Nowadays, we see a great evolution in communication systems and new methods of communication between people are created every day and manufacturers and developers face several problems like the environmental restrictions, safety factors, etc. put by governments and worldwide organizations. Electronics and communication manufactures face also other technical problems while developing new product like saving power, capacity, speed, etc. and they put their full efforts on how to enhance these factors. My book is trying to put solution in 2G/3G mobile communication by introducing the device to device system in 2G/3G mobile communication. The book discusses a new applied idea which will help in saving and increasing some of the previous mentioned factors.