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802.15.4g MR-FSK

The multi-rate and multi-regional frequency shift keying (MR-FSK) provides good transmit power efficiency due to the constant envelope of the transmit signal.

Packet/Frame Structure

802.15.4g MR-FSK signal is generated on a packet/frame basis. A packet shall include SHR, PHR, PSDU parts as defined in the spec and possibly the ramp up & down and idle interval as configured by user. Below is a figure illustrating the structure of a FSK packet. A waveform can include one or more packets, depending on user's setting. When idle interval is set to zero, a continuous (non-bursted) will be generated without any ramp up & down and idle interval.

The PPDU format for MR-MSK is illustrated as follows.

• Format of the MR-FSK PPDU

• Format of the MR-FSK PPDU (optional, if mode switch is enabled)

The modulation for MR-FSK is either a 2- or a 4- level filtered FSK.

802.15.4g-2012 defines various operating modes for MR-FSK using various frequency bands, data rates, modulation and channel spacing. All fields in the MR-FSK PPDU shall use the same symbol rate and modulation order.

Modulation and coding for 802.15.4g MR-FSK

A device shall support operating mode #1 and may additionally support operating modes #2 and #3.

For Japanese bands, a device shall support both modes #1 and #2 and may additionally support operating modes #3 and #4.

Frequency Deviation for 802.15.4g MR-FSK

The nominal frequency deviation is defined as:

Δf = (symbol rate x modulation index)/2

For filtered 2FSK, f_dev = Δf

For filtered 4FSK, f_dev = 3 x Δf

The figure below give the symbol encode for MR-FSK.

Modulation Quality for 802.15.4g MR-FSK

Frequency Deviation Tolerance and Zero Crossing Tolerance are measured to evaluate the modulation quality for MR-FSK.

The following figure show the eye diagrams for filtered 2FSK and filtered 4FSK. More requirements on regulatory compliance, please refer to IEEE 802.15.4g-2012 18.1.5.