Array Signal Processing

Methods used to estimate the Angles of Arrival (AoA) of signals at a base station can be generally classified into two categories.

1. Maximum Likelihood Based Algorithms
2. Subspace Estimation Based Algorithms

MUSIC (Multiple Signal Classification) is one of the methods based on subspace estimation that can be used to estimate the angles of arrival of multiple impinging signals. In this method array of antenna elements is used, all the impinging wave fronts are recorded on all antennas and processed to find out the angles of arrival. Maximum number of impinging wave fronts that can distinguished using this method is given by M-1, where M is the number of elements in the antenna array. The reason is that this method is based on Noise Subspace and we need at least one vector for noise subspace to exist, which is made sure when the number of impinging wave fronts is at least one less than the number of antenna elements in the array.

Antenna Tip of the Day!

A radome becomes completely reflection-less if its thickness is half the wavelength.

GPRS and EGPRS

As per The European Telecommunications Standards Institute (ETSI), GPRS has 4 coding schemes namely CS-1, CS-2, CS-3 and CS-4. CS-1 offers lowest data rate with highest data protection whereas CS-4 has highest data rates with minimal protection of data. E-GPRS uses 8-PSK modulation (transmits 3 bits per symbol) scheme and consequently has 9 coding schemes MCS-1 to MCS-9 in order of highest to lowest data protection and lowest to highest data speeds.

Antenna Tip of the Day!

When a Right Handed Circularly Polarized (RHCP) wave strikes a plane surface, it becomes LHCP on reflection. In case when it strikes a corner reflector, it retains its polarization (due to dual reflection).

Team Management

"Coutesy www.managementstudyguide.com" Management is essential in every walk of life. Even what we eat should be managed. You just can’t put anything in your mouth. One needs to be cautious. In the same way, a team must be managed effectively to expect the best from the team members. The team leader plays an essential role in managing his team well. ■For effective team management, it is important that the team leader is more of a mentor to his team members rather than just being a strict boss. Understand your team members well. Gone are the days when people used to fear their bosses. Now a days employees share a healthy relation with their superiors and the comfort level has increased to a large extent. Don’t impose things on them. ■Ensure that each and every team member willingly participates in team discussions. Debates are important, but make sure you don’t end up fighting with each other. Suggestions must be invited from all and do not discuss issues separately with individuals. Call every one on an open forum and formulate strategies keeping in mind every body’s inputs. Poilcies should be made best suited to all. The objective of the team must be clearly set and circulated among all the team members. Everyone should be aware of his roles and responsibilities in the team. ■Communication among the team members must be clear and transparent for an effective team management. Every team member should get the same information and should have an easy access to the superiors in case of any query. ■The team members must not pass on any information to anyone outside the team. Learn to keep things to yourself. It is unethical to share your professional secrets with others. Don’t leak information or any confidential data. ■The team members must be motivated on a regular basis. Appreciation is a must. If any team member has performed extraordinarily, do give him a pat on his back. Performance appraisals, perks, incentives, trophies, prizes are all instrumental in motivating the team members to perform even better the next time. Avoid criticizing any of your team members. ■Loose talks, blame games, dirty politics should find no place in the team. They spoil the environment and people lose interest in their work and organization. If you come to know anything about someone, it’s better to discuss with him face to face, else ignore. ■It is easy to create a team but it is actually difficult to bind the team members together and even make them work. Team management techniques help in strengthening the bond among the employees and creating an environment where they can trust each other. People actually become friends and start working together as a result of team management activities.

Antenna Tip of the Day!

Circularly polarized antennas find their application in ground stations for receiving signals from bodies having arbitrary motion and mounted with linearly polarized antennas. This is done so that the maximum polarization loss at any instant doesn't exceed 3 dB.

Antenna Tilts

There are two types of antenna tilts used in telecom networks:

1. Electrical Tilt
2. Mechanical Tilt

Electrical Tilt has a uniform affect on the main lobe whereas Mechanical Tilt causes side lobe effect when it is given a down tilt. The effect can be demonstrated easily on Coverage Planning tools.