A Novel IEEE 802.15.4e DSME MAC for Wireless Sensor Networks

. 2017 Jan 16;17(1):168. doi: 10.3390/s17010168

Algorithm 3 New channel access scheme.

Require:

N B = 0, B E = m a c M i n B E, R T = 0, σ = 20 s y m b o l s, T_{C C A} = 8 s y m b o l s

C C B = 0 o r 1

and packet duration time

T_{D}

Ensure: Transmission success/failure.

1:
$Δ = 2 \times T_{C C A} + 2 \times σ + T_{D}$
2:
if Beacon received then
3:
Calculate the $C A P_{i n d e x}$ and wakeup at start of the $C A P_{i n d e x}$ ;
4:
else
5:
Wait for beacon;
6:
end if
7:
Generate a random backoff time $R_{b}$ = $r a n d o m (0, 2^{B E - 1}) \times σ$ ;
8:
if $((R_{C A P} \leq Δ)$ or $C C B = 0)$ then
9:
Wait for next superframe and go to step 2;
10:
else
11:
Perform CCA1 after $R_{b}$ duration;
12:
if Channel found busy then
13:
Switch to sleep state for the $r a n d o m (0, T_{D})$ and go to step 30;
14:
else
15:
Wait for $2 σ$ and perform CCA2;
16:
if Channel found busy then
17:
Switch to sleep state for $T_{D}$ and go to step 30;
18:
else
19:
Start transmission;
20:
if Transmission failure then
21:
$R T = R T + 1$ ;
22:
if $R T$ ≤ $M A X_{R T}$ then
23:
Go to step 7;
24:
else
25:
Transmission failure;
26:
end if
27:
end if
28:
end if
29:
end if
30:
$N B = N B + 1$ , $B E = m i n (B E + 1, m a c M a x B E)$ ;
31:
if $(N B > M A X_{N B})$ then
32:
Transmission failure;
33:
else
34:
Go to step 7;
35:
end if
36:
end if