In alignment with ETSI 300220v2.3.1, a new “N”-mode physical (PHY) layer has been introduced within the latest draft of EN13757-4:2011 (also called wM-Bus) document. The 75 kHz bandwidth has been split into 6 narrowband channels of 12.5 kHz each. Four channels of 4.8kbps with GFSK and two at 2.4kbps with GFSK modulation have been defined.
A secondary communications link, capable of 19.2kbps with 4-GFSK modulation, has been defined with the purpose of optimizing data throughput in optional multi-hop links (Figure 2).
Figure 2: wM-Bus mode N (as per EN13757-4:2011 draft document)
Field tests with 169MHz systems in France have already proven that the longer achievable range leads to significant simplification of the network architecture. With the proper deployment of data collectors at 169MHz, smart grid networks in Europe without repeaters become a realistic scenario.
Figure 3: wM-Bus N-modes and ETSI 300220v2.3.1 relationship (Source: EN13757-4:2011 Draft)
The new wM-Bus N-mode is explained in Figure 3
; this 169MHz narrowband solution is well suited to become the choice for future gas and water meter installations in several European countries.