adriancooney/2014_2015_CH140_1_1_5.json

## 2014_2015_CH140_1_1_5.json
{
    "section_a": {
        "1": {
            "i": {
                "content": " Explain using examples why many hard RTS use a cyclic executive   approach to scheduling whereas many soft RTS utilise a real-time    operating system.           [10]  "
            },
            "ii": {
                "content": " Using Antilock Braking Systems (ABS) as an example, distinguish   between the sample rate and response time of a RTS.             [10]  "
            },
            "iii": {
                "content": " Quality of Experience (QoE) is a related though much broader concept   than Quality of Service (QoS). Distinguish between the two terms     using MMOG (Massively Multiplayer Online Gaming) as an example.                       [10]  "
            },
            "iv": {
                "content": "Distinguish between narrowband (NB), wideband (WB), and super-  wideband (SWB) voice codec\u2019s, outlining the        advantages/disadvantages of each.          [10]                    \f 3 "
            }
        },
        "3": {
            "i": {
                "content": " As a senior network designer for an IP communications provider, you are    asked to outline a complete end-to-end  infrastructural design for a potential   Irish client company that wishes to implement an all-IP based conferencing   (voice/video) system. The company will have two large facilities, in Dublin   and Galway, each with their own LAN. Your design should address the    following issues: \u2022 How to choose VoIP phones to maximise voice quality \u2022 How QoS will be achieved across company LANs \u2022 How QoS will be achieved across WAN. You can assume that your company uses DiffServ in its IP network.           [25]  "
            },
            "ii": {
                "content": "MPEG-DASH and WebRTC are two recent developments in    multimedia. Explain briefly what they are, how they work, and the    extent to which time and or timing are important.           [15] \f 5  "
            }
        },
        "2": {
            "i": {
                "content": " Distinguish briefly between time and timing synchronisation, using   Voice-over-IP (VoIP) as an example.            [10]  "
            },
            "ii": {
                "content": " Using each of the following examples, explain firstly - whether time,   timing, or both types of synchronisation are important and secondly -   outline the level of synchronisation required:  \u2022 Electrical Power Phasor Measurement Units (PMU) \u2022 Fault diagnosis in a Distributed Control System  \u2022 MMOG (Massively Multiplayer Online Gaming) Server servicing players from across the globe                       [15]          "
            },
            "iii": {
                "content": "The data below shows the output of the ntpq utility from 2 NTP clients, A   and B.    Based on the output, which client is most likely to deliver better    Synchronisation? Your answer should comment on redundancy, offsets, delay,   stratum level and reachability.  ClientA  RefID   st  t When  Poll Reach Delay  Offset Jitter +server1 serverx 2 u 51 64 156 391.281 6.24 7.79 -server 2 servery 2 u 49 64 372 353.217 10.435 1.663 *server3 serverz 2 u 50 64 356 85.688 2.465 2.666 +server4 .PPS. 1 u 49 64 357 66.369 1.858 2.105 Client B   RefID   st  t When  Poll Reach Delay  Offset Jitter +server5 serverm 2 u 45 64 377 36.345 2.24 3.458 -server 6 servern 2 u 42 64 377 313.217 3.435 1.11 *server7 .PPS. 1 u 13 64 377 10.688 1.485 1.455 +server8 .PPS. 1 u 22 64 377 28.456 1.818 1.345 +server9 .GPS. 1 u 18 64 356 15.345 -2.654 2.34                       [15]      \f 4 "
            }
        }
    },
    "section_b": {
        "5": {
            "i": {
                "content": "Briefly discuss the concept of N-modular hardware redundancy. Furthermore, provide an example for a redundant system that consists of  - N=3 independent components that have a failure probability of 10% each and  - a 2v3 voter. Calculate the overall system reliability.           [8]  "
            },
            "ii": {
                "content": "Using examples show how",
                "a": {
                    "content": "a 2-disks RAID-0,"
                },
                "c": {
                    "content": "a 4-disks RAID-5 system respond to the failure of an entire hard disk.           [10] "
                },
                "b": {
                    "content": "a 2-disks RAID-1, and"
                }
            },
            "iii": {
                "content": "The diagram below illustrates the Worst Case Execution Time (WCET) for a sample task under both offline code analysis (dark shaded) and actual runtime testing (light shaded). Explain each of the indicated points and ranges in the diagram and outline the importance of such analysis in RTS design.             [10]          Section continues on next page. \f 7  "
            },
            "iv": {
