Communication networks beyond the capacity crunch

Abstract

This issue of Philosophical Transactions of the Royal Society, Part A represents a summary of the recent discussion meeting 'Communication networks beyond the capacity crunch'. The purpose of the meeting was to establish the nature of the capacity crunch, estimate the time scales associated with it and to begin to find solutions to enable continued growth in a post-crunch era. The meeting confirmed that, in addition to a capacity shortage within a single optical fibre, many other 'crunches' are foreseen in the field of communications, both societal and technical. Technical crunches identified included the nonlinear Shannon limit, wireless spectrum, distribution of 5G signals (front haul and back haul), while societal influences included net neutrality, creative content generation and distribution and latency, and finally energy and cost. The meeting concluded with the observation that these many crunches are genuine and may influence our future use of technology, but encouragingly noted that research and business practice are already moving to alleviate many of the negative consequences.

Keywords: capacity limits; energy; mobile communications; optical communications.

Figure 1.

Evolution of communication capacity with time showing the best reported capacity including reports from scientific publications (green, purple), capacities switched within the core network from commercially available products (red) and data rates offered to residential customers in at least one country (blue). Symbols indicate use of free-space (crosses) or fibre (solid symbols) based optical systems or electronic systems (open symbols). Purple symbols represent spatial multiplexing; while curve fits assume that the compound annual growth rate is 5.75% times the global population in billions (figure 2) with the offset an arbitrary fitting parameter. Data taken from leading international conferences, manufacturers' data sheets and Internet resources.

Figure 2.

Evolution of global population (purple solid line), and compound annual growth rate (green filled circles, raw data smoothed over a minimum of 2 years) of communication capacity confirming correlation between the rate of increase of communication at a distance and population.

Figure 3.

Maximum system throughput as a function of transmission distance assuming a 5 THz total bandwidth without compensation of nonlinearity (blue), with ideal compensation of nonlinearity based on digital signal processing (green) and with compensation of nonlinearity constrained by polarization mode dispersion (red). Horizontal lines show reach limits for polarization multiplexed QPSK (dot), 16QAM (dashed) and 256QAM (solid).