Peter de Bruin

Improved Latency Performance with GSM/EDGE Continued Evolution

The worlds largest and most widespread cellular technology today is GSM/EDGE. EDGE is capable of offering an attractive solution for 3rd generation cellular services in existing GSM networks. However, the introduction of new and more delay sensitive services may require improved latency performance. Reducing the delay and increasing the bandwidth efficiency in EDGE systems is important for services with stringent latency requirements, such as conversational VoIP, but will be beneficial also to other services. Proposed is to reduce the transmission time interval from 20 ms to 10 ms, in combination with novel procedures for faster feedback. Simulation results show that LLC delays may be reduced by 20-40% depending on traffic scenario. Furthermore, channel resource requirements for VoIP could be substantially reduced.

Network Densification Impact on System Capacity

With the tremendous growth of smartphone penetration, the demand for increased capacity in cellular networks has escalated. The trend is predicted to continue for years to come. One common way to cope with the ever increasing capacity demand is to add cells and densify the networks. Network densification was used before the introduction of LTE and Heterogeneous Networks, and will be even more emphasized with the introduction of 5G, where higher frequency bands with more challenging propagation characteristics, will be utilized. This study shows that in a confined geographical area with a fixed number of users, the user bit rate always increases with network densification. It is also shown that the capacity increase slows down with an increased number of cells, due to the increasing interference from the additional cells. Also, if the path loss exponent increases with distance, a reduced distance between cells reduces the capacity increase.

Higher Order Modulation and Turbo Coding for GSM/EDGE Continued Evolution

GSM/EDGE is the worlds largest and most widespread cellular technology. EDGE offers an attractive solution for 3rd generation cellular services in existing GSM networks. The introduction of new services into an existing network typically leads to increased capacity demands, since more users of different service types need to coexist in limited spectrum, while the existing speech service is required to function at least as well as before. Higher Order Modulation in combination with Turbo Coding is proposed to substantially enhance spectrum efficiency and average user bit rates in GSM/EDGE through improved interference robustness and increased peak bit rates. Simulation results indicate link level gains of 2.5-5.5 dB. When additionally applying incremental redundancy, similar relative improvements are shown. Bit rates can be increased by more than 30%, at C/I levels above 30dB. System performance gains are indicated by average user bit rate enhancements of up to 30-40%, along with substantial gains in spectrum efficiency, up to 40%. It is also shown that system gains are rather insensitive to frequency reuse and whether frequency hopping is applied or not (in sparse reuse scenarios).