Streamlining HSUPA TTI Lengths without Compromising HSUPA Capacity

This paper proposes a s.c. 2 ms range extension scheme for High Speed Uplink Packet Access (HSUPA) networks to avoid potential coverage problems and usage of multiple TTI lengths. With range extension UEs in poor radio conditions are configured to send bundles of 2 ms TTI transmissions without HARQ feedback to improve their coverage. This paper analyzes the performance of range extension in comparison with normal 2 ms TTI performance with multiple inter-site distances. The analysis is conducted considering VoIP performance due to its high sensitivity to additional delays and packet loss. The results acquired by using system level simulation tool indicate that using 2 ms range extension can improve system capacity in larger cells where normal 2 ms TTI can result into coverage problems. Moreover, utilizing repeated 2 ms TTIs instead 10 ms TTIs enables increased battery saving opportunities when UL DTX is applied.