Ulrich Rehfuess

Comparing frequency planning against 1/spl times/3 and 1/spl times/1 re-use in real frequency hopping networks

On the one hand, the potential of radio link control options like frequency hopping, power control and discontinuous transmission for capacity increase in GSM mobile radio networks has been extensively studied by several authors using computer simulations in homogeneous hexagonal networks. Unfortunately, some idealistic assumptions on these network models have a substantial drawback on the practical relevance of the simulation results. On the other hand, many field trials and regular network operation have proven very good results in terms of both network quality and capacity when applying radio link options in tight frequency re-use. But there, systematic investigations are hardly feasible. Therefore, we present results of close-to-reality simulations of FH networks showing that FH, PC and DTX can largely improve system capacity in real non-homogeneous networks by as much as 200%. We systematically investigate both advanced frequency assignments at varying re-use and frequency assignments in cluster 1/spl times/3 and 1/spl times/1. Our results reveal some aspects contrasting widely spread views on implementing FH in real networks. From our investigations we deduct recommendations concerning the optimum approach of using frequency hopping, power control and discontinuous transmission in GSM networks.

Estimating and comparing the upper bounds on the capacity gain from different smart antenna concepts in GSM mobile radio networks

The capacity of GSM mobile radio networks using various smart antenna concepts is investigated by means of computer simulations. The values derived are compared with those of a GSM network with currently available features such as frequency hopping (FH), power control (PC) and discontinuous transmission (DTX) to estimate the additional benefit from smart antennas.

Estimating the gains of adaptive antenna systems for GPRS and EDGE data services in GSM networks

We present a fast and efficient approach to estimate the data throughput over the air interface in packet data services such as the emerging GPRS and EGPRS in GSM mobile radio networks. By using link level performance data and C/I distributions from previously run system level simulations we obtain data rate distributions without re-running tedious system level simulations for packet data. We apply the method to the estimation of the benefits that adaptive antennas add in the GPRS and EGPRS packet data services. Furthermore, the effect of power control is studied by this method. The obtained results yield both valuable insight into performance issues of mobile packet data transmission and benchmarks for double-checking results of precise system level simulations with comprehensive modeling of both interference and packet data protocols.