Digital audio transmission and reception

We need to design electronic circuits that makes digital audio transmission and reception ; so it will consists of two circuits : transmission circuit and reception circuit and will have the following specifications : 1-the audio sampling rate should be as high as possible 2- Each audio sample will be preceded by the transmitter identification and followed by the [Sample End indication] as shown in the attachments 3- The carrier frequency should be between 300MHz and 450MHz to avoid any interference with the FM stations 4- The circuits component should be available and at low costs as much as possible but not affect the circuit efficiency 5- If there is a usage of microcontroller, you should use pic18f2550, as it is suitable for our market and our pic programmers. 6- The transmission range should not be less than 25 meter 7- The designs should be accompanied by a simulation which prove and confirm its performance where it is possible to do 8- The design should be attached with complete explanation of: a- The circuit operation, b- Each component function and specification c- The time and frequency chart of the circuits 9- In the transmission circuit, there should be a push button, when it pressed, the transmission process starts; otherwise, the transmission circuit is in standby (the lowest power consumption) 10- Both the transmission and reception circuits will be portable, so their power supply should be suitable for that, so we should use a commonly used type and voltage batteries 11- The designer should tell us in full details how to change the carrier frequency in both sides (transmission and reception circuits) , for example : for 300MHz , 350MHz and 400MHz , how the entire both circuits including their antennas should be