Proposal and evaluation of BLE discovery process based on new features of bluetooth 5.0

The device discovery process is one of the most crucial aspects in real deployments of sensor networks. Recently, several works have analyzed the topic of Bluetooth Low Energy (BLE) device discovery through analytical or simulation models limited to version 4.x. Non-connectable and non-scannable undirected advertising has been shown to be a reliable alternative for discovering a high number of devices in a relatively short time period. However, new features of Bluetooth 5.0 allow us to define a variant on the device discovery process, based on BLE scannable undirected advertising events, which results in higher discovering capacities and also lower power consumption. In order to characterize this new device discovery process, we experimentally model the real device behavior of BLE scannable undirected advertising events. Non-detection packet probability, discovery probability, and discovery latency for a varying number of devices and parameters are compared by simulations and experimental measurements. We demonstrate that our proposal outperforms previous works, diminishing the discovery time and increasing the potential user device density. A mathematical model is also developed in order to easily obtain a measure of the potential capacity in high density scenarios.Peer ReviewedPostprint (published version

Proposal and evaluation of BLE discovery process based on new features of bluetooth 5.0

The device discovery process is one of the most crucial aspects in real deployments of sensor networks. Recently, several works have analyzed the topic of Bluetooth Low Energy (BLE) device discovery through analytical or simulation models limited to version 4.x. Non-connectable and non-scannable undirected advertising has been shown to be a reliable alternative for discovering a high number of devices in a relatively short time period. However, new features of Bluetooth 5.0 allow us to define a variant on the device discovery process, based on BLE scannable undirected advertising events, which results in higher discovering capacities and also lower power consumption. In order to characterize this new device discovery process, we experimentally model the real device behavior of BLE scannable undirected advertising events. Non-detection packet probability, discovery probability, and discovery latency for a varying number of devices and parameters are compared by simulations and experimental measurements. We demonstrate that our proposal outperforms previous works, diminishing the discovery time and increasing the potential user device density. A mathematical model is also developed in order to easily obtain a measure of the potential capacity in high density scenarios

