I consider two hosts: Host1 is sending UDP packets (between 1000 and 1500 Bytes) to Host2 and at the same time Host2 is sending UDP packets (also between 1000 and 1500 Bytes) to Host1. The transmission is using different links: There is one Access Point and two Routers involved: Host1 is sending its packets using Wi-Fi (IEEE 802.11g) to the AP. Then the packets are sent over Ethernet (100 Mbit/s) to Router1. The link between Router1 and Router2 is an LTE link. And finally the connection from Router2 to Host2 is Ethernet again. I hope this scenario is more or less clear. Here is my question:

Say we have some other Hosts which are sending 200B requests (HTTP) to a server, using the same link between the AP and Router1. And the server replies to each of these requests with 400kB. How would the UDP packet loss rate of Host1 and also of Host2 depend on the number of Hosts involved in this traffic?

I have run a simulation for this scenario, and as it turns out, the UDP packet loss rate from Host1 to Host2 is actually really big (around 50%). It decreases (!) though with increasing number of hosts engaged in the Client-Server traffic. This is clearly not what I expected. I'm thinking: TCP is well known to acquire bandwidth aggressively. I am not too familiar with details (maybe anyone can help out?) but as far as I remember, TCP does not distribute bandwidth equally among all members participating in traffic. Could this be the reason? Is the bandwdith acquisition maybe more even with increasing number of Hosts?

Interestingly, the UDP packet loss from Host2 to Host1 does not decrease, but increases with rising number of Hosts (Clients). This packet loss rate is very low though anyways. When I increase the datarate of the LTE link (from 8Mbps to 50Mbps), the UDP packet loss rate (in both directions) increases a little bit. This is also not what I expected. The link can handle more traffic now, right? How can the packet loss rate increase?

Any ideas?

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