Increasing Coverage of nRF51822 BLE module

[Vaio]

For some sort of geofencing application, we want to include the BLE module nRF51822 into a Base Station (BS), and a small mobile device (MS). The MS should detect the presence of a signal from the BS. If it is/is not present, certain actions are being triggered.

1.) While the maximum TxPower seems to be +4dBm, I heard that using an amplifier one can send up to the regulated limit of +20dBm.

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2.) Alternatively, I heard on the nRF51822 a custom protocol can be implemented. The design goal would be to reach maximum coverage (ideally, beyond walls inside a house).

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For both cases, the same questions arise:

Does anybody have experience / more infos on this? Mainly:

• what is the maximum coverage (in theory and practice)?
• what are the implications on power consumption (as this will be done in the BS, it shouldn't really matter)?

Thanks!

[Vaio]

Thanks Håkon,

in our setup the BS would be the transmitter (always advertising), and the MS the receiver (checking for the BS beacon's presence, e.g. once per minute). The MS doesn't even need to make an actual connection to the BS - it is sufficient to detect its presence.

The BS is connected to the wall, so no power problems there. The MS of course has very tight power requirements. Since we only check for presence e.g. once per minute, this should hopefully allow for multiple weeks of battery runtime.

Of course, coverage in buildings is hard to say. 200m LOS sounds promising however. Regarding decreasing the data rate: it seems for BLE, using 1 Mbps is the only valid datarate. Were u referring to a custom protocol (where 250kbps can be used)?

Other than decreasing the datarate, can sbdy think of any other means to extend the range? (could we equip the BS with a better antenna for instance, to get closer to the allowed +20 dBM?)

Best Rgds, Mike