1. ELEC-E7120 – Wireless Systems Cellular coverage problem in the metro of Helsinki Jere Kaiku (295178) Aapo Poutanen (78999u) Theodosis Makris (465658) Agrasagar Bhattacharyya (463964)

2. Observation and Hypothesis Coverage problem in the metro of Helsinki Sudden change in signal strength from very good to very bad in certain areas(especially in tunnels). When metro trolley starts moving, a huge drop in experienced in QoS can be noted. Few second connection drops when reaching the end of WLAN range and phone switches to cellular data. Group 17

3. Measurement champaign Group 17

4. Graph of the measurements from Ruoholahti to Kulosaari and back 15:40-15:42 at Ruoholahti 15:44 at Kamppi 15:45 at Railwaystation 15:46 at University of Helsinki 15:48 at Hakaniemi 15:50 at Sörnäinen 15:52 at Kalasatama 15:54 at Kulosaari 15:57 at Kalasatama 15:59 at Sörnäinen 16:01 at Hakaniemi 16:03 at University of Helsinki 16:05 at Railwaystation 16:07 at Kamppi 16:09-> at Ruoholahti Group 17

5. Measurements with 1 sec interval from Ruoholahti to Railway station and back Group 17 09:42-09:45 at Ruoholahti 09:47 at Kamppi 09:48-09:55 at Railwaystation 09:56 at Kamppi 09:59 at Ruoholahti

6. Closer look at the strangeness in the tunnel Very short handovers, and finally stuck at very low signal Group 17

7. Analysis 1 Bad coverage in certain areas along the train lines Group 17

8. Solution 1 Group 17 High power eNB

9. Analysis 2 Group 17 The signal gets affected in tunnels Large penetration loss due to the shield of the train

10. Solution 2 Group 17

11. Analysis 3 Group 17 The network faces reduced handover success rate and increased power consumptions of UEs

12. Handover cases Frequent handoverToo late handover Group 17 A B A B

13. Solution 3 – Mobile Relay Nodes Group 17 Backhaul MRN Predictor Antenna

14. THE END Group 17