you can use GAMIT or a simple gps software, you only need to check your results. check this software http://www.rtklib.com/rtklib_support.htm

Dear Prof. Tanguturi, Please refer to http://gage.upc.edu/gLAB which is an interactive educational multipurpose package to process and analyse GNSS data.Else there are number of online processing softwares are available. More information can be retrieved from http://www.navipedia.net/index.php/PPP_Systems.

Following software may b useful in this regard 

GAPS : The University of New Brunswick (UNB) developed the GPS Analysis and Positioning Software (GAPS).

GIPSY-OASIS, or GIPSY: the GNSS-Inferred Positioning System and Orbit Analysis Simulation Software package, developed by the Jet Propulsion Laboratory (JPL), and maintained by the Orbiter and Radio Metric Systems (ORMS) group.

Bernese Software: GPS/GLONASS post processing package developed by Astronomical and the Physical Institutes of the University of Bern, Switzerland.

I am a GPS expert and would like to answer your question but I am unclear as to its meaning and your application. As you know, each GPS satellite position (X, Y, Z, t) is very accurately characterized by its orbital parameters (ephemerides). Likewise, the position of the phase center of the antenna of a user GPS unit is accurately characterized by measuring the pseudo-ranges between user and at least 4 satellites and then using pseudo-range and satellite ephemerides to calculate (X, Y, Z, t) for the user. I am unfamiliar with Kai Borre MATLAB programmes but perhaps it does the same thing by using satellite, user, and applicable geometery to provide all the (X, Y, Z, t) information. Of course, you need to identify the satellites that were used in the navigation solution. Does it also compute GDOP?

Perhaps you are asking about how to validate the correctness and accuracy of the MATLAB simulation. It could be done by comparing with other programs attempting to do the same thing. Depending on your needs, you could consider doing the time and satellite geometry calculations yourself for a specific case. That is what we did for proof-of-correctness on the original NAVSTAR GPS program back in the 1970s. In real-life situations, we did not want to rely on multiple computer simulations, at least, not the first time!!

Good luck.

If I have understood correctly, I feel you are working on Software GPS Receivers. There are certain open source GPS Software Receivers available in the Internet along with freely available Software GPS simulators which can help in validation. You can use the Software GPS Simulator to generate a set of data and then the GPS Receiver to process that data and provide position. The same can be repeated for your GPS receiver and validated.

if you have any doubt regarding position of a particular GPS receiver, first you fixed a point and calculate position using a receiver than you replace it with another set of GPS receiver and calculate position. 

Thank you very much sir

Dear Sridher,

As suggested by Sampad, I also recommend you to use the gLAB tool suite. It can be run either Windows, Linux or MAC. It has the versatility to process in Standard Point Positioning (SPP) and Precise Point Positioning (PPP). It is very easy to use and you will have a reliable ground truth to which compare your current solutions.