Contributions to bluetooth low energy mesh networks

Bluetooth Low Energy (BLE) has become a popular Internet of Things (IoT) technology. However, it was originally designed to only support the star topology. This PhD thesis investigates and evaluates different Bluetooth Low Energy (BLE) mesh network approaches, including existing ones (such as the Bluetooth Mesh standard), and our own solution for IPv6-based BLE mesh networking (6BLEMesh). The thesis comprises 6 main contributions: 1.- A comprehensive survey on existing BLE mesh networking proposals and a taxonomy for BLE mesh network solutions. 2.- An energy consumption model for Bluetooth Mesh. The model allows to predict useful performance parameters, such as device average current consumption, device lifetime and energy efficiency, considering the impact of the most relevant Bluetooth Mesh parameters, i.e. PollTimeout and ReceiveWindow, as well as application parameters (e.g. the data interval for a sensor that periodically reports its readings). 3.- A new proposed IPv6-based BLE mesh networking IETF standard (in progress), called 6BLEMesh. After defining the characteristics and properties of 6BLEMesh, we evaluated it in terms of connectivity, latency, RTT, and energy consumption. 4.- For the connectivity evaluation of 6BLEMesh, we developed an analytical model that takes a set of network and scenario characteristics as inputs, and provides two main results: i) the probability of no isolation of a node, and ii) the k-connectivity of the considered network. We validated the model by simulation. 5.- An implementation, and an experimental evaluation, of 6BLEMesh. We built a three-node testbed consisting of all node types (i.e. 6LN, 6LR and 6LBR). We used three different popular commercial hardware platforms. We evaluated a number of performance parameters on the testbed, related with latency and energy consumption. Next, we characterized the current consumption patterns of the complete life cycle for different node types in the three-node testbed. We also evaluated the energy performance of a 6LN on three different platforms. We presented a 6LN current consumption model for different connInterval settings. To this end, we experimentally characterized each current consumption state in terms of its duration time and average current consumption value. We illustrated the impact of connInterval on energy performance. 6.- A comparison between Bluetooth Mesh and 6BLEMesh, in terms of protocol stack, protocol encapsulation overhead, end-toend latency, energy consumption, message transmission count, end-to-end reliability, variable topology robustness and Internet connectivity. Bluetooth Mesh and 6BLEMesh offer fundamentally different BLE mesh networking solutions. Their performance depends significantly on their parameter configuration. Nevertheless, the following conclusions can be obtained. Bluetooth Mesh exhibits slightly greater protocol encapsulation overhead than 6BLEmesh. Both Bluetooth Mesh and 6BLEMesh offer flexibility to configure per-hop latency. For a given latency target, 6BLEMesh offers lower energy consumption. In terms of message transmission count, both solutions may offer relatively similar performance for small networks; however, BLEMesh scales better with network size and density. 6BLEMesh approaches ideal packet delivery probability in the presence of bit errors for most parameter settings (at the expense of latency increase), whereas Bluetooth Mesh requires path diversity to achieve similar performance. Bluetooth Mesh does not suffer the connectivity gaps experimented by 6BLEMesh due to topology changes. Finally, 6BLEMesh naturally supports IP-based Internet connectivity, whereas Bluetooth Mesh requires a protocol translation gateway.Bluetooth Low Energy (BLE) ha esdevingut una tecnologia popular per a Internet of Things (loT). Ara bé, va ser originalment dissenyada per suportar només la topologia en estrella. Aquesta tesi doctoral investiga i avalua diferents alternatives de xarxa mesh BLE, incloent alternatives existents (com l'estandard Bluetooth Mesh), i la nostra propia solució basada en IPv6, 6BLEMesh. Aquesta tesi comprén 6 contribucions·principals: 1.- Una revisió exhaustiva de l'estat de l'art i una taxonomia de les xarxes mesh BLE. 2.- Un model de consum d'energia per Bluetooth Mesh. El model permet predir parametres de rendiment útils, tals com consum de corrent, temps de vida del dispositiu i eficiéncia energética, considerant !'impacte deis principals parametres de Bluetooth Mesh (PollTimeout i ReceiveWindow) i a nivell d'aplicació. 3.- Un nou estandard (en progrés) anomenat 6BLEMesh. Després de definir les característiques de 6BLEMesh, aquesta solució ha estat avaluada en termes de connectivitat, laténcia, RTT i consum d'energia. 4.- Per a l'avaluació de connectivitat de 6BLEMesh, hem desenvolupat un model analític que proporciona dos resultats principals: i) probabilitat de no arllament d'un node i ii) k-connectivitat de la xarxa considerada. Hem validat el model mitjani;:ant simulació. .- Una imP.lementació, i una avaluació experimental, de 6BLEMesh. S'ha construrt un testbed de tres nodes, que comprén 5tots els tipus de node principals (6LN, 6LR i 6LBR). S'han usat tres plataformes hardware diferents. S'han avaluat diversos parametres de rendiment en el testbed, relacionats amb laténcia i consum d'energia. A continuació, s'ha caracteritzat els patrons de consum de corren! d'un ciclde de vida complet per als diferents tipus de nodes en el testbed. També s'han avaluat les prestacions d'energia d'un 6LN en tres plataformes diferents. S'ha presenta! un model de consum de corren! d'un 6LN per a diferents valors de connlnterval. Per aquest fi, s'ha caracteritzat emplricament cada estat de consum de corrent en termes de la seva durada i consum de corrent. 6.- Una comparativa entre Bluetooth Mesh i 6BLEMesh, en termes de pila de protocols, overhead d'encapsulament de protocol, laténcia extrem a extrem, consum d'energia, nombre de missatges transmesos, fiabilitat extrem a extrem, robustesa davant de topologies variables, i connexió a Internet. Bluetooth Mesh i 6BLEMesh són solucions de BLE mesh networking fonamentalment diferents. Les seves prestacions depenen de la seva configuració de parametres. Ara bé, es poden extreure les següents conclusions. Bluetooth Mesh mostra un overhead d'encapsulament de protocol lleugerament superior al de 6BLEmesh. Tots dos, Bluetooth Mesh i 6BLEMesh, ofereixen flexibilitat per configurar la laténcia per cada salt. Per un target de laténcia doni¡it, 6BLEMesh ofereix un consum d'energia inferior. En termes de nombre de missatges transmesos, les dues solucions ofereixen prestacions relativament similars per a xarxes petites. Ara bé, 6BLEMesh escala millor amb la mida i la densitat de la xarxa. 6BLEMesh s'aproxima a una probabilitat d'entrega de paquets ideal en preséncia d'errors de bit (amb un increment en la laténcia), mentre que Bluetooth Mesh requereix diversitat de caml per assolir unes prestacions similars. Bluetooth Mesh no pateix els gaps de connectivitat que experimenta 6BLLEMesh a causa de canvis en la topología. Finalment, 6BLEMesh suporta de forma natural la connectivitat amb Internet basada en IP, mentre que Bluetooth Mesh requereix un gateway de traducció de protocols.Postprint (published version

