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dq.py
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dq.py
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#!/usr/bin/env python2
# -*- coding: utf-8 -*-
"""
SYNOPSIS:
./loraDir.py <nodes> <avgsend> <experiment> <simtime> [collision]
DESCRIPTION:
nodes
number of nodes to simulate
avgsend
average sending interval in milliseconds
experiment
experiment is an integer that determines with what radio settings the
simulation is run. All nodes are configured with a fixed transmit power
and a single transmit frequency, unless stated otherwise.
0 use the settings with the the slowest datarate (SF12, BW125, CR4/8).
1 similair to experiment 0, but use a random choice of 3 transmit
frequencies.
2 use the settings with the fastest data rate (SF6, BW500, CR4/5).
3 optimise the setting per node based on the distance to the gateway.
4 use the settings as defined in LoRaWAN (SF12, BW125, CR4/5).
5 similair to experiment 3, but also optimises the transmit power.
simtime
total running time in milliseconds
collision
set to 1 to enable the full collision check, 0 to use a simplified check.
With the simplified check, two messages collide when they arrive at the
same time, on the same frequency and spreading factor. The full collision
check considers the 'capture effect', whereby a collision of one or the
OUTPUT
The result of every simulation run will be appended to a file named expX.dat,
whereby X is the experiment number. The file contains a space separated table
of values for nodes, collisions, transmissions and total energy spent. The
data file can be easily plotted using e.g. gnuplot.
"""
import simpy
import random
import numpy as np
import math
import sys
import matplotlib.pyplot as plt
import os
# turn on/off graphics
graphics = 0
# do the full collision check
full_collision = False
# experiments:
# 0: packet with longest airtime, aloha-style experiment
# 0: one with 3 frequencies, 1 with 1 frequency
# 2: with shortest packets, still aloha-style
# 3: with shortest possible packets depending on distance
# this is an array with measured values for sensitivity
# see paper, Table 3
sf7 = np.array([7,-126.5,-124.25,-120.75])
sf8 = np.array([8,-127.25,-126.75,-124.0])
sf9 = np.array([9,-131.25,-128.25,-127.5])
sf10 = np.array([10,-132.75,-130.25,-128.75])
sf11 = np.array([11,-134.5,-132.75,-128.75])
sf12 = np.array([12,-133.25,-132.25,-132.25])
#
# check for collisions at base station
# Note: called before a packet (or rather node) is inserted into the list
def checkcollision(packet):
col = 0 # flag needed since there might be several collisions for packet
processing = 0
for i in range(0,len(packetsAtBS)):
if packetsAtBS[i].packet.processed == 1:
processing = processing + 1
if (processing > maxBSReceives):
print "too long:", len(packetsAtBS)
packet.processed = 0
else:
packet.processed = 1
if packetsAtBS:
print "CHECK node {} (sf:{} bw:{} freq:{:.6e}) others: {}".format(
packet.nodeid, packet.sf, packet.bw, packet.freq,
len(packetsAtBS))
for other in packetsAtBS:
if other.nodeid != packet.nodeid:
print ">> node {} (sf:{} bw:{} freq:{:.6e})".format(
other.nodeid, other.packet.sf, other.packet.bw, other.packet.freq)
# simple collision
if frequencyCollision(packet, other.packet) \
and sfCollision(packet, other.packet):
if full_collision:
if timingCollision(packet, other.packet):
# check who collides in the power domain
c = powerCollision(packet, other.packet)
# mark all the collided packets
# either this one, the other one, or both
for p in c:
p.collided = 1
if p == packet:
col = 1
else: #other collided packet
if other not in q:
q.append(other)
else:
# no timing collision, all fine
pass
else:
packet.collided = 1
other.packet.collided = 1 # other also got lost, if it wasn't lost already
col = 1
return col
