A Reliable Data Transmission Model for IEEE 802.15.4e Enabled Wireless Sensor Network under WiFi Interference

. 2017 Jun 7;17(6):1320. doi: 10.3390/s17061320

Algorithm 1 The modified CSMA/CA mechanism

Require:
$N B = 0, R_{t r n s} = 0, T_{c c a} = 8 s y m b o l s$ , packet duration $T_{p k t}$ ;
Ensure:
Transmission success/failure.
1:
Listen to the channel;
2:
if (Beacon not received) then
3:
Wait for beacon;
4:
else
5:
$C W_{i} = C W_{M A X} * \frac{B_{i, M a x} - B_{i, n o w}}{B_{i, M a x}}$ ;
6:
$R_{b c k}$ = $r a n d o m (0, C W_{i})$ ;
7:
if $(R_{t i m e} \leq R_{b c k} + T_{c c a} + T_{p k t})$ then
8:
$N B = N B + 1$ ;
9:
if $(N B > N B_{m a x})$ then
10:
Stop due to channel access failure;
11:
else
12:
go to step 1;
13:
end if
14:
else
15:
Access channel after $R_{b c k}$ duration;
16:
if (channel busy) then
17:
Switch to power saving mode for $r a n d o m (0, T_{p k t})$ duration;
18:
$N B = N B + 1$ ;
19:
if $(N B > N B_{m a x})$ then
20:
Stop due to channel access failure;
21:
else
22:
go to step 5;
23:
end if
24:
else
25:
Start transmission and wait for ACK;
26:
if (ACK is not received) then
27:
$R_{t r n s} = R_{t r n s} + 1$ ;
28:
if $R_{t r n s} \leq M A X_{R_{t r n s}}$ then
29:
Wait for next retransmission period and go to step 5;
30:
else
31:
Stop due to transmission failure;
32:
end if
33:
end if
34:
end if
35:
end if
36:
end if