Most Reliable, Least Expensive Wireless Control of PIC or Arduino

[EPAIII]

Be considerate as I am somewhat new to all of this. After all, that is why I am asking.

I would like to have a simple, wireless control that will trigger a PIC or Arduino or some other programmable device to do something simple. That something could be described just as initiating a simple relay closure. The rest could be done in the programming. The wireless link ONLY needs to start the sequence.

This needs to operate over a range of my house but, unfortunately the PIC or Arduino would be in a rear room, not centrally located. And it is a somewhat big house so there could be five or six walls between the transmitter and the receiver. I would not like to use Wifi as that is too unreliable and if possible I may want to transmit some data in the other direction but that is optional. I would like to use a cell phone as the transmitting device. I have an Android type cell.

What are my options and how would I learn more about them? Something with existing software for the cell phone and existing libraries for the PIC/Arduino end would be nice as I would need to learn the coding language and the less I have to write, the better.

If I have left out any needed details, please let me know; I have tried to keep this as short as possible.

[DavidAlfa]

Have you considered using sub-GHz transceivers ?(315MHz, 433MHz, 868MHz, etc).
These bands can reach much larger distances than Wifi/BT with the same power, they can pass through almost anything except soviet bunkers.
Check the nRF905, uses SPI interface, handles the complex part keeping it simple.
You only need to adjust few registers (they seem pretty simple).
- Config few settings like the CRC and your receiver address (configurable to 1 and 4-byte length).
- When transmitting, set the dest address, the payload size(1-32 bytes), send the data, enable TX and wait for the transfer complete signal.
- It handles everything (CRC, retransmission...).
- A receiver matching the address will strip the data from the packet and set the data ready signal to let the mcu know there's new data.

Looks really easy and powerful, the modules are cheap at Aliexpress.
https://infocenter.nordicsemi.com/pdf/nRF905_PS_v1.5.pdf

There're others, like SX1212, Si4430/31/32, CC1101...

[Leiothrix]

You want to use a phone as the transmitter, that basically leaves you with WiFi or Bluetooth.

There are plenty of WiFi or Bluetooth "smart"  plug-in switches around, I would suggest one of those would probably suit your needs more than anything else.  If WiFi doesn't reach get some repeaters.

You have not stated what you're trying to do overall, so it's a bit hard to recommend anything too much.

[rpiloverbd]

If your house has wifi internet, then ESP8266 will be the best option. You will be able to control that from your mobile phone. Using the HC-05 Bluetooth module with Arduino can be an option too. But those have a range of only 10m. Not sure if that will cover your whole house. Another option is to use a Tx and Rx pair of  NRF24L01 RF Board.