return 0
#
# frequencyCollision, conditions
#
# |f1-f2| <= 120 kHz if f1 or f2 has bw 500
# |f1-f2| <= 60 kHz if f1 or f2 has bw 250
# |f1-f2| <= 30 kHz if f1 or f2 has bw 125
def frequencyCollision(p1,p2):
if (abs(p1.freq-p2.freq)<=120 and (p1.bw==500 or p2.freq==500)):
print "frequency coll 500"
return True
elif (abs(p1.freq-p2.freq)<=60 and (p1.bw==250 or p2.freq==250)):
print "frequency coll 250"
return True
else:
if (abs(p1.freq-p2.freq)<=30):
print "frequency coll 125"
return True
#else:
print "no frequency coll"
return False
def sfCollision(p1, p2):
if p1.sf == p2.sf:
print "collision sf node {} and node {}".format(p1.nodeid, p2.nodeid)
# p2 may have been lost too, will be marked by other checks
return True
print "no sf collision"
return False
def powerCollision(p1, p2):
powerThreshold = 6 # dB
print "pwr: node {0.nodeid} {0.rssi:3.2f} dBm node {1.nodeid} {1.rssi:3.2f} dBm; diff {2:3.2f} dBm".format(p1, p2, round(p1.rssi - p2.rssi,2))
if abs(p1.rssi - p2.rssi) < powerThreshold:
print "collision pwr both node {} and node {}".format(p1.nodeid, p2.nodeid)
# packets are too close to each other, both collide
# return both packets as casualties
return (p1, p2)
elif p1.rssi - p2.rssi < powerThreshold:
# p2 overpowered p1, return p1 as casualty
print "collision pwr node {} overpowered node {}".format(p2.nodeid, p1.nodeid)
return (p1,)
print "p1 wins, p2 lost"
# p2 was the weaker packet, return it as a casualty
return (p2,)
def timingCollision(p1, p2):
# assuming p1 is the freshly arrived packet and this is the last check
# we've already determined that p1 is a weak packet, so the only
# way we can win is by being late enough (only the first n - 5 preamble symbols overlap)
# assuming 8 preamble symbols
Npream = 8
# we can lose at most (Npream - 5) * Tsym of our preamble
Tpreamb = 2**p1.sf/(1.0*p1.bw) * (Npream - 5)
# check whether p2 ends in p1's critical section
p2_end = p2.addTime + p2.rectime
p1_cs = env.now + Tpreamb
print "collision timing node {} ({},{},{}) node {} ({},{})".format(
p1.nodeid, env.now - env.now, p1_cs - env.now, p1.rectime,
p2.nodeid, p2.addTime - env.now, p2_end - env.now
)
if p1_cs < p2_end:
# p1 collided with p2 and lost
print "not late enough"
return True
print "saved by the preamble"
return False
# this function computes the airtime of a packet
# according to LoraDesignGuide_STD.pdf
#
def airtime(sf,cr,pl,bw):
H = 0 # implicit header disabled (H=0) or not (H=1)
DE = 0 # low data rate optimization enabled (=1) or not (=0)
Npream = 8 # number of preamble symbol (12.25 from Utz paper)
if bw == 125 and sf in [11, 12]:
# low data rate optimization mandated for BW125 with SF11 and SF12
DE = 1
if sf == 6:
# can only have implicit header with SF6
H = 1
Tsym = (2.0**sf)/bw
Tpream = (Npream + 4.25)*Tsym
print "sf", sf, " cr", cr, "pl", pl, "bw", bw
payloadSymbNB = 8 + max(math.ceil((8.0*pl-4.0*sf+28+16-20*H)/(4.0*(sf-2*DE)))*(cr+4),0)
Tpayload = payloadSymbNB * Tsym
return Tpream + Tpayload
#
# this function creates a node
#
class myNode():
def __init__(self, nodeid, bs, period, packetlen):
self.nodeid = nodeid
self.period = period
self.bs = bs
self.x = 0
self.y = 0
# this is very complex prodecure for placing nodes
# and ensure minimum distance between each pair of nodes
found = 0
rounds = 0
global nodes
while (found == 0 and rounds < 100):
a = random.random()
b = random.random()
if b<a:
a,b = b,a
posx = b*maxDist*math.cos(2*math.pi*a/b)+bsx
posy = b*maxDist*math.sin(2*math.pi*a/b)+bsy
if len(nodes) > 0:
for index, n in enumerate(nodes):
dist = np.sqrt(((abs(n.x-posx))**2)+((abs(n.y-posy))**2))
if dist >= 10:
found = 1
self.x = posx
self.y = posy
else:
rounds = rounds + 1
if rounds == 100:
print "could not place new node, giving up"
exit(-1)
else:
print "first node"
self.x = posx
self.y = posy
found = 1
