i'm doing a project on nurse call device.. consist of transmitter and receivers. each patient will have their own transmitter but at the nurse call station there's only 1 receiver getting the signal.. however we encounter problem when two transmitter send signal at the same time.. both of the signal will be rejected.. i need to know if anyone out here know any multi-channel RF receiver. and also i might need help with interfacing the 8051 with the receiver.
Hans-Bernhard is right - this has nothing to do with Keil tools, nor even particularly much with your choice of processor. However, why don't you look at devices intended, eg, for remote-control of car central locking? Microchip do them - see if they have a discussion forum at their website, or speak to your local rep/distributor.
Nordic (http://www.keil.com/dd/cl/Nordic/8051.htm) and ChipCon (http://www.keil.com/dd/cl/Chipcon/8051.htm) are offering RF chips (as they are used in Car Keys) based on 8051 technology. These companies provide reference designs that you may re-use for your projects.