EE5576: Wireless Communication Systems:
Homework Assignment 6
Given: March 26, 2021
Due: April 2, 2021 (11:59)
Submission Instructions:
Submit your assignment in electronic format (.pdf) directly on Canvas.
Dr. Elena Bernal Mor
Assistant Teaching Professor
Department of Electrical and Computer Engineering
Northeastern University
e-mail : [email protected]
Two adjacent BSs, BSi and BSj are 4 km apart. An MS is moving from BSi to BSj . The path loss is
given by the Okumura-Hata model for urban areas (small and medium cities). We consider that shadowing
and small-scale fading effects are negligible. Assume unity gain (linear units) for transmitter and receiver
antennas, Gt = Gr = 1. The power transmitted by BSi is Pti = 100W , the height of the BS is hb = 60 m
for both BSs, and the height of the MS is hm = 2 m. To compute the path loss, the carrier frequency for
both BSs can be approximated to f = 0.9 GHz.
1. First of all, let’s recall the path loss analysis we saw in Module 2. If the MS is at 2 km from BSi, what
is the average power received at the MS from BSi? Show step by step your solution. (20%)
2. Explain what is the ping-pong effect and why it can happen. (30%)
3. To avoid the ping-pong effect, the threshold for handoff is set to E = 1 dB. If the distance where the
MS starts a handoff is 2.07 km from BSi, what is the power transmitted by BSj? Show step by step
your solution. (50%)
TIP: Work with dB units.

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