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Packet Size and Duration Dependencies

WLAN standards specify a maximum packet duration (TXTIME) for the various formats. The S1G format additionally specifies the maximum PSDU length (PSDU_LENGTH) and number of symbols (NSYM). These WLAN properties are a function of transmission properties set in WLAN System Toolbox™ configuration objects. The settings of WLAN format-specific configuration objects are validated when the object is used. Command-line feedback informs you when the configuration violates the packet size or duration limits.

This table indicates relevant properties that help determine the packet duration and length for the various WLAN formats. It also provides references to the IEEE® standards for further details.

WLAN FormatLength-Related ValidationRelevant and Dependent Properties
DMG

TXTIME requires validation.

TXTIME is defined by the equations in IEEE Std 802.11ad™ [2], Section 21.12.3.

As specified by aPPDUMaxTime in Table 21-31, the maximum TXTIME is 2 ms.

  1. MCS (dmg_1)

  2. PSDULength

  3. TrainingLength (dmg_1)

  4. PacketType (dmg_1)

  5. BeamTrackingRequest (dmg_1)

(dmg_1) The property helps determine whether the packet is a beam refinement protocol (BRP) packet containing training fields or if it is a general packet signaling the number of fields to append. For more information, see 802.11ad [2], Table 4.

S1G

TXTIME, PSDU_LENGTH, and NSYM require validation.

The equations for all three are defined in draft standard IEEE P802.11ah™/D5.0, Section 24.4.3, and the maximum TXTIME and PSDU_LENGTH is defined in Table 24-37.

In Table 24-37:

  • As specified by aPPDUMaxTime, the maximum TXTIME is 27.92 ms. This TXTIME is the maximum PPDU duration for an S1G_1M PPDU with:

    • A bandwidth of 1 MHz

    • S1G MCS set to 10

    • One spatial stream, limited by a PSDU length of 511 octets.

  • As specified by aPPDUMaxLength, the maximum PSDU_LENGTH is 797,159 octets. This PSDU length is the maximum length in octets for an S1G SU PPDU with:

    • A bandwidth of 16 MHz

    • S1G-MCS set to 9

    • Four spatial streams, limited by 511 data symbols supported by the Length field in the S1G SIG field, excluding the SERVICE field and tail bits.

  • The maximum NSYM is 511.

For TXTIME, the relevant properties are:

  1. ChannelBandwidth

  2. STBC (s1g_1)

  3. GuardInterval

  4. ChannelCoding (MU)

  5. APEPLength (MU)

  6. PSDULength – This property is read-only. When undefined, PSDULength is returned as empty, []. An empty return can happen when the set of property values for the object define an invalid state. (MU)

  7. MCS (MU)

  8. NumSpaceTimeStreams (MU)

  9. NumUsers

For PSDU_LENGTH and NSYM, the relevant properties are:

  1. ChannelBandwidth

  2. STBC (s1g_1)

  3. ChannelCoding (MU)

  4. APEPLength (MU)

  5. PSDULength – This property is read-only. When undefined, PSDULength is returned as empty, []. An empty return can happen when the set of property values for the object define an invalid state. (MU)

  6. MCS (MU)

  7. NumSpaceTimeStreams (MU)

  8. NumUsers

(s1g_1) The property is relevant only when NumUsers = 1.

(MU) The property has multiple values for multi-user operation.

VHT

TXTIME requires validation.

TXTIME is defined by the equations in IEEE Std 802.11ac™-2013 [3], Section 22.4.3 and the maximum TXTIME.

As specified by aPPDUMaxTime in Table 22-29, the maximum TXTIME is 5.484 ms.

  1. ChannelBandwidth

  2. STBC (vht_1)

  3. GuardInterval

  4. ChannelCoding (MU)

  5. APEPLength (MU)

  6. PSDULength – This property is read only. When undefined, it is returned as an empty, [].(MU)

  7. MCS (MU)

  8. NumSpaceTimeStreams (MU)

  9. NumUsers

(vht_1) The property is relevant only when NumUsers = 1.

(MU) The property has multiple values for multi-user operation.

HT

TXTIME requires validation.

TXTIME is defined by the equations in IEEE Std 802.11™-2012 [1], Section 20.4.3.

As specified by aPPDUMaxTime in Table 20-25, the maximum TXTIME is 10 ms.

  1. ChannelBandwidth

  2. GuardInterval

  3. ChannelCoding

  4. PSDULength

  5. MCS

  6. NumSpaceTimeStreams

  7. NumExtensionStreams

non-HT

TXTIME requires validation.

TXTIME is defined by the equations in IEEE Std 802.11-2012 [1], Section 18.4.3.

Based on equation 18–29 and a valid combination of property settings, the maximum TXTIME is 21.936 ms.

  1. Modulation (non-ht_1)

  2. PSDULength

  3. MCS (non-ht_1)

  4. DateRate (non-ht_1)

(non-ht_1) DataRate or MCS might be relevant depending on the Modulation setting.

References

[1] IEEE Std 802.11™-2012 IEEE Standard for Information technology — Telecommunications and information exchange between systems — Local and metropolitan area networks — Specific requirements — Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications.

[2] IEEE Std 802.11ad™-2012 IEEE Standard for Information technology — Telecommunications and information exchange between systems — Local and metropolitan area networks — Specific requirements — Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications — Amendment 3: Enhancements for Very High Throughput in the 60 GHz Band.

[3] IEEE Std 802.11ac™-2013 IEEE Standard for Information technology — Telecommunications and information exchange between systems — Local and metropolitan area networks — Specific requirements — Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications — Amendment 4: Enhancements for Very High Throughput for Operation in Bands below 6 GHz.

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