Due to impediments associated with cable-based seismic survey, Wireless Seismic Data Acquisition (WSDA) has recently gained much attention fromcontractors, exploration companies, and researchers to layout enabling wireless technology and architecture for Wireless Geophone Networks (WGN) in seismic explorations. A potential approach is to employ multi-hop wireless ad-hoc communication. In this study, we propose a multi-hop WGN architecture consisting of several subnetworks to realize the expected network performance. We investigate the performance of proactive and reactive routing protocols to examine the optimal number of geophones that could be effectively supported within a subnetwork. The performance metrics used are packet delivery ratio (PDR) and average end-to-end delay

Ahmed, Musab Eltayeb Ahmed

Kuladinithi, Koojana

Makama, Aliyu

Timm-Giel, Andreas

English

Electronic Communications of the EASST (European Association of Software Science and Technology)

Electronic Communications of the EASSTVolume 080 (2021)Conference on Networked Systems 2021(NetSys 2021)Evaluation of Multi-hop Ad-hoc Routing Protocols in Wireless SeismicData AcquisitionAliyu Makama, Koojana Kuladinithi, Musab Ahmed Eltayeb Ahmed, Andreas Timm-Giel5 pagesGuest Editors: Andreas Blenk, Mathias Fischer, Stefan Fischer, Horst Hellbrueck, OliverHohlfeld, Andreas Kassler, Koojana Kuladinithi, Winfried Lamersdorf, Olaf Landsiedel, AndreasTimm-Giel, Alexey VinelECEASST Home Page: http://www.easst.org/eceasst/ ISSN 1863-2122ECEASSTEvaluation of Multi-hop Ad-hoc Routing Protocols in WirelessSeismic Data AcquisitionAliyu Makama1, Koojana Kuladinithi2, Musab Ahmed Eltayeb Ahmed3, AndreasTimm-Giel41aliyu.makama@tuhh.de, 2koojana.kuladinithi@tuhh.de, 3musab.ahmed@tuhh.de,4timm-giel@tuhh.de, https://www.tuhh.de/et6Institute of Communication NetworksHamburg University of Technology, GermanyAbstract: Due to impediments associated with cable-based seismic survey, Wire-less Seismic Data Acquisition (WSDA) has recently gained much attention fromcontractors, exploration companies, and researchers to layout enabling wireless tech-nology and architecture for Wireless Geophone Networks (WGN) in seismic explo-rations. A potential approach is to employ multi-hop wireless ad-hoc communica-tion. In this study, we propose a multi-hop WGN architecture consisting of severalsubnetworks to realize the expected network performance. We investigate the per-formance of proactive and reactive routing protocols to examine the optimal numberof geophones that could be effectively supported within a subnetwork. The perfor-mance metrics used are packet delivery ratio (PDR) and average end-to-end delay.Keywords: Wireless Geophone Network (WGN), Wireless Gateway (GW), CentralControl Unit (CCU), Wireless Seismic Data Acquisition (WSDA)1 IntroductionSeismic survey is a method of obtaining an image of the earth’s sub-surface structure in orderto determine optimal places to drill for oil and gas. In land survey, an energy source generatesvariable frequency waves (referred to as sweep or shot) that propagates down the earth’s sur-face. These waves are reflected and refracted as they hit various subsurface layers, which arerecorded by devices at the surface called geophones and then sent down to the Central ControlUnit (CCU) for further processing. The source is then moved to the next shot point and theprocess is repeated. Depending on the coverage area, the survey can last for several weeks. Ameasured geophone response sampled at 0.5 ms and digitized with 24 bit resolution will resultin a data rate of 48 kbit/s. WGNs are often large-scale networks with tens of thousands of geo-phones deployed along receiver lines, covering several squares of kilometres of the survey area.For real-time WSDA systems, defining a scalable network architecture and employing a suitablewireless technology is of essential importance. Infrastructure based architectures for WGNs havebeen proposed in many literatures, [RSA+19] etc., whereby group of geophones transmit theirsensed data to a wireless gateway (GW), and from the gateway down to the CCU in single-hop.However, this increases the number of GWs to be deployed in the survey. Higher data rate, highercommunication coverage, and regard for imposed cost are some of the key factors to considerwhen selecting wireless technology for WGNs.1 / 5 Volume 080 (2021)Evaluation of Multi-hop Ad-hoc Routing Protocols in Wireless Seismic Data AcquisitionNetwork Architecture: Our proposal is to enable multi-hop ad-hoc communication in theWGN architecture proposed in [MKT21], to reduce the number of GWs to be deployed, whilekeeping the WGNs performance intact. Therefore, a flat-based network architecture in whichthe survey area is divided into subnetworks is employed (Figure 1). Each subnetwork consists ofcertain number of geophones that relay their seismic data via neighbouring geophones to a GWnode over multi-hop wireless network. The GW then forwards the aggregated data to the CCU.The size of the