Contributions to bluetooth low energy mesh networks

Bluetooth Low Energy (BLE) has become a popular Internet of Things (IoT) technology. However, it was originally designed to only support the star topology. This PhD thesis investigates and evaluates different Bluetooth Low Energy (BLE) mesh network approaches, including existing ones (such as the Bluetooth Mesh standard), and our own solution for IPv6-based BLE mesh networking (6BLEMesh). The thesis comprises 6 main contributions: 1.- A comprehensive survey on existing BLE mesh networking proposals and a taxonomy for BLE mesh network solutions. 2.- An energy consumption model for Bluetooth Mesh. The model allows to predict useful performance parameters, such as device average current consumption, device lifetime and energy efficiency, considering the impact of the most relevant Bluetooth Mesh parameters, i.e. PollTimeout and ReceiveWindow, as well as application parameters (e.g. the data interval for a sensor that periodically reports its readings). 3.- A new proposed IPv6-based BLE mesh networking IETF standard (in progress), called 6BLEMesh. After defining the characteristics and properties of 6BLEMesh, we evaluated it in terms of connectivity, latency, RTT, and energy consumption. 4.- For the connectivity evaluation of 6BLEMesh, we developed an analytical model that takes a set of network and scenario characteristics as inputs, and provides two main results: i) the probability of no isolation of a node, and ii) the k-connectivity of the considered network. We validated the model by simulation. 5.- An implementation, and an experimental evaluation, of 6BLEMesh. We built a three-node testbed consisting of all node types (i.e. 6LN, 6LR and 6LBR). We used three different popular commercial hardware platforms. We evaluated a number of performance parameters on the testbed, related with latency and energy consumption. Next, we characterized the current consumption patterns of the complete life cycle for different node types in the three-node testbed. We also evaluated the energy performance of a 6LN on three different platforms. We presented a 6LN current consumption model for different connInterval settings. To this end, we experimentally characterized each current consumption state in terms of its duration time and average current consumption value. We illustrated the impact of connInterval on energy performance. 6.- A comparison between Bluetooth Mesh and 6BLEMesh, in terms of protocol stack, protocol encapsulation overhead, end-toend latency, energy consumption, message transmission count, end-to-end reliability, variable topology robustness and Internet connectivity. Bluetooth Mesh and 6BLEMesh offer fundamentally different BLE mesh networking solutions. Their performance depends significantly on their parameter configuration. Nevertheless, the following conclusions can be obtained. Bluetooth Mesh exhibits slightly greater protocol encapsulation overhead than 6BLEmesh. Both Bluetooth Mesh and 6BLEMesh offer flexibility to configure per-hop latency. For a given latency target, 6BLEMesh offers lower energy consumption. In terms of message transmission count, both solutions may offer relatively similar performance for small networks; however, BLEMesh scales better with network size and density. 