Sigfox Interview questions and answers

This page covers top Sigfox interview questions and answers will help interviewee pass the job interview for Sigfox technology engineer job position. This Sigfox questions are written by specialists in LPWAN domain.

Question -1: Which frequency band is used in USA and Europe for Sigfox ?
Answer -1: 868 MHz is used in Europe where as 915 MHz is used in USA.

Question -2: What is the distance covered by Sigfox ?
Answer -2: Sigfox supports distance of about 30 to 50 Km in rural areas where as 3 to 10 Km in urban areas.

Question -3: Which modulation schemes are supported by Sigfox ? Explain them.
Answer -3: BPSK and GFSK modulation schemes are used by sigfox in the uplink (From End Points to Gateway) and downlink (From Gateway to End Points) respectively.

Question -4: Draw Sigfox network architecture and explain function of each sigfox network elements.
Answer -4: It uses LTN (Low Throughput Network) architecture. It consists of end objects, sigfox gateway (or Base Station), Sigfox cloud and IT applications running on servers.

Refer Sigfox network architecture >> which describes its network elements and interfaces between these elements.

Question -5: What are the advantages and disadvantages of Sigfox technology ?
Answer -5: Advantages : It handles small messages efficiently and handles low data rate IoT/M2M applications. It offers increased battery life, increased network capacity, wide coverage and lower cost etc.
Disadvantages : CSMA/CA or any other such techniques are not employed in Sigfox. It can not handle high data rate applications. It is not efficient to use in mobile environments due to interference and other issues.

Question -6: Describe frame structure of Sigfox.
Answer -6: Following figure mentions uplink MAC frame and downlink MAC frame used by Sigfox technology.

Uplink MAC Frame = { Preamble (4 bytes), Frame synchronization (2 bytes) , End Point ID (4 bytes), Payload (0 to 12 bytes) , Authentication (var. length) , FCS (2 bytes, used as CRC) }
Downlink MAC Frame = { Preamble (32 bits or 4 bytes), Frame synchronization (13 bits), Flags (2 bits), FCS (8 bits), Authentication (16 bits), Error codes (variable), Payload (Variable) }

Question -7: Mention different sigfox protocol stack layers and their functions.
Answer -7: Following are the protocol layers in a sigfox stack.
RF Layer : It handles frequency and power assignments of end points and BSs.
PHY Layer : It takes care of preamble addition and removal. It takes care of modulation and demodulation part also.
MAC Layer : It performs MAC frame management, FCS for error detection and so on.
Application Layer : Different applications are supported in this LTN technology.

Question -8: What is the size of message supported by Sigfox technology ?
Answer -8: For 12 bytes of data to be transported sigfox frame uses 26 bytes in total.

Question -9: What is the difference between Sigfox and 5G ?
Answer -9: Following table mentions difference between sigfox and 5G technologies.

Question -10: What is the difference between Sigfox and LoRaWAN ?
Answer -10: Following table mentions difference between LoRaWAN and Sigfox technologies.

This set of Sigfox interview questions and answers are useful for freshers and experienced level of job positions.

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