What is RTT?

• RTT stands for Round Trip Time. It is the total time taken between sending a request packet to the server and receiving a reply packet from the server.

   What is this map?

• This map shows the "cellular" latency data, i.e. Round Trip Times (RTTs) collected from cellular users across the world using our network measurement server.

    What is the measurement methodology?

• We have setup a measurement server at Madison - Wisconsin, United States to perform the network measurements used to generate this data. The server is used to measure the network latency (Round Trip Times) over UDP from cellular users as shown in the figure.

• This network latency data has been collected by from from thousands of cellular based mobile users from across the world . This data has been used to generate this map.

   What is a good RTT?

• Since the measurement server is located in the US, the RTTs are higher for other countries. So, the absolute RTT values are not useful outside the United States. The right way to interpret the map is to look at the RTTs in your region and compare the RTTs from neighbouring regions (cities/states).

• e.g. If the median RTT observed at a location in downtown Chicago is 180ms but if it is 300ms in a nearby suburb, then the location in downtown Chicago is experiencing better cellular performance (in terms of RTT) than the suburb in Chicago.