6BLEMesh approaches ideal packet delivery probability in the presence of bit errors for most parameter settings (at the expense of latency increase), whereas Bluetooth Mesh requires path diversity to achieve similar performance. Bluetooth Mesh does not suffer the connectivity gaps experimented by 6BLEMesh due to topology changes. Finally, 6BLEMesh naturally supports IP-based Internet connectivity, whereas Bluetooth Mesh requires a protocol translation gateway.Bluetooth Low Energy (BLE) ha esdevingut una tecnologia popular per a Internet of Things (loT). Ara bé, va ser originalment dissenyada per suportar només la topologia en estrella. Aquesta tesi doctoral investiga i avalua diferents alternatives de xarxa mesh BLE, incloent alternatives existents (com l'estandard Bluetooth Mesh), i la nostra propia solució basada en IPv6, 6BLEMesh. Aquesta tesi comprén 6 contribucions·principals: 1.- Una revisió exhaustiva de l'estat de l'art i una taxonomia de les xarxes mesh BLE. 2.- Un model de consum d'energia per Bluetooth Mesh. El model permet predir parametres de rendiment útils, tals com consum de corrent, temps de vida del dispositiu i eficiéncia energética, considerant !'impacte deis principals parametres de Bluetooth Mesh (PollTimeout i ReceiveWindow) i a nivell d'aplicació. 3.- Un nou estandard (en progrés) anomenat 6BLEMesh. Després de definir les característiques de 6BLEMesh, aquesta solució ha estat avaluada en termes de connectivitat, laténcia, RTT i consum d'energia. 4.- Per a l'avaluació de connectivitat de 6BLEMesh, hem desenvolupat un model analític que proporciona dos resultats principals: i) probabilitat de no arllament d'un node i ii) k-connectivitat de la xarxa considerada. Hem validat el model mitjani;:ant simulació. .- Una imP.lementació, i una avaluació experimental, de 6BLEMesh. S'ha construrt un testbed de tres nodes, que comprén 5tots els tipus de node principals (6LN, 6LR i 6LBR). S'han usat tres plataformes hardware diferents. S'han avaluat diversos parametres de rendiment en el testbed, relacionats amb laténcia i consum d'energia. A continuació, s'ha caracteritzat els patrons de consum de corren! d'un ciclde de vida complet per als diferents tipus de nodes en el testbed. També s'han avaluat les prestacions d'energia d'un 6LN en tres plataformes diferents. S'ha presenta! un model de consum de corren! d'un 6LN per a diferents valors de connlnterval. Per aquest fi, s'ha caracteritzat emplricament cada estat de consum de corrent en termes de la seva durada i consum de corrent. 6.- Una comparativa entre Bluetooth Mesh i 6BLEMesh, en termes de pila de protocols, overhead d'encapsulament de protocol, laténcia extrem a extrem, consum d'energia, nombre de missatges transmesos, fiabilitat extrem a extrem, robustesa davant de topologies variables, i connexió a Internet. Bluetooth Mesh i 6BLEMesh són solucions de BLE mesh networking fonamentalment diferents. Les seves prestacions depenen de la seva configuració de parametres. Ara bé, es poden extreure les següents conclusions. Bluetooth Mesh mostra un overhead d'encapsulament de protocol lleugerament superior al de 6BLEmesh. Tots dos, Bluetooth Mesh i 6BLEMesh, ofereixen flexibilitat per configurar la laténcia per cada salt. Per un target de laténcia doni¡it, 6BLEMesh ofereix un consum d'energia inferior. En termes de nombre de missatges transmesos, les dues solucions ofereixen prestacions relativament similars per a xarxes petites. Ara bé, 6BLEMesh escala millor amb la mida i la densitat de la xarxa. 6BLEMesh s'aproxima a una probabilitat d'entrega de paquets ideal en preséncia d'errors de bit (amb un increment en la laténcia), mentre que Bluetooth Mesh requereix diversitat de caml per assolir unes prestacions similars. Bluetooth Mesh no pateix els gaps de connectivitat que experimenta 6BLLEMesh a causa de canvis en la topología. Finalment, 6BLEMesh suporta de forma natural la connectivitat amb Internet basada en IP, mentre que Bluetooth Mesh requereix un gateway de traducció de protocols

Anti-Collision Adaptations of BLE Active Scanning for Dense IoT Tracking Applications

