How can I build Wireless sensor network using nRF51422

[Alok]

I have about 200-300 sensors, each requiring to send data at around 0.5-1Kbps to a central node (coordinator/master node), what will be the network configuration/topology using nRF51422 (or any other better suited Nordic IC) to send the data of all the sensors to the central node?

[ovrebekk]

Hi

If you want to support this many sensors sending that much data you need to implement some kind of timeslot mechanism, where each sensor gets a unique time in which to send data to the central node.

One way to do this is to have the central node send a beacon packet to all the sensors at a regular interval. Each sensor will have to be configured with a unique ID, and based on this ID each sensor can calculate a unique timeslot some time after the beacon packet was received. The central node will then switch to receive mode to pick up all the packets from the various sensors.

The beacon packet from the central node will have to be broadcast to all the sensors (ACK's disabled), while the packets sent from the sensors to the central could have ACK's enabled.

You probably want to use the micro ESB library as a basis, since it introduces less overhead than the standard ESB library available in the SDK:
https://github.com/NordicSemiconductor/nrf51-micro-esb

Bets regards
Torbjørn

[ovrebekk]

Any chip in the nRF24L, nRF51 or nRF52 series will work in proprietary mode, but at the moment the best choice is probably the nRF51822/nRF51422. The nRF51 series has been out for a while, is well supported and has the most examples available for it.
All the protocols supported by the Nordic devices use GFSK coding. The main difference is that you can use either 250kbps, 1Mbps or 2Mbps on-air bit rates in proprietary modes, while both ANT and BLE use 1 Mbps bit rate only.
The main strategy to handle interference from other sources (WiFi for instance) is to employ a frequency jumping scheme, where one can avoid interference by jumping to a different part of the 2.4GHz ISM band. One way to do that in a beacon scenario is to have the central send the beacon packet on multiple preconfigured channels, allowing the sensors to send their data on either one.