Comparing Backscatter Communication and Energy Harvesting in Massive IoT Networks

Abstract : Backscatter communication (BC) and radio-frequency energy harvesting (RF-EH) are two promising technologies for extending the battery lifetime of wireless devices. Although there have been some qualitative comparisons between these two technologies, quantitative comparisons are still lacking, especially for massive IoT networks. In this paper, we address this gap in the research literature, and perform a quantitative comparison between BC and RF-EH in massive IoT networks with multiple primary users and multiple low-power devices acting as secondary users. An essential feature of our model is that it includes the interferences caused by the secondary users to the primary users, and we show that these intereferences significantly impact the system performance of massive IoT networks. For the RF-EH model, the power requirements of digital-to-analog and signal amplification are taken into account. We pose and solve a power minimization problem for BC, and we show analytically when BC is better than RF-EH. The results of the numerical simulations illustrate the significant benefits of using BC in terms of saving power and supporting massive IoT, compared to using RF-EH. The results also show that the backscatter coefficients of the BC devices must be individually tunable, in order to guarantee good performance of BC.

 EXISTING SYSTEM :

 ? In this article, we have introduced the basic principles for BackCom, summarized existing BackCom system and network architectures and discussed several emerging advanced BackCom techniques. ? In theory, the number of interference components received by each Reader can increase as the square of the number of coexisting links instead of linearly with the number in the conventional case. ? Therefore, instead of having some specific PBs or Readers that enables tag-toreader communications, the ambient backscatter system can use existing infrastructure and benefit from signals that are not intended for itself. ? Though information flow in RFID applications is usually unidirectional, message exchange between nodes is common in IoT.

 DISADVANTAGE :

 ? A game-theoretic time allocation problem was proposed to improve the network throughput, and an optimal time allocation ratio of energy harvest and backscatter was obtained. ? The 3GPP InH model consists of a distance and frequency dependent deterministic part and a random part that includes the impact of shadowing. ? They displayed performance improvement of the network results from backscatter-assisted cooperation, compared with the normal active information transmission. ? Accurate radio channel characterization and coverage prediction methodology are required in order to efficiently plan a communication network.

 PROPOSED SYSTEM :

 • A joint-energy detection scheme is proposed in that requires only channel variances rather than specific CSI. • An interesting new method for collision avoidance was proposed in for MAC BackCom that treats bursty backscatter transmissions by Tags as a sparse code and decodes multi-Tag data at the Reader using a compressive-sensing algorithm. • The Tag is able to provide energy to the sensor by RF energy harvesting from a wireless controller, and also backscatter the measured blood sugar level to the wireless controller for diagnosing purpose. • In a smart city, ubiquitous BackCom sensor nodes can be placed in every city corner such as buildings, bridges, trees, street lamps, and parking areas.

 ADVANTAGE :

 ? In particular, we evaluate the coverage outage performance of different low-power and wide area technologies, i.e., long range (LoRa) backscatter, arrow band-Internet of Things (NB-IoT), and Bluetooth low energy (BLE) based BC at different frequencies of operation. ? They displayed performance improvement of the network results from backscatter-assisted cooperation, compared with the normal active information transmission. ? The performance metrics considered for the analysis are the received power at the BD, the received power at the Rx, the time required for harvesting the energy at BD, and the outage ratio. ? The first performance metric considered is the forward link received power at the backscatter device.