                "content": "Using the task set in Table 2 below: - Calculate the overall CPU utilisation U.  - Determine the process schedule using the RM scheduling algorithm. - Determine the process schedule using the EDF scheduling algorithm.  - Comment on the difference between both schedules.  Task Execution Time Period 1 10 50 2 20 100 3 20 150 4 80 200  Table 2                              [12]  "
            }
        },
        "4": {
            "i": {
                "a": {
                    "content": "deeply embedded systems (ES),"
                },
                "c": {
                    "content": "medium ES,"
                },
                "b": {
                    "content": "shallow ES,"
                },
                "e": {
                    "content": "critical ES. Provide examples for any 4 of these categories that can be found in a car.           [6] "
                },
                "d": {
                    "content": "commodity ES and"
                },
                "content": "Briefly distinguish between"
            },
            "ii": {
                "content": "Using the source code snippet below show in detail how a stack overflow can be caused and how it compromises the run-time stack of a process.             [10]  "
            },
            "iii": {
                "content": "How can the Hamming (7, 4) code be used to encode 8-bit data? What error correcting and error detecting capabilities does the resulting encoding scheme have?           [12] "
            },
            "iv": {
                "content": "Consider you are a member of a development team responsible for the control software of a washing machine. The software is controlled by a scheduler based on the cyclic executive approach. It controls 3 tasks with cycle times of 50 msec, 75 msec and 100 msec as shown in Table 1 below. The execution time of each task is well below its cycle time.  Task Period (msec) Exec Time (msec) A 50 10 B 75 10 C 100 10  Table 1   Section continues on next page. \f 6  Using (pseudo and/or C) code, prototype a timer-interrupt-controlled cyclic executive for the above task schedule. Your answer must include an implementation of the timer-interrupt service routine. Also, task A overruns occasionally (e.g. its execution time is about 60 msec). Enhance your cyclic executive to detect such violations.                     [12]  "
            }
        },
        "6": {
            "i": {
                "content": "Memory locking is an important feature of POSIX 4. Use the code snippet below and the 7-state process model to explain why this feature is important for (hard) real-time systems.             [10] "
            },
            "ii": {
                "content": "What is meant by the priority inversion problem and how can it be solved? Use an example to illustrate your answer.            [12]          Section continues on next page. \f 8   "
            },
            "iii": {
                "content": "Summarise the main features of POSIX signals. Furthermore, outline the purpose and functionality of the structure sigaction below and show how this structure allows the handling of queued signals as defined in POSIX.4.             [10] "
            },
            "iv": {
                "content": "Discuss how static software redundancy can be provided via N-version programming. What are the advantages and what are potential pitfalls of this approach? Furthermore, briefly elaborate on different voter types that can be used.           [8]  \f"
            }
        }
    }
}
	{
	"section_a": {
	"1": {
	"i": {
	"content": " Explain using examples why many hard RTS use a cyclic executive approach to scheduling whereas many soft RTS utilise a real-time operating system. [10] "
	},
	"ii": {
	"content": " Using Antilock Braking Systems (ABS) as an example, distinguish between the sample rate and response time of a RTS. [10] "
	},
	"iii": {
	"content": " Quality of Experience (QoE) is a related though much broader concept than Quality of Service (QoS). Distinguish between the two terms using MMOG (Massively Multiplayer Online Gaming) as an example. [10] "
	},
	"iv": {
	"content": "Distinguish between narrowband (NB), wideband (WB), and super- wideband (SWB) voice codec\u2019s, outlining the advantages/disadvantages of each. [10] \f 3 "
	}
	},
	"3": {
	"i": {
	"content": " As a senior network designer for an IP communications provider, you are asked to outline a complete end-to-end infrastructural design for a potential Irish client company that wishes to implement an all-IP based conferencing (voice/video) system. The company will have two large facilities, in Dublin and Galway, each with their own LAN. Your design should address the following issues: \u2022 How to choose VoIP phones to maximise voice quality \u2022 How QoS will be achieved across company LANs \u2022 How QoS will be achieved across WAN. You can assume that your company uses DiffServ in its IP network. [25] "
	},
	"ii": {
	"content": "MPEG-DASH and WebRTC are two recent developments in multimedia. Explain briefly what they are, how they work, and the extent to which time and or timing are important. [15] \f 5 "
	}
	},
	"2": {
	"i": {
