Table 3.

Comparison of communication cost.

Compared Protocols	Rounds of Communication	Overall Bandwidth of Communication	Bandwidth of Communication on SN
Reference [3]	3	832 bits	224 bits (GW to SN)
Reference [6]	3	928 bits	224 bits (GW to SN)
Reference [8]	8	1056 bits	352 bits (SN to GW) 160 bits (GW to SN) Total = 512 bits
Reference [10]	4	1600 bits	224 bits (SN to GW) 256 bits (GW to SN) Total = 480 bits
Reference [12]	4	2336 bits	480 bits (SN to GW) 352 bits (GW to SN) Total = 832 bits
Reference [18]	3	1376 bits	384 bits (SN to U) 544 bits (GW to SN) Total = 928 bits
Our improved protocol	3	1216 bits	448 bits (SN to U) 384 bits (GW to SN) Total = 832 bits