Bluetooth low energy (BLE) is one of most promising technologies to enable the Internet-of-Things (IoT) paradigm. The BLE neighbor discovery process (NDP) based on active scanning may be the core of multiple IoT applications in which a large and varying number of users/devices/tags must be detected in a short period of time. Minimizing the discovery latency and maximizing the number of devices that can be discovered in a limited time are challenging issues due to collisions between frames sent by advertisers and scanners. The mechanism for resolution of collisions between scanners has a great impact on the achieved performance, but backoff in NDP has been poorly studied so far. This paper includes a detailed analysis of backoff in NDP, identifies and studies the factors involved in the process, reveals the limitations and problems presented by the algorithm suggested by the specifications and proposes simple and practical adaptations on scanner functionality. They are easily compatible with the current definitions of the standard, which together with a new proposal for the backoff scheme, may significantly improve the discovery latencies and, thus, the probability of discovering a large number of devices in high density scenarios

PSM-DMO: power save mode and discontinuous BLE mesh operation

The Bluetooth Low Energy (BLE) mesh profile, standardized by the Bluetooth Special Interest Group (SIG), has an increasing interest in IoT solutions. However, the standard assumes that relay and friend nodes should be continuously scanning the channel awaiting any incoming transmissions. This could be very inefficient in terms of energy consumption, particularly in application scenarios where the backbone of the mesh network cannot be powered and traffic is infrequent. Hence, we present a novel strategy, named PSM-DMO, that minimizes the scan periods and thus, significantly reduces the overall energy consumption of the mesh network. PSM-DMO is defined as a new and optional feature for the currently published BLE mesh specifications, coexists with the standard operation, and is implemented without modifying the core of the specification. The proposal, that ensures the reliability of the mesh operation, can be used in BLE sensor networks that can tolerate a certain transmission delay. PSM-DMO replaces the continuous scan by a periodic but asynchronous polling process whereby the relay and sink nodes interrogate their neighbors about the existence of data to receive or to retransmit through the network. Nodes only go into scan mode during the period of time the mesh network will be involved in the transmission and dissemination. This period is estimated by the node which is the source of data, it is announced to its neighbors and it is propagated consecutively by all the relay nodes until the destination. PSM-DMO allows a theoretical reduction in the energy consumption of relay nodes up to 99.24 %.This work has been supported in part by the Spanish Ministry of Science through the projects RTI2018-099880-B-C32. RTI2018-095684-B-I00 and RTI2018-099063-B-I00 with ERFD funds, and by the Government of Aragon (Reference Group T31_20R).Peer ReviewedPostprint (published version

PSM-DMO: power save mode and discontinuous BLE mesh operation

The Bluetooth Low Energy (BLE) mesh profile, standardized by the Bluetooth Special Interest Group (SIG), has an increasing interest in IoT solutions. However, the standard assumes that relay and friend nodes should be continuously scanning the channel awaiting any incoming transmissions. This could be very inefficient in terms of energy consumption, particularly in application scenarios where the backbone of the mesh network cannot be powered and traffic is infrequent. Hence, we present a novel strategy, named PSM-DMO, that minimizes the scan periods and thus, significantly reduces the overall energy consumption of the mesh network. PSM-DMO is defined as a new and optional feature for the currently published BLE mesh specifications, coexists with the standard operation, and is implemented without modifying the core of the specification. The proposal, that ensures the reliability of the mesh operation, can be used in BLE sensor networks that can tolerate a certain transmission delay. PSM-DMO replaces the continuous scan by a periodic but asynchronous polling process whereby the relay and sink nodes interrogate their neighbors about the existence of data to receive or to retransmit through the network. Nodes only go into scan mode during the period of time the mesh network will be involved in the transmission and dissemination. This period is estimated by the node which is the source of data, it is announced to its neighbors and it is propagated consecutively by all the relay nodes until the destination. PSM-DMO allows a theoretical reduction in the energy consumption of relay nodes up to 99.24 %

A low-cost tracking system for running race applications based on bluetooth low energy technology

