Bluetooth LE firmware development on NRF51822

Hi! In short we need to be able to identify person to person contact in proximity (only need to detect whether they are in close contact or not). And we chose to use beacons based on BLE. So each Bean can receive and advertise packets from other beans in order to "measure" how closer they are. We use RSSI level of received packets as a measurement. Each bean supports Observer and Broadcaster roles. No need for connections. Please look at the attached image what we are trying to achieve. The requirements are for the firmware: - final solution has to run on nRF51822 Bluetooth Smart Beacon Kit or nRF51 usb Dongle (PCA10031); - s130 softdevice SDK is preferred but not limited; - Keil or gcc; - code has to be clean and well documented; - we will test final deployment on multiple beans where each of them will be connected to PC in order to output received packets RSSI via uart to terminal. We are looking for someone who has extensive experience with nRF51 development and also with BLE stack (custom advertising packets).