Ultra-low power
Extended operation on battery power or the use of energy scavenging is a key requirement in the deployment of wireless device networks. SenzaNET utilizes a precise time synchronization algorithm, allowing all SenzaNET nodes to remain in standby mode when not required to perform a measurement or wireless transaction. In standby mode, nodes can operate on extremely low amounts of current since most hardware components are powered off. As a result, overall power consumption is dramatically reduced and largely correlated with the desired sample rate, rather than unnecessarily drained by idle states.

Bounded communication latency
A secondary benefit of the time synchronization approach is its ability to provide balanced medium access and predictable transmission slots. This keeps latency within tolerable limits, enabling real-time monitoring of assets and guaranteed delivery of time-critical information such as alarms and control commands.  
True mesh networking
The self-organizing and self-healing properties of SenzaNET provide maximum fault tolerance and deployment flexibility. SenzaNET nodes establish connections and transmission paths by themselves, and are capable of multi-hop routing for formation of arbitrary topologies and bridging of extended distances. In contrast to ZigBee, SenzaNET routing nodes do not depend on mains power and can run on batteries. This makes SenzaNET particularly suitable for environments where hardwiring would be difficult or prohibitively expensive. 
Robust and secure transmissions
For maximum reliability, SenzaNET employs automatic retries, acknowledgements, and a channel hopping scheme. Network security is provided through encryption of all data transmissions, and each individual data packet is integrity protected. In addition, join requests by new nodes can be authenticated via access control list so that only known and legitimate nodes are granted access, based on their unique MAC address.  
Field device and fieldbus connectivity
SenzaNET adapters accept 0-20 mA, 4-20 mA, 0-2 V, 0-10 V analog, PT100, pulse, and digital inputs from field devices or meters. Seamless integration with fieldbus and management systems is provided through serial, Ethernet, Profibus, Modbus, CAN, and GPRS gateway interfaces.

Standards Adherence
From the beginning, SenzaNET was designed with standards adherence and customer investment protection in mind. SenzaNET is fully compliant with the IEEE 802.15.4 standard, which is stable and widely accepted in the industry. IEEE 802.15.4 defines the physical and MAC layers of the system, but does not specify topologies. Different topologies require different routing protocols, and even within the same topology class, routing, networking, and transport schemes vary due to the existence of multiple upper layer standards. ZigBee, WirelessHART, ISA100, and 6LoWPAN are examples of existing and future standards that build on IEEE 802.15.4.
As the architectural foundation of E-Senza’s products, the SenzaNET framework is therefore designed to not only conform to its own mesh routing algorithm, but to allow for plug-ins for WirelessHART and 6LoWPAN. This provides customers with choices to appropriately balance technical and time-to-market requirements. The SenzaStack (SN100) version delivers a “WirelessHART lite” solution with lower algorithmical complexity. It therefore requires less memory resources, is easier to analyze and troubleshoot, and provides better performance in areas such as mesh formation time. For those requiring a fully compliant WirelessHART solution, the SNH7 stack and a WirelessHART API are offered. All SenzaNET system components are firmware upgradeable for easy migration to the latest mesh technology, as it becomes commercially available.
E-Senza is an active member of the HART Communication Foundation, and also welcomes and supports the standards efforts of the Internet Engineering Task Force (IETF).

Mesh Networking
Traditionally, wireless networks are based on a star topology in which all nodes communicate directly with the network master, and therefore must be within direct communication range to the master. If end-to-end transmission times are critical, this can be an advantage considering that with every hop a packet traverses, some latency is added. However, star topologies lack both the fault-tolerance required for harsh industrial environments, and the ability to expand the distance of the network in large buildings or outdoor areas. 
For all but the most latency-sensitive applications, mesh topologies are widely viewed as superior. In a mesh topology, data can be forwarded from node to node until the intended final destination is reached. If individual transmission segments are temporarily unavailable, data can be re-routed to an alternate path. This allows the creation of redundant wireless device networks with the ability to self-recover from single points of failure, which considerably increases overall reliability.
Using so-called hybrid topologies - the combination of star and mesh – users can capitalize on the simplicity of the star topology while maintaining the flexibility and resilience of the mesh approach. Peripheral nodes are usually referred to as leaf nodes. SenzaNET supports both leaf and routing node operation, and time synchronization allows all nodes to sleep most of the time to conserve power. As a result, the network layout is not constrained by mains power availability, and no cabling is necessary.

Industrial-Grade Reliability
Unlicensed systems operating on a static frequency channel are often plagued by interference and co-existence problems. SenzaNET is optimized for transmission of relatively small amounts of data, and therefore occupies only a tiny fraction of the available spectrum at any given point in time. Its intelligent, selective use of the spectrum and frequency agility provide maximum robustness and protection against interferers:

• All nodes are tightly time synchronized and transmit in their assigned timeslots only. This Time Division Multiple Access (TDMA) scheme eliminates collisions and provides deterministic latency.
• The IEEE 802.15.4 radio employs a Direct Sequence Spread Spectrum (DSSS) transmission scheme, which spreads the signal over a range of frequencies to assure robustness against signals from narrowband interferers.
• Channel hopping is a proven and effective strategy to withstand interference from the myriads of devices that increasingly crowd the 2.4 GHz band and to mitigate sensitivity to fading in heavy multipath environments. The SenzaNET framework employs a rapid hopping algorithm capable of sustaining the performance and integrity of the wireless network even under extreme conditions.

SenzaNET combines TDMA, DSSS and channel hopping methods with a robust link layer and true mesh networking. Successful reception of transmissions is acknowledged on a per-packet basis, and the protocol will automatically retry delivery if the receiving station doesn‘t acknowledge within the expected period of time. Furthermore, redundant mesh or hybrid topologies effectively protect against failure of individual network components. Field tests have consistently demonstrated that a transmission reliability of greater than 99.9% can be achieved, even in harsh industrial environments.

Fieldbus Integration
Integrating wireless device networks with an existing fieldbus infrastructure can be surprisingly daunting. This is not usually due to deficiencies of either wireless or wired, but rather a reflection of the fact that both were developed completely independently of each other. E-Senza therefore provides complete solutions that not only help customers attain the benefits of wireless, but also ensure that these benefits are not offset by additional efforts required for interworking with their existing systems.
SenzaNET gateways come with connectivity options for the most commonly used fieldbus systems and industrial communication protocols:

• Profibus DP-V1 for cyclic and acyclic data exchanges and alarm handling. The Profibus protocol is in wide use in process automation and primarily used for communication between sensors or actuators and controllers such as PLCs or PCs.
• Modbus-TCP and Modbus-RTU. Modbus-RTU is widely adopted by SCADA systems, usually for communication over a RS485 physical interface. For communication over Ethernet, the more recent variant Modbus-TCP exists.
• The Controller Area Network (CAN) is another serial bus system used for industrial automation and control applications. The CAN protocol is well known for its high transmission reliability and real-time capabilities.

For deployments in remote locations where no infrastructure exists, E-Senza additionally offers a GSM/GPRS option. The extra large 64 MByte gateway buffer ensures that no sensor readings are discarded even in the event of a temporarily lost or weak cellular signal.