Weightless-P is an ultra high performance LPWAN connectivity technology for the Internet of Things. It will use a narrow band modulation scheme offering a bidirectional communications capability to enable unrivalled quality of service (QoS) and add on functionality. The Standard will provide fully acknowledged 2-way communications offering both uplink and downlink capabilities and best in class QoS required for the stringent industrial IoT sector.
Weightless-P will offer the promised performance, network reliability and security characteristics of 3GPP carrier grade solutions but significantly earlier than these technologies are likely to come on line. In addition the Standard will enable substantially lower costs, comparable to other LPWAN technologies, and less than 100uW power consumption in idle state compared to more than 3mW for the best cellular technologies.
Excellent capacity & scalability for IoT deployment
When IoT connectivity technologies are being considered, adopters rightly consider parameters like cost, battery life and range but it’s easy to overlook the importance of network capacity. And in the absence of empirical data from real world network deployments, we can be tempted to rely too heavily on theory rather than properly modelled scenarios which take into account the many factors impacting capacity in the real world. Capacity is not just about the number of simultaneously connected nodes, it is about mean data packet length, transmission time, frequency of transmissions and interference mitigation. Scaleability is also strongly impacted by the choices made in radio parameters from ultra narrowband at one end of the spectrum to wide band at the other. Not surprisingly, both give rise to upsides and downsides and the capacity sweet spot is a compromise between the two. Narrowband channels offer the optimal capacity for uplink dominated traffic from a large number of devices with moderate payload sizes and typical transmission duty cycles so Weightless-P uses 12.5kHz channels. Weightless-P also offers flexible channel assignment which further enhances network capacity by enabling frequency reuse in large scale deployments while adaptive data rates from 200bps to 100kbps permit optimal radio resource usage to maximise capacity. Time synchronised base stations allow for radio resource scheduling and utilisation. Weightless-P operates across the entire range of licence exempt sub-GHz ISM/SRD bands for global deployment.
Fully acknowledged transmissions
LPWAN technologies fall into three categories - uplink only, uplink and partial downlink capability and 100% fully acknowledged transmissions. Weightless-P supports full acknowledgement of all transmissions where required. Some alternative LPWAN technologies offer downlink capabilities limited to a very small proportion of transmissions meaning that reliability and QoS is compromised. Weightless-P also supports acknowledged and unacknowledged unicast and multicast traffic. It offers a flexible acknowledgement scheme including deferred and combined acknowledgement for improved resource usage. It also supports both network originated and device originated traffic with paging capacity and low latency in both uplink and downlink. It enables fast network acquisition, Forward Error Correction (FEC), Automatic Retransmission Request (ARQ), Adaptive Channel Coding (ACC), handover, roaming and cell re-selection. Real bidirectional capability also supports over-the-air firmware upgrade and security key negotiation or replacement.
Long range in urban environment
Range is frequently cited as one of the key parameters of an IoT system, especially in challenging conditions such as dense urban environments and in locations where the antenna position is compromised such as inside a building. LPWAN technologies are commonly promoted with varying claims with respect to range but the reality is that all technologies operating in sub-GHz unlicensed spectrum are subject to the same conditions, regulations and laws of physics. Range is ultimately determined by signal path, link budget, antenna size, quality, position and location, data rate and transmission power. Lower data rates with channel coding provide for a similar link budget to alternative LPWAN technologies and so achieve a typical range of 2km in an urban environment. In reality it is only possible to offer a typical range - a more accurate claim would require actual modelling in the specific environment. Weightless-P is specified with a realistic range in a dense urban environment which is closer to that achievable from all licence exempt LPWAN technologies.
