Exercises

Question:1 5G is now entering worldwide deployment with China in the lead and Europe/US in pursuit and India also gearing up for early deployments. The current focus is on smart phones in public networks, but private networks, IoT and uRLLC leveraged applications are still not mainstage. Follow on the Brunei approach to 5G deployment?

Question:2 An unlicensed spectrum band with mmWave frequencies ranging from 116 GHz to 123 GHz that has been proposed for use in the next generation of wireless communication systems. If a total of 7 GHz of bandwidth is allocated to a particular FDD cellular telephone system which uses two 25 kHz simplex channels to provide full duplex channels, compute the number of channels available per cell if a system uses 7-cell reuse .

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Question3: The spectrum band, with frequencies ranging from 250 to 350 GHz, was proposed as the basis for the first worldwide wireless communications standard. Suppose a particular FDD cellular telephone system with a total of 100 Gbps of data rate and channel bandwidths ranging from 2 GHz to 70 GHz is assigned a total of two 25 kHz simplex channels to provide full duplex voice and control channels. If the system employs 12-cell reuse, compute the number of channels available per cell. Determine an equitable distribution of control channels and voice channels in each cell for the system if 1 MHz of the allocated spectrum is dedicated to control channels.

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Question:4 Let $f_c = 142 GHz$, $h_t=40m$, $h_r =5 m$, and $d=10 km$. where $f_c$ = carrier frequency, $h_t$ = height of transmitting antenna (base station), $h_r$ = height of receiving antenna (mobile unit),$d$ = propagation distance between antennas. Estimate the path loss for medium-size city (See figure).

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Question:5 A cellular service provider decides to use a digital TDMA scheme which can tolerate a signal-to-interference ratio of $15$ dB in the worst case. Find the optimal value of N for (a) omni-directional antennas, (b) $120^{0}$ sectoring, and Ic) $60^{0}$ sectoring. Should sectoring be used? If so, which case $(60^{0} or 120^{0})$ should be used? (Assume a path loss exponent of $n = 4$ and consider trunking efficiency).If an intensive propagation measurement campaign showed that the mobile radio channel provided a propagation path loss exponent of $n = 3$ instead of $4$, how would your design decisions in Problem change? What is the optimal value of $N$ for the case of $n = 3$?

Answer: $N=4$

Question:6 A receiver in an urban cellular radio system detects a $1$ mW signal at $d = 1$ meter from the transmitter. In order to mitigate co-channel interference effects, it is required that the signal received at any base station receiver from another base station transmitter which operates with the same channel must be below -$100$ dBm. A measurement team has determined that the average path loss exponent in the system is $n = 3$. Determine the major radius of each cell if a $7$-cell reuse pattern is used. What is the major radius if a $4$-cell reuse pattern is used?

Answer: $r > 470.1$m

Question:7 The cellular system using a cluster size of 7 is described in Problem $6$. It is operated with 660 channels, 30 of which are designated as setup (control) channels so that there are about 90 voice channels available per cell. If there is a potential user density of 9000 $users/km^2$ in the system, and each user makes an average of one call per hour and each call lasts $1$ minute during peak hours, determine the number of users in a cell.

Answer: $5167$ users

Question8: Provide drawings to show interference with (a)cluster size $3$, $60^{0}$sectoring with $6$ sectors, (b) cluster size $3$,$120^{0}$sectoring with 3 sectors.

Answer: