error detection
	parity check code, single bit, extendable to multiple bits
	crc, going over crc process, need polynomial, divide data by result of polynomial, binary long division
		tack remainder on to data, on receipt, division is performed, if there is an error, there will be a remainder
		polynomial codes
			i(x) = iv(k-1)*x^(k-1)...iv(1)*x + iv(0)
			for info = 1001, g(x) -> x^3 + 1
			i(x) is data polynomial
			g(x) is generated polynomial
			sender: x^(n-k)i(x)/g(x), get q(x) and r(x), x^(n-k)*i(x) + r(x) transmitted
			receiver: does same division, expects remainder of 0
	ARQ - stop and wait
	a	b
	 ->f0
	  NAK<-
	 ->f0
	  ACK1<-
	p = probability of link corrupting frame
	worst case, link is always broken, always retry send frame 0, p=1
	best case, link perfect, no retries, p=0