	"content": " Distinguish briefly between time and timing synchronisation, using Voice-over-IP (VoIP) as an example. [10] "
	},
	"ii": {
	"content": " Using each of the following examples, explain firstly - whether time, timing, or both types of synchronisation are important and secondly - outline the level of synchronisation required: \u2022 Electrical Power Phasor Measurement Units (PMU) \u2022 Fault diagnosis in a Distributed Control System \u2022 MMOG (Massively Multiplayer Online Gaming) Server servicing players from across the globe [15] "
	},
	"iii": {
	"content": "The data below shows the output of the ntpq utility from 2 NTP clients, A and B. Based on the output, which client is most likely to deliver better Synchronisation? Your answer should comment on redundancy, offsets, delay, stratum level and reachability. ClientA RefID st t When Poll Reach Delay Offset Jitter +server1 serverx 2 u 51 64 156 391.281 6.24 7.79 -server 2 servery 2 u 49 64 372 353.217 10.435 1.663 server3 serverz 2 u 50 64 356 85.688 2.465 2.666 +server4 .PPS. 1 u 49 64 357 66.369 1.858 2.105 Client B RefID st t When Poll Reach Delay Offset Jitter +server5 serverm 2 u 45 64 377 36.345 2.24 3.458 -server 6 servern 2 u 42 64 377 313.217 3.435 1.11 server7 .PPS. 1 u 13 64 377 10.688 1.485 1.455 +server8 .PPS. 1 u 22 64 377 28.456 1.818 1.345 +server9 .GPS. 1 u 18 64 356 15.345 -2.654 2.34 [15] \f 4 "
	}
	}
	},
	"section_b": {
	"5": {
	"i": {
	"content": "Briefly discuss the concept of N-modular hardware redundancy. Furthermore, provide an example for a redundant system that consists of - N=3 independent components that have a failure probability of 10% each and - a 2v3 voter. Calculate the overall system reliability. [8] "
	},
	"ii": {
	"content": "Using examples show how",
	"a": {
	"content": "a 2-disks RAID-0,"
	},
	"c": {
	"content": "a 4-disks RAID-5 system respond to the failure of an entire hard disk. [10] "
	},
	"b": {
	"content": "a 2-disks RAID-1, and"
	}
	},
	"iii": {
	"content": "The diagram below illustrates the Worst Case Execution Time (WCET) for a sample task under both offline code analysis (dark shaded) and actual runtime testing (light shaded). Explain each of the indicated points and ranges in the diagram and outline the importance of such analysis in RTS design. [10] Section continues on next page. \f 7 "
	},
	"iv": {
	"content": "Using the task set in Table 2 below: - Calculate the overall CPU utilisation U. - Determine the process schedule using the RM scheduling algorithm. - Determine the process schedule using the EDF scheduling algorithm. - Comment on the difference between both schedules. Task Execution Time Period 1 10 50 2 20 100 3 20 150 4 80 200 Table 2 [12] "
	}
	},
	"4": {
	"i": {
	"a": {
	"content": "deeply embedded systems (ES),"
	},
	"c": {
	"content": "medium ES,"
	},
	"b": {
	"content": "shallow ES,"
	},
	"e": {
	"content": "critical ES. Provide examples for any 4 of these categories that can be found in a car. [6] "
	},
	"d": {
	"content": "commodity ES and"
	},
	"content": "Briefly distinguish between"
	},
	"ii": {
	"content": "Using the source code snippet below show in detail how a stack overflow can be caused and how it compromises the run-time stack of a process. [10] "
	},
	"iii": {
	"content": "How can the Hamming (7, 4) code be used to encode 8-bit data? What error correcting and error detecting capabilities does the resulting encoding scheme have? [12] "
	},
	"iv": {
	"content": "Consider you are a member of a development team responsible for the control software of a washing machine. The software is controlled by a scheduler based on the cyclic executive approach. It controls 3 tasks with cycle times of 50 msec, 75 msec and 100 msec as shown in Table 1 below. The execution time of each task is well below its cycle time. Task Period (msec) Exec Time (msec) A 50 10 B 75 10 C 100 10 Table 1 Section continues on next page. \f 6 Using (pseudo and/or C) code, prototype a timer-interrupt-controlled cyclic executive for the above task schedule. Your answer must include an implementation of the timer-interrupt service routine. Also, task A overruns occasionally (e.g. its execution time is about 60 msec). Enhance your cyclic executive to detect such violations. [12] "
	}
	},
	"6": {
	"i": {
	"content": "Memory locking is an important feature of POSIX 4. Use the code snippet below and the 7-state process model to explain why this feature is important for (hard) real-time systems. [10] "
	},
	"ii": {
	"content": "What is meant by the priority inversion problem and how can it be solved? Use an example to illustrate your answer. [12] Section continues on next page. \f 8 "
	},
	"iii": {
	"content": "Summarise the main features of POSIX signals. Furthermore, outline the purpose and functionality of the structure sigaction below and show how this structure allows the handling of queued signals as defined in POSIX.4. [10] "
	},
	"iv": {
	"content": "Discuss how static software redundancy can be provided via N-version programming. What are the advantages and what are potential pitfalls of this approach? Furthermore, briefly elaborate on different voter types that can be used. [8] \f"
	}
	}
	}
	}