subnetwork determines the optimal number of hops supported satisfying theWGN requirements, with 100% PDR and the upper limit of the delay for real-time acquisitionsystems. To limit the effect of adjacent and co-channel interference, neighbouring GWs areexpected to use non-overlapping channels in such a way that no adjacent subnetwork uses thesame channel.Traffic Demand in a Subnetwork: The common orthogonal geometry where receiver andsource lines are placed perpendicular to each other is employed [CGP00]. Geophones are placedon four parallel receiver lines, separated by a distance of 200 m and an inter-geophone distanceof 25 m as defined in a typical survey [RSA+19]. The traffic from each geophone is gener-ated according to the geophone recording period acquisition technique in [MKT21], at a rate of48 kbit/s which is transmitted to the GW node. Depending on the number of hops, a forwardinggeophone will transmit twice the rate or more, as shown in Figure 1 (logical view). Althoughthe data generated per geophone is quite small, the aggregate data generated in a subnetworkcould be significantly large. If the subnetwork size has been selected with up to 200 nodes max-imum, around 9.6 Mbit/s of the network capacity will be required with per node data rate of48 kbit/s, assuming all nodes can reach the GW in a single hop. However, this value increaseswith more number of hops in the network. Moreover, when various protocol headers are takeninto consideration the available bit rate is less than the nominal data rate.Wireless Technologies: Considering the large-scale geophone deployment and higher datarate requirements, wireless communication technologies/protocols used in conventional WirelessSensor Networks (WSN) such as, IEEE 802.15.4 or LoRa are not suitable for WGNs. Longerrange random access technologies like IEEE 802.11af and IEEE 802.11ah are more suitable asthey can cover more geophones and can provide higher data rates.The main goal of this work is to evaluate a suitable routing protocol to enable multi-hop ad-hoc communication in a WGN subnetwork with acceptable network performance. Ad-hoc inthis work refers to infrastructure-less communication. Many routing protocols for wireless ad-hoc networks have been discussed and classified based on the underlying network structure (i.e.flat, tree, mesh, and hierarchical based) in literature [PNV13].The ad-hoc routing protocols are categorized as pro-active, reactive, and hybrid [PNV13].In proactive protocols route to destinations are established and maintained by periodically dis-tributing routing information in the network. In reactive protocols, route discovery is initiatedonly on demand from source nodes. Two prominent proactive protocols i.e., Optimised LinkState Routing “OLSR” (mostly used in mobile ad-hoc networks) and IPv6 Routing Protocol forLow-Power and Lossy Networks “RPL” (commonly used in WSNs), and a widely used reactiveprotocol i.e., Ad-hoc On-demand Distance Vector “AODV” are investigated in this study. IEEE802.11g, which has same random access behavior of CSMA/CA like in IEEE 802.11af, IEEE802.11ad, is used as an example MAC protocol to evaluate the multi-hop routing protocols.OLSR is based on link-state algorithm, that uses the concept of multipoint relays (MPR) toNetSys 2021 2 / 5ECEASST200 m25 mCentral Control UnitGatewayGeophoneChannel A Channel B Channel CSource LineSubnetwork Subnetwork SubnetworkReceiver LineShot pointsWGN with multiple subnetworks (Physical view) multi-hop connectivity in a subnetwork(Logical view)Figure 1: Architecture for Wireless Geophone Networksoptimize the number of control messages flooded in the network. RPL is an IPv6 distance vectorprotocol that employs the concept of Destination Oriented Directed Acyclic Graph (DODAG) toestablish network topology, with all links oriented towards the sink or DODAG root. It uses anobjective function to construct routes, which define how routing metrics and other constraints aretaken into account when building the network topology[WTB+12]. AODV is a distance vectorprotocol based on the bellman-ford algorithm in which route discovery is initiated on demandby a transmitting node. Using OMNeT++ simulation tool, we evaluate the performance of theseprotocols considering WGN’s traffic pattern, network size and structure to analyze the size of asubnetwork.2 Results AnalysisOne subnetwork with various network size settings is configured in OMNeT++ simulator asshown in Figure 1. Each geophone accumulates the data during the interval of 250 ms andsend the accumulated data periodically till the end of geophone recording period of 5 s, for asingle shot. The payload size of a single packet is configured as 1500 B (= 48 kbit/s at 250 ms).IEEE802.11g is used with ad-hoc mode of operation supporting both 11 Mbit/s and 54 Mbit/sdata rates. The latter is used to investigate the routing protocol performance for the maximumachievable data rate in 802.11g, as 11 Mbit/s might not be enough to cater for our applicationdata rates over