self.dist = np.sqrt((self.x-bsx)*(self.x-bsx)+(self.y-bsy)*(self.y-bsy))
print('node %d' %nodeid, "x", self.x, "y", self.y, "dist: ", self.dist)
self.packet = myPacket(self.nodeid, packetlen, self.dist)
self.sent = 0
# graphics for node
global graphics
if (graphics == 1):
global ax
ax.add_artist(plt.Circle((self.x, self.y), 2, fill=True, color='blue'))
#
# this function creates a packet (associated with a node)
# it also sets all parameters, currently random
#
class myPacket():
def __init__(self, nodeid, plen, distance):
global experiment
global Ptx
global gamma
global d0
global var
global Lpld0
global GL
self.nodeid = nodeid
self.txpow = Ptx
# randomize configuration values
self.sf = random.randint(6,12)
self.cr = random.randint(1,4)
self.bw = random.choice([125, 250, 500])
# for certain experiments override these
if experiment==1 or experiment == 0:
self.sf = 12
self.cr = 4
self.bw = 125
# for certain experiments override these
if experiment==2:
self.sf = 6
self.cr = 1
self.bw = 500
# lorawan
if experiment == 4:
self.sf = 12
self.cr = 1
self.bw = 125
# for experiment 3 find the best setting
# OBS, some hardcoded values
Prx = self.txpow ## zero path loss by default
# log-shadow
Lpl = Lpld0 + 10*gamma*math.log10(distance/d0)
print "Lpl:", Lpl
Prx = self.txpow - GL - Lpl
if (experiment == 3) or (experiment == 5):
minairtime = 9999
minsf = 0
minbw = 0
print "Prx:", Prx
for i in range(0,6):
for j in range(1,4):
if (sensi[i,j] < Prx):
self.sf = int(sensi[i,0])
if j==1:
self.bw = 125
elif j==2:
self.bw = 250
else:
self.bw=500
at = airtime(self.sf, 1, plen, self.bw)
if at < minairtime:
minairtime = at
minsf = self.sf
minbw = self.bw
minsensi = sensi[i, j]
if (minairtime == 9999):
print "does not reach base station"
exit(-1)
print "best sf:", minsf, " best bw: ", minbw, "best airtime:", minairtime
self.rectime = minairtime
self.sf = minsf
self.bw = minbw
self.cr = 1
if experiment == 5:
# reduce the txpower if there's room left
self.txpow = max(2, self.txpow - math.floor(Prx - minsensi))
Prx = self.txpow - GL - Lpl
print 'minsesi {} best txpow {}'.format(minsensi, self.txpow)
# transmission range, needs update XXX
self.transRange = 150
self.pl = plen
self.symTime = (2.0**self.sf)/self.bw
self.arriveTime = 0
self.rssi = Prx
# frequencies: lower bound + number of 61 Hz steps
self.freq = 860000000 + random.randint(0,2622950)
# for certain experiments override these and
# choose some random frequences
if experiment == 1:
self.freq = random.choice([860000000, 864000000, 868000000])
else:
self.freq = 860000000
print "frequency" ,self.freq, "symTime ", self.symTime
print "bw", self.bw, "sf", self.sf, "cr", self.cr, "rssi", self.rssi
self.rectime = airtime(self.sf,self.cr,self.pl,self.bw)
print "rectime node ", self.nodeid, " ", self.rectime
# denote if packet is collided
self.collided = 0
self.processed = 0
#
# main discrete event loop, runs for each node
# a global list of packet being processed at the gateway
# is maintained
#
def transmit(env,node):
last_wait = 0
global crq
global dtq
while True:
#yield env.timeout(random.expovariate(1.0/float(node.period)))
wait_time = math.ceil(random.expovariate(1.0/float(node.period)))
#print 'Wait_time:', wait_time
yield env.timeout(wait_time)
while crq:
yield env.timeout(1000)
wait_time = wait_time + 1
last_wait = last_wait + wait_time
# time sending and receiving
# packet arrives -> add to base station
#node.packet.addTime = env.now
node.packet.addTime = last_wait
#node.packet.addTime = math.floor(env.now)
if not dtq: #if dtq is empty
node.packet.type = "ARS_DATA"
node.packet.ars = random.randint(1,3)
elif node.nodeid == dtq[0]:
node.packet.type = "DATA"
node.packet.ars = 0
else:
node.packet.type = "ARS"
node.packet.ars = random.randint(1,3)
if node.packet.type == "ARS_DATA" or node.packet.type == "DATA":
node.sent = node.sent + 1