Timing points used in running races and other competition events are generally based on radio-frequency identification (RFID) technology. Athletes’ times are calculated via passive RFID tags and reader kits. Specifically, the reader infrastructure needed is complex and requires the deployment of a mat or ramps which hide the receiver antennae under them. Moreover, with the employed tags, it is not possible to transmit additional and dynamic information such as pulse or oximetry monitoring, alarms, etc. In this paper we present a system based on two low complex schemes allowed in Bluetooth Low Energy (BLE): the non-connectable undirected advertisement process and a modified version of scannable undirected advertisement process using the new capabilities present in Bluetooth 5. After fully describing the system architecture, which allows full real-time position monitoring of the runners using mobile phones on the organizer side and BLE sensors on the participants’ side, we derive the mobility patterns of runners and capacity requirements, which are determinant for evaluating the performance of the proposed system. They have been obtained from the analysis of the real data measured in the last Barcelona Marathon. By means of simulations, we demonstrate that, even under disadvantageous conditions (50% error ratio), both schemes perform reliably and are able to detect the 100% of the participants in all the cases. The cell coverage of the system needs to be adjusted when non-connectable process is considered. Nevertheless, through simulation and experimental, we show that the proposed scheme based on the new events available in Bluetooth 5 is clearly the best implementation alternative for all the cases, no matter the coverage area and the runner speed. The proposal widely exceeds the detection requirements of the real scenario, surpassing the measured peaks of 20 sensors per second incoming in the coverage area, moving at speeds that range from 1.5 m/s to 6.25 m/s. The designed real test-bed shows that the scheme is able to detect 72 sensors below 600 ms, fulfilling comfortably the requirements determined for the intended application. The main disadvantage of this system would be that the sensors are active, but we have proved that its consumption can be so low (9.5 µA) that, with a typical button cell, the sensor battery life would be over 10,000 h of use.Peer ReviewedPostprint (published version

A low-cost tracking system for running race applications based on bluetooth low energy technology

Timing points used in running races and other competition events are generally based on radio-frequency identification (RFID) technology. Athletes’ times are calculated via passive RFID tags and reader kits. Specifically, the reader infrastructure needed is complex and requires the deployment of a mat or ramps which hide the receiver antennae under them. Moreover, with the employed tags, it is not possible to transmit additional and dynamic information such as pulse or oximetry monitoring, alarms, etc. In this paper we present a system based on two low complex schemes allowed in Bluetooth Low Energy (BLE): the non-connectable undirected advertisement process and a modified version of scannable undirected advertisement process using the new capabilities present in Bluetooth 5. After fully describing the system architecture, which allows full real-time position monitoring of the runners using mobile phones on the organizer side and BLE sensors on the participants’ side, we derive the mobility patterns of runners and capacity requirements, which are determinant for evaluating the performance of the proposed system. They have been obtained from the analysis of the real data measured in the last Barcelona Marathon. By means of simulations, we demonstrate that, even under disadvantageous conditions (50% error ratio), both schemes perform reliably and are able to detect the 100% of the participants in all the cases. The cell coverage of the system needs to be adjusted when non-connectable process is considered. Nevertheless, through simulation and experimental, we show that the proposed scheme based on the new events available in Bluetooth 5 is clearly the best implementation alternative for all the cases, no matter the coverage area and the runner speed. The proposal widely exceeds the detection requirements of the real scenario, surpassing the measured peaks of 20 sensors per second incoming in the coverage area, moving at speeds that range from 1.5 m/s to 6.25 m/s. The designed real test-bed shows that the scheme is able to detect 72 sensors below 600 ms, fulfilling comfortably the requirements determined for the intended application. The main disadvantage of this system would be that the sensors are active, but we have proved that its consumption can be so low (9.5 µA) that, with a typical button cell, the sensor battery life would be over 10, 000 h of use

Bluetooth low energy mesh networks: a survey

luetooth Low Energy (BLE) has gained significant momentum. However, the original design of BLE focused on star topology networking, which limits network coverage range and precludes end-to-end path diversity. In contrast, other competing technologies overcome such constraints by supporting the mesh network topology. For these reasons, academia, industry, and standards development organizations have been designing solutions to enable BLE mesh networks. Nevertheless, the literature lacks a consolidated view on this emerging area. This paper comprehensively surveys state of the art BLE mesh networking. We first provide a taxonomy of BLE mesh network solutions. We then review the solutions, describing the variety of approaches that leverage existing BLE functionality to enable BLE mesh networks. We identify crucial aspects of BLE mesh network solutions and discuss their advantages and drawbacks. Finally, we highlight currently open issuesPeer ReviewedPostprint (published version