several hops.Figure 2 shows WGN requirement of the PDR of 100% can be achieved only up to 20 nodesirrespective of the type of routing protocol used to enable multi-hop communication in a subnetwork, when using 11 Mbit/s. The offered load approaches the maximum capacity the networkcan handle, thereby leading to severe packet loss at the MAC layer due to retransmission failuresor queue overflow. In addition to the offered load, routing overhead resulting from periodicexchange of hello message and topology control messages further occupies the network capacity.In general, higher number of routing overhead is involved in proactive compared to reactiverouting. Here, AODV shows a slight improvement in PDR beyond 20 nodes with 11 Mbit/s.Some cases, RPL shows better PDR, compared to OLSR as it uses the trickle timer algorithm todynamically adjust the rate of sending control packets.3 / 5 Volume 080 (2021)Evaluation of Multi-hop Ad-hoc Routing Protocols in Wireless Seismic Data AcquisitionFigure 2: Packet delivery ratio Figure 3: Average end-to-end delayThe PDR of RPL and OLSR outperform AODV when using 54 Mbit/s. The PDR for allprotocols closely follows till the network size (N) of 80 where the network capacity can bearthe offered load and the routing overhead with mulit-hop communication. At N = 100, thePDR for AODV protocol significantly drops to almost 50%. This is caused by the specific trafficmodel of the WGN. Geophones transmit data packets almost simultaneously during the geophonerecording period of 5 s. This is a bottleneck for AODV as route discovery process is initiatedwhenever a node wants to transmit a packet, thereby overloading the network capacity withroute request (RREQ) packets leading to collisions. This results in failure in route discoveryprocess causing more packets to be dropped.Figure 3 shows the average packet end-to-end delay in the network. As expected, the delaydecreases with higher data rate as a lower data rate implies longer packet transmission time. Thedelay increases with increase in network size as a packet might travel over two or three hops.In addition, as the probability of collision increases with an increase in network size, packetswill take longer time in the queue due to the CSMA/CA back-off algorithm, especially in AODVprotocol during the route establishment process.3 ConclusionThe preliminary study sets to investigate the performance of proactive and reactive protocols inWGNs, with focus on determining the optimal number of geophones that could be supported in asubnetwork. The initial results show that this clearly depends on the type of link layer technology(data rate, MAC) and the underlying routing protocols strategy. RPL and OLSR show morepromising results as compared to AODV protocol. These protocols offer low delay during theroute setup process as routes are immediately available when data transmission begins. However,high bandwidth requirement might be a major drawback in OLSR as the control overhead isproportional to the number of nodes in the network. RPL looks more promising in terms of costeffectiveness as it employs trickle mechanism to optimize the dissemination of topology controlinformation over the network. Future work will be directed towards realizing the architecturepresented in Figure 1 with enhancements to MAC scheme, e.g., dedicating the resources, andalso to optimizing the routing strategy within the subnetworks.NetSys 2021 4 / 5ECEASSTAcknowledgements: This work is supported by Deutscher Akademischer Austauschdienst(DAAD) under the Nigerian-German Postgraduate Training Programme, in collaboration withthe Nigerian Petroleum Technology Development Fund (PTDF).Bibliography[CGP00] A. Cordsen, M. Galbraith, J. Peirce. Planning Land 3-D Seismic Surveys. Society ofExploration Geophysicists, Jan. 2000.[MKT21] A. Makama, K. Kuladinithi, A. Timm-Giel. Wireless Geophone Networks for LandSeismic Data Acquisition: A Survey, Tutorial and Performance Evaluation. Sensors21(15), 2021.doi:10.3390/s21155171[PNV13] N. A. Pantazis, S. A. Nikolidakis, D. D. Vergados. Energy-Efficient Routing Proto-cols in Wireless Sensor Networks: A Survey. IEEE Communications Surveys Tuto-rials 15(2):551–591, 2013.doi:10.1109/SURV.2012.062612.00084[RSA+19] V. A. Reddy, G. L. Stuber, S. Al-Dharrab, W. Mesbah, A. H. Muqaibel. A WirelessGeophone Network Architecture using IEEE 802.11af with Power Saving Schemes.IEEE Transactions on Wireless Communications, pp. 5967–5982, 2019.doi:10.1109/TWC.2019.2940944[WTB+12] T. Winter, P. Thubert, A. Brandt, J. Hui, R. Kelsey, P. Levis, K. Pister, R. Struik,JP. Vasseur, R. Alexander. RPL: IPv6 Routing Protocol for Low-Power and LossyNetworks. Technical report RFC6550, RFC Editor, Mar. 2012.5 / 5 Volume 080 (2021)

Evaluation of Multi-hop Ad-hoc Routing Protocols in Wireless Seismic Data Acquisition

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Evaluation of Multi-hop Ad-hoc Routing Protocols in Wireless Seismic Data Acquisition

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