if (node in packetsAtBS):
print "ERROR: packet already in"
else:
sensitivity = sensi[node.packet.sf - 7, [125,250,500].index(node.packet.bw) + 1]
if node.packet.rssi < sensitivity:
print "node {}: packet will be lost".format(node.nodeid)
node.packet.lost = True
else:
node.packet.lost = False
if node.packet.type == "ARS_DATA":
# adding packet if no collision
if (checkcollision(node.packet)==1):
node.packet.collided = 1
q.append(node)
yield env.timeout(1000)
while not ((crq and node.nodeid in crq[0]) or (dtq and node.nodeid == dtq[0])):
yield env.timeout(1000)
if (crq and node.nodeid in crq[0]):
transmit_ARS_wait(node)
elif node.nodeid == dtq[0]:
transmit_DATA(node)
#print 'Q:', q
else:
node.packet.collided = 0
packetsAtBS.append(node)
#node.packet.addTime = env.now
####print 'Node {} transmit time: {}'.format(node.nodeid, node.packet.addTime)
elif node.packet.type == "ARS" and node.packet.lost == False:
q.append(node)
#print 'Q:', q
####print "Exit"
####exit(-1)
yield env.timeout(1000)
#print node.nodeid
#print crq
#print dtq
while not ((crq and node.nodeid in crq[0]) or (dtq and node.nodeid == dtq[0])):
yield env.timeout(1000)
if (crq and node.nodeid in crq[0]):
transmit_ARS_wait(node)
elif node.nodeid == dtq[0]:
transmit_DATA(node)
yield env.timeout(node.packet.rectime)
if node.packet.lost:
global nrLost
nrLost += 1
if node.packet.collided == 1:
global nrCollisions
nrCollisions = nrCollisions +1
#added here
global ars_data_collision
if node.packet.type == "ARS_DATA":
ars_data_collision = ars_data_collision + 1
if node.packet.collided == 0 and not node.packet.lost:
global nrReceived
nrReceived = nrReceived + 1
if node.packet.processed == 1:
global nrProcessed
nrProcessed = nrProcessed + 1
# complete packet has been received by base station
# can remove it
if (node in packetsAtBS):
packetsAtBS.remove(node)
# reset the packet
node.packet.collided = 0
node.packet.processed = 0
node.packet.lost = False
def transmit_ARS_wait(node):
global crq
global dtq
node.packet.type = "ARS"
node.packet.ars = random.randint(1,3)
q.append(node)
#print 'Q:', q
yield env.timeout(1000)
while not ((crq and node.nodeid in crq[0]) or node.nodeid == dtq[0]):
yield env.timeout(1000)
if (crq and node.nodeid in crq[0]):
transmit_ARS_wait(node)
elif node.nodeid == dtq[0]:
transmit_DATA(node)
def transmit_DATA(node):
node.packet.type = "DATA"
node.packet.ars = 0
node.sent = node.sent + 1
global nrReceived
nrReceived = nrReceived + 1
global nrProcessed
nrProcessed = nrProcessed + 1
node.packet.collided = 0
node.packet.processed = 0
node.packet.lost = False
def q_handler(env):
yield env.timeout(500)
global crq
global dtq
global q
while True:
minislot1 = []
minislot2 = []
minislot3 = []
if crq:
crq.pop(0)
if dtq:
dtq.pop(0)
for node in q:
if node.packet.ars == 1:
minislot1.append(node.nodeid)
elif node.packet.ars == 2:
minislot2.append(node.nodeid)
elif node.packet.ars == 3:
minislot3.append(node.nodeid)
q.remove(node)
if len(minislot1) == 0:
pass
elif len(minislot1) == 1:
dtq.append(node.nodeid)
elif len(minislot1) > 1:
crq.append(minislot1)
####print 'CRQ:', crq
if len(minislot2) == 0:
pass
elif len(minislot2) == 1:
dtq.append(node.nodeid)
elif len(minislot2) > 1:
crq.append(minislot2)
####print 'CRQ:', crq
if len(minislot3) == 0:
pass
elif len(minislot3) == 1:
dtq.append(node.nodeid)
elif len(minislot3) > 1:
crq.append(minislot3)
####print 'CRQ:', crq
if env.now < 100000:
global ars_data_collision_initial
global ars_data_collision
ars_data_collision_initial = ars_data_collision
print 'CRQ:', crq
print 'DTQ:', dtq
yield env.timeout(1000)
#
# "main" program
#
# get arguments
if len(sys.argv) >= 5:
nrNodes = int(sys.argv[1])
avgSendTime = int(sys.argv[2])
experiment = int(sys.argv[3])
simtime = int(sys.argv[4])
if len(sys.argv) > 5:
full_collision = bool(int(sys.argv[5]))
print "Nodes:", nrNodes
