Energy-Efficient and Reliable IoT Access without Radio Resource Reservation
ABSTARCT :
One of the major challenges for Internet-of-Things applications is that the existing cellular technologies do not support the uplink IoT traffic in an energy-efficient manner. There are two principal ways for serving the uplink IoT traffic: grant-based (i.e., scheduled) and grant-free (i.e., random access). Grant-based access provides fine-grained control of reliability and latency at the cost of energy consumption required for signaling. Grant-free access removes the signaling overhead at the cost of looser control of performance in terms of reliability and latency. However, a precise analysis of reliability, latency and energy performance of grant-free access (GFA) is largely missing. This article focuses on a GFA-type protocol, in which a device transmits several packet replicas, asynchronously with respect to the other devices. Using stochastic geometry, we derive closed-form expressions for reliability, delay, and energy consumption, which can be used to identify the tradeoffs among these performance parameters. In order to improve the performance of the protocol, we develop a receiver that leverages the random timing and frequency offsets among the devices in order to facilitate resolution of collisions. This is complemented by a per-device adaptive scheme that controls the number of transmitted replicas. The evaluation confirms the validity of the analysis and the potential of the proposed solution, identifying operating regions in which GFA outperforms the grant-based access.
EXISTING SYSTEM :
? The ultimate goal of IoT is to enhance existing services and applications or deliver new ones to users, with little to no human intervention.
? Cellular LPWANs extend the existing cellular systems, allowing the reuse of the same architecture for long-range IoT scenarios and applications, and in particular mMTC.
? It is built upon GSM networks and existing cellular base stations with a simple software update.
? Any new device that has performed an INQUIRY procedure to enter the existing scatternet is absorbed in the scatternet.
DISADVANTAGE :
• Capacity of wireless channels shared by many users with finite block-lengths and without scheduling, was partially investigated in; however, it is still an open problem, especially when it comes to time-frequency overlapping packet transmissions.
? In the context of the 3GPP standardization, the set of radio resources that should be allocated to GFA communications, the choice of modulation and coding scheme, and the impact on grantbased communications were investigated in.
? The reliability and scalability analysis of GFA are also active study items in the 3GPP standardization; the main focus is on assessing the impact of the number of devices that share radio resources dedicated to grant-free communications on reliability.
PROPOSED SYSTEM :
• This paper presents an extensive literature survey on the methodologies and approaches used and proposed to increase the energy efficiency and thus lower the power consumption of the most widespread IoT technologies.
• Moreover, the paper also provides a deep analysis of proposed energy and power consumption models for the same technologies, and attempts to create a classification of said methods.
• The proposed model was tested by introducing the PSM in the NS3-based NB-IoT simulator provided in, which is an adaptation of the LTE physical layer to NB-IoT.
• A NB-IoT power consumption model was also proposed in, aiming at estimating device battery lifetime.
ADVANTAGE :
? We develop an analytical approach to assess the reliability, delay and energy efficiency performance of GFA in such scenarios, assuming that devices are able to send multiple replicas of their data packets.
? In, performance of a massive grant-free network was investigated and approximate expressions for outage probability and throughput were derived.
? In, an advanced compressed sensing technique for massive GFA connectivity was proposed, and its performance in reliable detection of simultaneously active devices investigated.
? In order to optimize the performance of such hybrid access solutions in future networks, the load regions where one access mode outperforms the other should be known.
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