7/27/2019 Cluster Intro
1/19
vMonitor Confidential
Cluster Design
What is Cluster?Cluster is group of networked devices
RTU are networked with Gateways
These networks are formed with the help ofSpread Spectrum radio system
7/27/2019 Cluster Intro
2/19
vMonitor Confidential
Spread Spectrum Radio
SPREAD
SPECTRUM RADIO
7/27/2019 Cluster Intro
3/19
vMonitor Confidential
Spread Spectrum Technology
Definition:Spread Spectrum technology is a type of RF
modulation that uses signals that are
intentionally made to be much wider band
than the information they are carrying in order
to make them more noise-like.
Principal features:
Hard to detect or demodulate
Can be distributed over a wide range offrequencies
Comes in two principal type of modulation:
Direct sequence and Frequency Hopping
Hard to exploit or spoof
Direct sequence SS Signal Photo
Frequency Hopping SS Signal Photo
7/27/2019 Cluster Intro
4/19
vMonitor Confidential
Frequency Hopping vs.Direct Sequence Spread
Spectrum - 2
Frequency Hopping (FHSS)
Breaks incoming data into smaller individual packets andtransmits them on separate frequencies
If a packet is not sent successfully on a given frequency, itis re-sent on a another frequency
By re-sending data that was corrupted, the methodbecomes inherently reliable
Receiver recompiles packets into original form
No matter how strong the interferer is the FHSS systemwill continue to communicate
7/27/2019 Cluster Intro
5/19
7/27/2019 Cluster Intro
6/19
vMonitor Confidential
Frequency Hopping vs. DirectSequence Spread Spectrum - 3
There are 79 frequency hops before any frequency is repeatedSpace between each frequency is 1 MHz covering a 79 MHZ band
7/27/2019 Cluster Intro
7/19vMonitor Confidential
SS VS NARROWBAND
7/27/2019 Cluster Intro
8/19
7/27/2019 Cluster Intro
9/19vMonitor Confidential
FREE SPACE LOSS
Free Space Loss:
-L = C + 20*log(D) + 20*log(F)
Where
L = Loss in free space
C = Calculation constant (36.6 if D is Miles or 32.5 if D is in Km)
D = Distance
F = Frequency in MHz.
7/27/2019 Cluster Intro
10/19vMonitor Confidential
Distance Loss at F=
in miles in km 900 MHz 2.4GHz 5.8GHz
1.6 mi 2.5 km 99 dB 108 dB 116 dB
3.1 mi 5 km 106 dB 114 dB 122 dB
5 mi 8 km 110 dB 118 dB 126 dB
6.2 mi 10 km 112 dB 120 dB 128 dB
10 mi 16 km 116 dB 124 dB 132 dB
Free Space Loss: -L = C + 20*log(D) + 20*log(F) Where L = Loss in free space C = Calculation constant (36.6 if D is Miles or 32.5 if D is in Km) D = Distance F = Frequency in MHz.
Typical Free Space Losses at
7/27/2019 Cluster Intro
11/19vMonitor Confidential
Cluster Design for vMonitor RTUs
Cluster design
7/27/2019 Cluster Intro
12/19vMonitor Confidential
Major Aspects of Clusterdesign
Number of wells in field
Geographic Spread of the field
Density of wells per sq. Km
Type of wells and data transfer requirements
Terrain and Locations
Telecom Infrastructure such as Height of tower, WILANBase station antennae. Etc.
Power Requirements
7/27/2019 Cluster Intro
13/19vMonitor Confidential
Design Consideration forCommunication Clusters
Short-hop radios EIRP < 100mW to make it licensed-free.Limit the cluster radius between 1 to 3 Kms.
Theoretically one Gateway can talk to 255 nodes. Ourpresent design is limited to only 50 nodes in a cluster. Allow10 more nodes for future additions.
This helps faster turn around time. Total round-tripresponse time of remote RTU to SCADA queries need to beless than 300 mS.
1 poll for MSV, 2 Polls for WIW/GLW wells, 5 to 6 polls for
ESP wellsIf all GLW/WIW/MSV wells in cluster, poll rate will be as lowas 1 RTU per min.
If all ESP wells in a cluster, poll rate will be 1 RTU per 2min.
7/27/2019 Cluster Intro
14/19vMonitor Confidential
Design Consideration forCommunication Clusters
Line of Sight is key issue in 2.4 GHz frequency band radios.Flat Areas will have better RF signal propogation. Uneventerrain makes RF propagation difficult.
Need higher length communication poles.
Gateway Site need to be higher location and higher pole.
Gateway locations away from any plants, pipe yards ormetal objects.
Line of sight to the nearest Telecoms Tower in the area
Type of Sector or Omnidirectional Antenne for WILAN radios
Path Loss Analysis from Wellhead to Gateway Site
Path Loss Analysis from Gateway Site to Telecoms Tower
7/27/2019 Cluster Intro
15/19
7/27/2019 Cluster Intro
16/19vMonitor Confidential
Cluster design for Fahud
Total 11 Communication ClustersEach cluster limited to 50-60 wellhead RTUs
2 adjacent communication clusters for Pilot Project
New RTU communication pole are 6 m in height
Gateway communication pole are 10 m in height
Small Yagi Antenna for Wellhead RTUs point to gateway site
At gateway we have 2 antennae, one Omni-directionalantenna to communicate with wellhead RTUs, another semi-
parabolic grid antenna for communication to Telecom Tower
7/27/2019 Cluster Intro
17/19vMonitor Confidential
Fahud Clusters & Gateways
7/27/2019 Cluster Intro
18/19
vMonitor Confidential
Fahud Cluster# 3
7/27/2019 Cluster Intro
19/19
vMonitor Confidential
Fahud Cluster# 5