print "AvgSendTime (exp. distributed):",avgSendTime
print "Experiment: ", experiment
print "Simtime: ", simtime
print "Full Collision: ", full_collision
else:
print "usage: ./loraDir <nodes> <avgsend> <experiment> <simtime> [collision]"
print "experiment 0 and 1 use 1 frequency only"
exit(-1)
#Global value of the CRQ and DTQ
crq = []
dtq = []
q = []
ars_data_collision = 0
# global stuff
#Rnd = random.seed(12345)
nodes = []
packetsAtBS = []
env = simpy.Environment()
# maximum number of packets the BS can receive at the same time
maxBSReceives = 8
# max distance: 300m in city, 3000 m outside (5 km Utz experiment)
# also more unit-disc like according to Utz
bsId = 1
nrCollisions = 0
nrReceived = 0
nrProcessed = 0
nrLost = 0
Ptx = 14
gamma = 2.08
d0 = 40.0
var = 0 # variance ignored for now
Lpld0 = 127.41
GL = 0
sensi = np.array([sf7,sf8,sf9,sf10,sf11,sf12])
if experiment in [0,1,4]:
minsensi = sensi[5,2] # 5th row is SF12, 2nd column is BW125
elif experiment == 2:
minsensi = -112.0 # no experiments, so value from datasheet
elif experiment in [3,5]:
minsensi = np.amin(sensi) ## Experiment 3 can use any setting, so take minimum
Lpl = Ptx - minsensi
print "amin", minsensi, "Lpl", Lpl
maxDist = d0*(math.e**((Lpl-Lpld0)/(10.0*gamma)))
print "maxDist:", maxDist
# base station placement
bsx = maxDist+10
bsy = maxDist+10
xmax = bsx + maxDist + 20
ymax = bsy + maxDist + 20
# prepare graphics and add sink
if (graphics == 1):
plt.ion()
plt.figure()
ax = plt.gcf().gca()
# XXX should be base station position
ax.add_artist(plt.Circle((bsx, bsy), 3, fill=True, color='green'))
ax.add_artist(plt.Circle((bsx, bsy), maxDist, fill=False, color='green'))
for i in range(0,nrNodes):
# myNode takes period (in ms), base station id packetlen (in Bytes)
# 1000000 = 16 min
node = myNode(i,bsId, avgSendTime,20)
nodes.append(node)
env.process(transmit(env,node))
env.process(q_handler(env))
#prepare show
if (graphics == 1):
plt.xlim([0, xmax])
plt.ylim([0, ymax])
plt.draw()
plt.show()
# start simulation
env.run(until=simtime)
# print stats and save into file
print "nrCollisions ", nrCollisions
# compute energy
# Transmit consumption in mA from -2 to +17 dBm
TX = [22, 22, 22, 23, # RFO/PA0: -2..1
24, 24, 24, 25, 25, 25, 25, 26, 31, 32, 34, 35, 44, # PA_BOOST/PA1: 2..14
82, 85, 90, # PA_BOOST/PA1: 15..17
105, 115, 125] # PA_BOOST/PA1+PA2: 18..20
# mA = 90 # current draw for TX = 17 dBm
V = 3.0 # voltage XXX
sent = sum(n.sent for n in nodes)
energy = sum(node.packet.rectime * TX[int(node.packet.txpow)+2] * V * node.sent for node in nodes) / 1e6
print "energy (in J): ", energy
print "sent packets: ", sent
print "collisions: ", nrCollisions
print "received packets: ", nrReceived
print "processed packets: ", nrProcessed
print "lost packets: ", nrLost
# data extraction rate
der = (sent-nrCollisions)/float(sent)
print "DER:", der
der1 = (nrReceived)/float(sent)
print "DER method 2:", der1
# this can be done to keep graphics visible
if (graphics == 1):
raw_input('Press Enter to continue ...')
# save experiment data into a dat file that can be read by e.g. gnuplot
# name of file would be: exp0.dat for experiment 0
fname = "exp" + str(experiment) + ".dat"
print fname
if os.path.isfile(fname):
res = "\n" + str(nrNodes) + " " + str(nrCollisions) + " " + str(sent) + " " + str(energy) + " " + str(der)
else:
res = "#nrNodes nrCollisions nrTransmissions OverallEnergy\n" + str(nrNodes) + " " + str(nrCollisions) + " " + str(sent) + " " + str(energy) + " " + str(der)
with open(fname, "a") as myfile:
myfile.write(res)
myfile.close()
# with open('nodes.txt','w') as nfile:
# for n in nodes:
# nfile.write("{} {} {}\n".format(n.x, n.y, n.nodeid))
# with open('basestation.txt', 'w') as bfile:
# bfile.write("{} {} {}\n".format(bsx, bsy, 0))
print ars_data_collision_initial
print ars_data_collision