Suppose I use my phone as hotspot and I connect my Ipad to this on which I trade , how much latency this causes ? the reason I dont put my sim card for internet in my iPad is that the provider does not allow me to create a hotspot on my ipad
Hard to tell. But you can test it out by connecting your iPad to your hotspot and by doing a ping test to a server near to where your brokers servers are located.
then I should do different ping test from my phone and ipad to see if the average value has any serious difference ?
You are wanting to trade from your IPAD? I travel and in other countries I just buy a local SIM card and put it in my IPAD. Then I have internet. I can then trade off a laptop using the IPAD as the hotspot. Or trade off the IPAD directly on a web based trading platform. When in the USA I have a travel modem and a telephone and plan that is wired to it. The cell phone picks up the signal and gives it to the modem which broadcast it wirelessly. I can watch TV trade on my laptop at the same time. My wife can also watch TV on another TV. I pay $45.00 a month for this service. I can use the modem in the car, truck, or motorhome. I have found very few spots where the signal doesn't work but it is very rare. I travel in the motorhome through various states in the USA and by far most everywhere I go I have coverage. The modem will work off twelve volts cigarette lighter in a vehicle or 110 volts AC. It also keeps the phone connected to it charged. So, my wife can drive while I scalp as we race down the interstate. If in the motorhome when we get to an RV park I don't bother to hook up to their internet if they have it. I just use my modem plugged into the 110 volts or cigarette lighter. I am a scalper sometimes seconds or minutes in a trade and latency doesn't seem to bother me. I can scalp just fine scalping ES, NQ..etc. But I am not scalping for just 1 tick.
If you travel a lot, as I do, you should consider using Google Fi cellphone service (Yes Google has a cellphone service). My phone works in 200 different countries, and Google is the only cellphone service I know of that encourages you to use your phone as a hotspot.
I would argue that for retail traders it does not make much sense to talk about latency. In the time it takes to move your fingers, high frequency traders's algorithms, colocation, proprietary cables, laser etc. have already cleaned the table in terms of speed. Find your edge in something other than speed.