1. a) A 2G mobile network utilises the GSM 900 U radio interface, as illustrated in Fig.1, in its radio access network.

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1 A A 2g Mobile Network Utilises The Gsm 900 U Radio Interface As Illustrated In Fig 1 In Its Radio Access Network 1 (68.32 KiB) Viewed 19 times

1. a) A 2G mobile network utilises the GSM 900 U radio interface, as illustrated in Fig.1, in its radio access network. For both the downlink and uplink spectral regions, two channels located at both edges of each spectral region are not employed to carry any information, and 32 channels are reserved for transmitting organizational data. Based on Fig. 1, answer the following six questions: 900 MH 124 channes (200) 990-915 MI Cech (0) higher GSM frame structures GSM TOMA frame GSM time-slot (normal burst) guard tail user data 67 bits Training S 1 26 bits 1 user data 57 bits 3 bits 540.5 ps 577 μs Fig.1 i) When a single time slot is allocated to each individual mobile user, work out the net signal bit rates for the following three cases: a) a mobile user; b) a frequency channel; and c) the entire cell. [2+2+2-6] ii) Each traffic channel (TCH) has a slow associated dedicated control channel (SACCH) for exchanging network information. When the TCH and SACCH channels share a time slot in a pattern as follows: TTTTTTTTTTTTSTTTTTTTTTTTTX, here T indicates the TCH traffic, S indicates the SACCH traffic and X indicates the unused time slot. Based on the results obtained above, work out the net signal bit rates for TCH and SACCH. [3+2=5] iii) To improve data services provided to end-users, the high-speed circuit switched data (HSCSD) standard was introduced by redefining the use of the ratio interface. Briefly describe the technical approach adopted in the HSCSD standard, and state its key advantages and disadvantages. [2+3=5] iv) Both the multi-path propagation effect and the interference effect between different cells must be reduced. To reduce the multi-path propagation effect, what techniques are adopted in defining the radio interface? and briefly explain the functionalities of each individual technique. On the other hand, to reduce the interference effect between different cells, what frequency planning strategies should be adopted? [2+4+3=9] v) Common control channels (CCCHS) carry all information required for setting up a connection between a MS and the corresponding BTS. To enable the MS to send its call connection request to the BTS, which CCCH channel should the MS use? State the multiple access technique utilised in the adopted channel. [1+1=2] vi) What switching technique is implemented in the GSM network subsystems? How does a MSC handle its signalling information? [1+1=2] frequency guard 4.615 ms