## 3 Development of Thermal Condition Monitoring System
### Overview of WSNs and Communication Links Characteristics
#### 3.3.3 Real-Time and Quality of Service Characteristics  
Although wireless communication infrastructure peculiarities impact relative countermeasures of signal propagation challenges, real-time applications are however feasible in its case of implementation. Real-time characteristics of WSNs require the sensor network techniques to provide mechanisms that guarantee certain level of quality of service (QoS). Whereas added objective functioning of the sensor network is to minimizing energy consumption. This presents a paradigm of schemes that delivers WSNs application-level QoS efficiently and charts the mandates to achieve network-layer metrics devoid of jitter and latency. Data delivery delay in WSNs present specific system design challenges and denies signal throughput [64; 67; 72].  
Real-time characteristics of a system prove relevant when even one deadline miss could have serious concerns of the network performance and reliability. Given the importance of having guarantees of deterministic signals, it is desirable to develop a centralized access protocol for real-time signal paradigm reasonably than a random access. The IEEE 802.15.4 and ZigBee deploy hybrid approach of centralized master/slave of Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) and PAN Coordinator (PC). This allocates up to seven (7) Guaranteed Time Slots (GTS), both probabilistic and deterministic real-time signal guarantees. This seeks to achieve a mandate exploiting the advantages of a centralized scheme with access to the channel regulation by a central node which permits the application of scheduling possible deterministic signal through performance during the phase called Contention Free Period (CFP) [74; 75; 76; 71]  
Sigfox and LoRa differ in application characteristics and frequency band unlike ZigBee which operates fully on ISM band. Besides, Sigfox and LoRa have limited access to some countries of application and of different communication protocols. Again, their capabilities are not that resilient to offer the same QoS provided by NB-IoT/LTE. Contrarily, the NB-IoT/LTE deployment is on licensed spectrum and LTE-based synchronous protocols have guarantee of very good QoS with high input and operational cost, which involve licensed LTE spectrum lease cost. Due to the QoS and cost tradeoff, the NB-IoT/LTE favors the applications that involve guaranteed quality of service (QoS) and of very high conscious security, whereas applications that do not have such features should consider LoRa or Sigfox [65; 68; 69; 70]. Additionally, unlike Sigfox, LoRa offers class C features to also handle low-bidirectional latency at the expense of increased energy consumption. Consequently, for applications that are impervious to latency and do not involve large amount of data transmission, Sigfox and class-A of LoRa could be optionally considered. However, for applications that requires low latency and long range of star topology, NB-IoT/LTE and class-C LoRa are the better choices but with cost implications and low data rate [66; 67; 68; 69; 70].