the Least Mean Square Algorithm. It was given by Widrow and his first Ph.D student Ted Hoff.

I was trying out modifications of the LMS algorithm so that it will converge faster and the mean square error will also be smaller. Getting to one of the drawbacks of LMS, that it has only one controllable parameter "mu", the selection of whose value will be the most critical from design point of view w.r.t. convergence. So, I wanted to implement LMS in such a way that the step-size adapts to the error occurring in each iteration.

What I came out with is the Binary Step-size LMS algorithm.Here, we have two step sizes calculated from 2 values, delta and deviation. When the error increases from the previous value of error , step size is (delta+deviation). And when the error decreases from its previous value, step size is (delta-deviation). I implemented an adaptive equalizer using the BS-LMS algorithm. It was found that this converges faster than the LMS algorithm.

Moreover, considering the NLMS(Normalized LMS) algorithm where the step size is always (delta/energy of input signal), the NLMS converges faster than LMS. Putting the binary step size concept along with the NLMS, I found that the convergence rates of BS-NLMS and NLMS are nearly equal, however, the mean square error resulting from BS-NLMS has a smaller value as compared to that from NLMS.

In the above figure it may be noted that the mean square error for binary step size based algorithms is lesser than their one step size counterparts. For example, the MSE from BS-LMS is smaller than LMS and that of BS-NLMS is smaller than NLMS. This is advantageous when we would need to maintain high precision in our equalizers.

I have uploaded the required MATLAB files here.

Everyone is invited to please check my findings and post comments for improvement.

One of Netbeans Turorials

2009-08-25T13:39:00.000-07:00

Netbeans IDE is an open source environment for developing JAVA applications. I had put up a tutorial in Netbeans wiki about making a simple plugin there. Have a look at it

Here is the link to the plugin.

What I would deal with in this blog?

2009-08-25T13:31:00.000-07:00

Hi everyone, this is Samir Kumar Mishra, an Electronics and Telecommunication Engineer graduated from University College of Engineering, Burla, Orissa. Currently I'm working as a Software Engineer for Aricent Technologies.

I am particularly interested in Signal Processing, Communications and Adaptive Algorithms. Moreover, I do have possess an ok ok knowledge in programming languages like C, JAVA and MATLAB.

Here in this blog, I will deal with various technical issues and any innovative thing I find in due course of my research. Everyone is welcome to post comments so that I get a chance to improve myself with each post that I put up.

Cheers,
Samir