Bluetooth Core Specification

Table 3.1 outlines the set of commands which can be received by the IUT and the corresponding response events that can be transmitted by the IUT.

Command packet formats are shown in Figure 3.1 and Figure 3.2.

Figure 3.1: Command message format for LE_Transmitter_Test and LE_Receiver_Test commands

Figure 3.2: Command message format for LE_Test_Setup and LE_Test_End commands

If an AoD Constant Tone Extension is selected when transmitting, Control 0x08 shall be used before starting the test. If an AoA Constant Tone Extension is selected when receiving, Controls 0x07 and 0x08 shall be used before starting the test.

Control 0x07 does not affect receiving AoD Constant Tone Extensions or any transmissions. Control 0x08 does not affect transmitting AoA Constant Tone Extensions or receiving AoD Constant Tone Extensions.

In the receiver test, the CTEInfo field specified using Control 0x06 indicates the expected type and length of the Constant Tone Extension. If either the length or type of the Constant Tone Extension in a received LE Test packet does not match the expected value, then the IUT shall discard that packet.

LE_Transmitter_Test and LE_Receiver_Test commands:

The LE_Test_Status event packet format is as shown in Figure 3.4.

Figure 3.4: LE_Test_Status event

The LE_Packet_Report event packet format is shown in Figure 3.5. The Packet Count parameter indicates the number of received LE Test packets. The Packet Count in the LE_Packet_Report event ending a transmitter test shall be 0.

Figure 3.5: LE_Packet_Report event

LE test packets and LE CS test packets shall not use whitening. 

LE test packets shall have ‘10010100100000100110111010001110’ (in transmission order) as the synchronization word. The preamble for all LE test packets is thus ‘10101010’ (in transmission order) when the implementation under test is configured for the LE 1M PHY, ‘1010101010101010’ (in transmission order) if the implementation under test is configured for the LE 2M PHY, and the preamble described in [Vol 6] Part B, Section 2.2.1 if the implementation under test is configured for the LE Coded PHY.

LE CS test packets use Access Addresses (CS_SYNC Words) as defined by the HCI_LE_CS_Test command, [Vol 4] Part E, Section 7.8. 

The CRC shift register shall be preset with 0x555555 for every LE test packet. The CRC portion is not applicable for LE CS test packets. 

The LE test packet PDU consists of an 8-bit header, an 8-bit length field, an optional 8-bit CTEInfo field, and a variable size payload. Its structure is as shown in Figure 4.4 and Figure 4.5.

Figure 4.4: LE Test packet PDU structure

Figure 4.5: LE Test packet header and length field structure

The first four bits of the PDU header field indicate the payload content type as defined in Table 4.1. The CTEInfo Present (CP) field of the PDU header indicates whether the CTEInfo field is present and therefore whether the test packet has a Constant Tone Extension. If the CP field is 0, then no CTEInfo field is present and there is no Constant Tone Extension in the test packet. If the CP field is 1, then the CTEInfo field is present and the test packet includes a Constant Tone Extension. The CTEInfo field is defined in [Vol 6] Part B, Section 2.5.2. The length field expresses the Payload length in bytes.

Example: For LE test packets with 0x0F payload contents (‘11110000’ in transmission order) and with an LE test packet payload length of 37 bytes (296 bits), the LE test packet header and length type field will be ‘1000000010100100’ in transmission order.

The LE test packet payload content alternatives required for the Bluetooth Low Energy RFPHY conformance tests are:

PRBS9:

A 9-bit pseudorandom binary sequence used for wanted signal payload content. The PRBS9 sequence repeats itself after the (2⁹ -1 = 511) bit. The PRBS9 sequence may be generated in a nine stage shift register whose 5^th and 9^th stage outputs are XORed (see Figure 4.6) and the result is fed back to the input of the first stage. The sequence begins with the first ONE of 9 consecutive ONEs (i.e. the shift register is initialized with nine ONEs).

Figure 4.6: Linear feedback shift register for generation of the PRBS9 sequence

The same pseudorandom sequence of bits shall be used for each transmission (i.e. the packet is repeated).

PRBS15:

A 15-bit pseudorandom binary sequence that is used for the interfering signal and can optionally be used for wanted signal payload content. The PRBS15 sequence repeats itself after the (2¹⁵ -1 = 32767) bit. The PRBS15 sequence may be generated in a fifteen stage shift register whose 14th and 15th stage outputs are XORed (see Figure 4.7) and the result is fed back to the input of the first stage. The sequence begins with the first ONE of 15 consecutive ONEs (i.e., the shift register is initialized with fifteen ONEs).

This PRBS15 definition is consistent with ITU T-REC-01 150-199605-I. SERIES O: SPECIFICATIONS OF MEASURING EQUIPMENT - Equipment for the measurement of digital and analogue/digital parameters.

Figure 4.7: Linear feedback shift register for generation of the PRBS15 sequence

The same pseudorandom sequence of bits shall be used for each transmission (i.e. the packet is repeated).

10101010:

Repeated sequence of alternating 1’s and 0’s, starting at the first payload bit and ending at the start of the first bit in the CRC. This pattern is used to verify the frequency deviation and the Gaussian filtering properties of the transmitter modulator.

11110000:

Repeated sequence of alternating 0’s and 1’s in groups of four (i.e. 1111000011110000...), starting at the first payload bit and ending at the start of the first bit in the CRC. This pattern is used to verify the frequency deviation and the Gaussian filtering properties of the transmitter modulator.

While in LE direct TX mode, LE test packets shall be transmitted from the EUT with a packet interval I(L) as defined below; see the top half of Figure 4.8 for reference.

While in LE direct RX mode, the nominal packet interval of the LE test packets transmitted from the tester is I(L), but the tester packet interval may be extended to a maximum of T(L) upon change of the dirty transmitter parameter settings and during verification of the EUT PER reporting functionality. See the bottom half of Figure 4.8 for reference.

Figure 4.8: LE Test packet interval in LE Direct Test mode

For an LE Test packet length of L µs, I(L) = $⌈\left(L+249\right)÷625⌉$ × 625 µs and T(L) = max (I(L) + 10 ms, 12.5 ms).

The Constant Tone Extension is an optional field that consists of a constantly modulated series of unwhitened 1s. It is 16 to 160 bits when operating at 1 Msym/s modulation or 32 to 320 bits when operating at 2 Msym/s modulation. The Constant Tone Extension is not included in CRC or MIC calculations. The Constant Tone Extension shall only be present on the LE Uncoded PHYs.

If Direct Test Mode is being used over HCI and a Constant Tone Extension is present in a received packet, the Controller may generate events containing IQ samples of the Constant Tone Extension (see [Vol 4] Part E, Section 7.7.65.21).

The CS trailer is a sequence of 4 bits, alternating between 0 and 1 bits. The trailer is 1010 (in transmission order) when the most significant bit of the CS Access Address is a 0, and 0101 when the most significant bit of the CS Access Address is a 1.

The CS Test packet payload is defined by the HCI_LE_­CS_­Test command, [Vol 4] Part E, Section 7.8. The payload length shall be either 32, 64, 96, or 128 bits, defined in [Vol 6] Part H, Section 2.5. There are no associated PDU header or PDU length fields for LE CS Test packet.

In some instances Channel Sounding tests involve exchanges between initiator and reflector devices. In these cases both devices shall operate using active clock accuracy as described in [Vol 6] Part B, Section 4.2.1.