Smartphone Forensics Analysis-Free-Samples for Students-Myassignment

Questions: 1.There is a series of process involved when a switched-on GSM mobile system is getting a channel from its carrier service provider. Please explain the processes. 2.Please explain the investigative values of the identifiers of handset and SIM card. 3.Please explain how the Exponential Back off Algorithm operates. Answers: 1.The channel or the control channel provided by the service provider for a switched on GSM mobile system is of a special frequency that is used to build a link between the mobile system and the base station. There are number of processes associated with this phenomenon. In case the GSM finds it problematic to establish a link with the control channel, it shows an error message. Each carrier frequency associated with the GSM mobile system is segregated in time by making use of the TDMA scheme, the primary unit of which is called burst period. Eight burst periods are generally grouped together, which form the primary units of logical channels. However, one physical channel is a single burst period in one TDMA frame. The position and associated number of the corresponding burst period define the channels obtained from the carrier, and each pattern of burst period is repeated in every two three hours. The control channels are responsible for housekeeping tasks and decide which frequency to use during a call. In order to ensure the handover works, the broadcast control channel upto 16 neighboring cells is monitored by the switched-on GSM. The phone continuously adjusts the radio waves, to receive a clear signal coming from the base station; as the phone is taken far from the base station, the signal strength weakens. In this case, the network consults and enforces a handover to the corresponding neighboring cell or channel, which has considerably good signal (Bechet and Miclaus 2012) 2.Identifiers of handsets: International Mobile Equipment Identity or IMEI number is an unique number associated with every handsets, which is used by an associated GSM network in identifying the identity of valid mobile devices. This number or ID is unique and hence can be used to track a stolen or lost phone. IMEI number tracks the mobile phone by the transmission of the mobile subscriber identity number, which is a unique ID of a SIM card. IMEI number has considerably helped in reducing the number of mobile thefts across the globe (Kumar, Kaur and Gndu 2015). This number is associated with every GSM, WCDMA mobile phones and few satellite phones as well. The other identifiers of handsets are Android ID, UDUD, IDFA, and IDFV. However, IMEI is mostly used as a unique identifier for handsets across the globe. Identifiers of SIM card: An integrated circuit card identifier or ICCID number internationally identifies every SIM. The ICCID number is generally defined by the ITU-T recommendation. The ICCID has different parts, such as IIN or Issuer Identification Number, which is of maximum seven digits, Individual account Identification of variable length and check digit. The format followed in generation of an ICCID number is MMCC IINN NNNN NNNN NN C x. Where, MM is a constant, CC denotes the country code of the SIM, II is the Issuer Identifier N{12} corresponds to account ID or the SIM card number. C is the calculated checksum from other digits by application of Luhn algorithm and finally the x is an extra 20th digit that is obtained as a return of AT!ICCID command. Apart from the ICCID, the SIM also contains an International Mobile Subscriber Identity (IMSI) number (Al-Hadadi and AlShidhani 2013). 3.Exponential Backoff algorithm makes use of feedback to decrease the process rate multiplicatively, with an aim of finding an acceptable rate. This algorithm is used to space out the repeated transmission of same data in order to avoid collision. It has an increasing usage in CSMA/CD as a collision resolution mechanism in random access networks. In case a collision is detected in transmission of a data, the node immediately stops the transmission of data. Exponential Back off algorithm works by sensing the medium when a frame is to be send through the medium. The medium or the channel is continuously monitored for collision and if there is a possibility of a collision, the transmission is aborted with a short jam signal. After a collision, the time frame is segregated into defined slots, with a length same as the worst-case roundtrip propagation time. In order to accommodate the longest path of the Ethernet, the slot time set is 512-bit times. Therefore, after occurrence of first co llision, the channel waits either 0 or 1 time slots at a random before trying again. This set is termed as contention window. In case, the sources collide even after that, the size of the contention window is doubled, which then becomes {0,1,2,3}. The sources of second or subsequent collision then pick an integer randomly from this sets and waits for that time before retransmission to avoid collision. Figure 1: Representing collision avoidance using Exponential Backoff Algorithm (Source: Al?Hubaishi et al. 2014 References Al-Hadadi, M. and AlShidhani, A., 2013. Smartphone forensics analysis: A case study.International Journal of Computer and Electrical Engineering,5(6), p.576. Al?Hubaishi, M., Alahdal, T., Alsaqour, R., Berqia, A., Abdelhaq, M. and Alsaqour, O., 2014. Enhanced binary exponential backoff algorithm for fair channel access in the IEEE 802.11 medium access control protocol.International journal of communication systems,27(12), pp.4166-4184. Bechet, P. and Miclaus, S., 2012. An improved procedure to accurately assess the variability of the exposure to electromagnetic radiation emitted by GSM base station antennas.Measurement Science and Technology,24(1), p.015003. Kumar, K., Kaur, P. and GNDU, A., 2015. Vulnerability detection of international mobile equipment identity number of smartphone and automated reporting of changed IMEI number.International Journal of Computer Science and Mobile Computing,4(5), pp.527-5