Data rates in mobile networks are expected to increase 40-fold from 2010 to 2015, mostly due to the trend that Internet access is getting increasingly wireless using smartphones and tablet devices. The enormous traffic demand poses a challenge for the new 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) system, where the initial Release 8 rolled out recently. The forthcoming LTE-Advanced standard (Release 10) will enable the aggregation of multiple frequency bands to increase the data rate. Traditional solutions need more spectrum or a higher density of base stations. An advanced approach is based on multi-cell signal processing where inter-cell interference is reduced using so-called coordinated multi-point (CoMP) techniques. For the realization of the X2 interfaces for the connection of the LTE-A base stations fiber based connections with 10G Ethernet interfaces are an option. The CoMP approaches in general have hard requirements for the end-to-end latencies between the base stations. This paper will show a possible mobile backhaul topology, where adjacent base stations can have a relative long physical connection due to hops or fiber length. Such longer paths can cause higher latencies not only by transmission but also by switching and queuing over several nodes. We will discuss an analytical estimation of end-to-end latencies in multi node networks depending on the amount of hops and arriving frames. Further on these results will be compared to simulations of a packet switched network. The limits and requirements of the switches based on a 10G Ethernet approach will be presented as well.
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