3.2.1 Abstract Data Model

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This section describes a conceptual model of possible data organization that an implementation maintains to participate in this protocol. The described organization is provided to facilitate the explanation of how the protocol behaves. This document does not mandate that implementations adhere to this model as long as their external behavior is consistent with that described in this document.

The data elements required in typical sink implementations are:

  • Support Level: The level of diagnostics support as returned in the Diag_Support_Level field in a Connect Message-specific header. The value of this field controls the sink's response to the Collect Data Message (section 2.2.2.3).

  • Network Interface Object: Each network interface object uniquely represents a specific network interface and stores the state and statistics related to that interface.

    • Wireless Connected: A Boolean value indicating that the sink device is connected to a wireless access point on the associated network interface. The value of this field controls the sink's response to the Connect Message (section 2.2.2.1) and the Get BSS List Message (section 2.2.2.7).

    • Wireless Statistics History: This data element specifies a collection of statistical counters for the wireless network interface on the sink device. This history buffer is normally implemented as a circular-buffer.

      All statistical values MUST be sampled at 250-millisecond intervals. Devices MUST maintain at least 30 seconds worth of history, which equates to 120 rows.

      Each row in the collection MUST contain the following counters:

      • RSSI: This is the RSSI level of the wireless network interface, in dBm. The normal range for an RSSI value is -10 dBm through -200 dBm.

      • Link Speed: This is the link speed of the wireless network interface in bits per second (bps) units.

      • Retry Delta: This counter represents the change in "number of MSDU/MMPDUs successfully transmitted after one or more retransmissions" for the IEEE 802.11 [IEEE802.11-2007] network interface, relative to that from the previous interval.

      • Transmitted Delta: This counter represents the change in "number of MPDUs with an individual address in the address 1 field and MPDUs that have a multicast address with types Data or Management" for the IEEE 802.11 [IEEE802.11-2007] network interface, relative to that from the previous interval.

      • FCS Error Delta: This counter represents the change in "number of times an FCS error has been detected in a received MPDU" for the IEEE 802.11 [IEEE802.11-2007] network interface, relative to that from the previous interval.

      • Received Delta : This counter represents the change in "number of successfully received Data or Management MPDUs" for the IEEE 802.11 [IEEE802.11-2007] network interface, relative to that from the previous interval.

    • Sample Index: This field counts the total number of samples that have, to date, been recorded into the Wireless Statistics History.

    • Normal Send Model History: This data element specifies a collection of scores, each calculated by the formula (Retry Delta / Transmitted Delta) from a row in the Wireless Statistics History. These scores are then used to maintain the average and variance of what could be considered the "normal" wireless condition. This history buffer is normally implemented as a circular-buffer.

      Devices MUST maintain at least 8 seconds worth of history, which equates to 32 rows.

    • Normal Receive Model History: This data element specifies a collection of scores, each calculated by the formula (FCS Error Delta / Received Delta) from a row in the Wireless Statistics History. These scores are then used to maintain the average and variance of what could be considered the "normal" wireless condition. This history buffer is normally implemented as a circular-buffer.

      Devices MUST maintain at least 8 seconds worth of history, which equates to 32 rows.

    • Send Model Average: This field is recomputed each time Normal Send Model History is updated. It is the average for all the scores.

    • Send Model Variance: This field is recomputed each time Normal Send Model History is updated. It is the variance for all the scores.

    • Receive Model Average: This field is recomputed each time Normal Receive Model History is updated. It is the average for all the scores.

    • Receive Model Variance: This field is recomputed each time Normal Receive Model History is updated. It is the variance for all the scores.

    • BSS List: This data element specifies a collection of entries, each of which identifies the properties of an IEEE 802.11 [IEEE802.11-2007] BSS or wireless network as seen by scanning the wireless radio on the sink device. Each entry is the same as the BssDesc (section 2.2.2.8.1) information returned in the Get BSS List Message-specific header.

    • BSS List Updated: This Boolean field is used to indicate if an attempt was ever made to update the BSS List.

    • Last BSS Scan Time: This field specifies the last time at which the BSS List was updated. This value prevents excessive query for the IEEE 802.11 [IEEE802.11-2007] BSS List which can severely impact the power footprint profile on the sink device.

      Devices MUST be prepared to update the BSS List at least once every 60 seconds.

  • Diagnostic Session: Each Diagnostic Session stores the qWave-WD related states that are relevant to a specific TCP connection accepted from the initiator device. Each Diagnostic Session MUST have the following fields:

    • Handshaking: A Boolean value indicating that the sink is still handshaking with the initiator and is thus not prepared to accept certain messages.

    • Socket: This field identifies the network socket object used to communicate with the initiator device. Every message received from the network is correlated back to a Diagnostic Session using this object.

Note The previous conceptual data can be implemented by using a variety of techniques. An implementation can implement such data in any way.