Industrial grade reliability
Choosing a LPWAN technology has traditionally involved a compromise - high performance, high cost and high power consumption from cellular based technologies operating in licensed spectrum, or more modest performance from a low cost, low power technology in licence exempt bands. Today the decision will typically be driven by the use case; where cost and power consumption are not critical and where Quality of Service and reliability are priorities then the larger amounts of licensed spectrum with less restriction on transmit power suggests 3GPP technologies. But Weightless-P represents a game changer with its ‘clean slate’ design philosophy. By leveraging proven concepts from cellular technologies with a robust and tailored MAC and PHY, Weightless-P brings carrier grade performance at a low cost, low complexity price point. Indeed, Weightless-P supports licensed spectrum operation meeting mandatory selectivity/blocking performance requirements ensuring good coexistence in licensed bands without any protocol changes. Across all spectrums, including sub-GHz bands, Weightless-P offers industrial grade reliability.
Ultra-low energy consumption
Many IoT applications terminals will be powered by batteries leading to the need for low energy consumption. All LPWAN technologies operating in licence exempt spectrum are low power but Weightless-P uses a number of techniques to offer best in class power consumption performance and consequently very long battery life. Overall energy consumption is a factor of both the power used during transmission and the amount of the time that the transmitter is active - the duty cycle. Weightless-P uses GMSK and offset-QPSK modulation schemes which deliver optimum power amplifier efficiency. Offset-QPSK modulation is also inherently interference immune and using spread spectrum for improved link quality in busy radio environments minimises the required transmit power. The low transmit power of 17dBm means that terminals can operate from coin cell batteries. Adaptive data rate also permits minimal transmit power for nodes with a cleaner signal path to the base station so maximising battery life. And since a terminal device will nearly always spend a very large proportion of the time in an idle state, the power consumption in this mode becomes critical. Weightless-P consumes less than 100µW when inactive.
Unbeatable secure networking
Security is a critical factor in virtually all IoT use cases so systems based on Weightless-P technology benefit from leading edge data security provision. AES-128/256 encryption and authentication of both the terminal and the network guarantees integrity whilst temporary device identifiers offer anonymity for maximum security and privacy. OTA security key negotiation or replacement is possible whilst a future-proof cipher negotiation scheme with a minimum key length of 128 bits protects long term investment in the network integrity.
Low cost & complexity
In most IoT use cases commercial feasibility, and therefore cost, is one of the most important criteria for adopters. It is one of the key factors in the decision to use LPWAN technologies in licence exempt spectrum rather than the considerably more complex and higher cost cellular M2M or forthcoming NB-IOT alternative. This decision usually involves a technical compromise but Weightless-P actually offers near 3GPP grade performance - without a cost penalty. Intelligent clean slate design borrowing from proven cellular techniques and a no-compromise innovative philosophy delivers premium LPWAN technology at a low end price point. Quasi-symmetrical two-way communication with all of the intrinsic advantages this offers is core to Weightless-P technology but delivered for the same cost as simple unidirectional alternatives. Standard GMSK and offset-QPSK modulation means broad availability of hardware without dependency on a single vendor, consistent with the open standard Weightless ethos, and a maximal 17dBm transmit power enables the use of an integrated power amplifier minimising BoM cost of terminals.
Low cost & complexity
In most IoT use cases commercial feasibility, and therefore cost, is one of the most important criteria for adopters. It is one of the key factors in the decision to use LPWAN technologies in licence exempt spectrum rather than the considerably more complex and higher cost cellular M2M or forthcoming NB-IOT alternative. This decision usually involves a technical compromise but Weightless-P actually offers near 3GPP grade performance - without a cost penalty. Intelligent clean slate design borrowing from proven cellular techniques and a no-compromise innovative philosophy delivers premium LPWAN technology at a low end price point. Quasi-symmetrical two-way communication with all of the intrinsic advantages this offers is core to Weightless-P technology but delivered for the same cost as simple unidirectional alternatives. Standard GMSK and offset-QPSK modulation means broad availability of hardware without dependency on a single vendor, consistent with the open standard Weightless ethos, and a maximal 17dBm transmit power enables the use of an integrated power amplifier minimising BoM cost of terminals.
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