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struct iwl_cmd_header -

struct iwl_cmd_header {
};

Members

Description

This header format appears in the beginning of each command sent from the driver, and each response/notification received from uCode.

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struct iwl4965_tx_power - txpower format used in REPLY_SCAN_CMD

struct iwl4965_tx_power {
};

Members

Description

Scan uses only one transmitter, so only one analog/dsp gain pair is needed.

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union iwl4965_tx_power_dual_stream -

union iwl4965_tx_power_dual_stream {
};

Members

Description

Host format used for REPLY_TX_PWR_TABLE_CMD, REPLY_CHANNEL_SWITCH Use __le32 version (struct tx_power_dual_stream) when building command.

Driver provides radio gain and DSP attenuation settings to device in pairs, one value for each transmitter chain. The first value is for transmitter A, second for transmitter B.

For SISO bit rates, both values in a pair should be identical. For MIMO rates, one value may be different from the other, in order to balance the Tx output between the two transmitters.

See more details in doc for TXPOWER in iwl-4965-hw.h.

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struct tx_power_dual_stream -

struct tx_power_dual_stream {
};

Members

Description

Table entries in REPLY_TX_PWR_TABLE_CMD, REPLY_CHANNEL_SWITCH

Same format as iwl_tx_power_dual_stream, but __le32

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struct iwl4965_tx_power_db -

struct iwl4965_tx_power_db {
};

Members

Description

Entire table within REPLY_TX_PWR_TABLE_CMD, REPLY_CHANNEL_SWITCH

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struct iwl4965_ac_qos - - QOS timing params for REPLY_QOS_PARAM

struct iwl4965_ac_qos {
    __le16 cw_min;
    __le16 cw_max;
    u8 aifsn;
    __le16 edca_txop;
};

Members

cw_min

Contention window, start value in numbers of slots. Should be a power-of-2, minus 1. Device's default is 0x0f.

cw_max

Contention window, max value in numbers of slots. Should be a power-of-2, minus 1. Device's default is 0x3f.

aifsn

Number of slots in Arbitration Interframe Space (before performing random backoff timing prior to Tx). Device default 1.

edca_txop

Length of Tx opportunity, in uSecs. Device default is 0.

Description

Device will automatically increase contention window by (2*CW) + 1 for each transmission retry. Device uses cw_max as a bit mask, ANDed with new CW value, to cap the CW value.

Description

Device will automatically increase contention window by (2*CW) + 1 for each transmission retry. Device uses cw_max as a bit mask, ANDed with new CW value, to cap the CW value.

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struct sta_id_modify -

struct sta_id_modify {
    u8 sta_id;
    u8 modify_mask;
};

Members

sta_id

index of station in uCode's station table

modify_mask

STA_MODIFY_*, 1: modify, 0: don't change

Description

Driver selects unused table index when adding new station, or the index to a pre-existing station entry when modifying that station. Some indexes have special purposes (IWL_AP_ID, index 0, is for AP).

modify_mask flags select which parameters to modify vs. leave alone.

Description

Driver selects unused table index when adding new station, or the index to a pre-existing station entry when modifying that station. Some indexes have special purposes (IWL_AP_ID, index 0, is for AP).

modify_mask flags select which parameters to modify vs. leave alone.

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struct iwl_link_qual_general_params -

struct iwl_link_qual_general_params {
};

Members

Description

Used in REPLY_TX_LINK_QUALITY_CMD

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struct iwl_link_qual_agg_params -

struct iwl_link_qual_agg_params {
};

Members

Description

Used in REPLY_TX_LINK_QUALITY_CMD

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struct iwl4965_scan_channel - entry in REPLY_SCAN_CMD channel table

struct iwl4965_scan_channel {
};

Members

Description

One for each channel in the scan list.

Each channel can independently select

1) SSID for directed active scans 2) Txpower setting (for rate specified within Tx command) 3) How long to stay on-channel (behavior may be modified by quiet_time, quiet_plcp_th, good_CRC_th)

To avoid uCode errors, make sure the following are true (see comments under struct iwl4965_scan_cmd about max_out_time and quiet_time): 1) If using passive_dwell (i.e. passive_dwell != 0): active_dwell <= passive_dwell (< max_out_time if max_out_time != 0) 2) quiet_time <= active_dwell 3) If restricting off-channel time (i.e. max_out_time !=0): passive_dwell < max_out_time active_dwell < max_out_time

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struct iwl4965_ssid_ie - directed scan network information element

struct iwl4965_ssid_ie {
};

Members

Description

Up to 4 of these may appear in REPLY_SCAN_CMD, selected by "type" field in struct iwl4965_scan_channel; each channel may select different ssids from among the 4 entries. SSID IEs get transmitted in reverse order of entry.

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HD_TABLE_SIZE -

HD_TABLE_SIZE ( 11)

Arguments

Description

This command sets up the Rx signal detector for a sensitivity level that is high enough to lock onto all signals within the associated network, but low enough to ignore signals that are below a certain threshold, so as not to have too many "false alarms". False alarms are signals that the Rx DSP tries to lock onto, but then discards after determining that they are noise.

The optimum number of false alarms is between 5 and 50 per 200 TUs (200 * 1024 uSecs, i.e. 204.8 milliseconds) of actual Rx time (i.e. time listening, not transmitting). Driver must adjust sensitivity so that the ratio of actual false alarms to actual Rx time falls within this range.

While associated, uCode delivers STATISTICS_NOTIFICATIONs after each received beacon. These provide information to the driver to analyze the sensitivity. Don't analyze statistics that come in from scanning, or any other non-associated-network source. Pertinent statistics include:

From "general" statistics (struct statistics_rx_non_phy):

(beacon_energy_[abc] & 0x0FF00) >> 8 (unsigned, higher value is lower level) Measure of energy of desired signal. Used for establishing a level below which the device does not detect signals.

(beacon_silence_rssi_[abc] & 0x0FF00) >> 8 (unsigned, units in dB) Measure of background noise in silent period after beacon.

channel_load uSecs of actual Rx time during beacon period (varies according to how much time was spent transmitting).

From "cck" and "ofdm" statistics (struct statistics_rx_phy), separately:

false_alarm_cnt Signal locks abandoned early (before phy-level header).

plcp_err Signal locks abandoned late (during phy-level header).

NOTE

Both false_alarm_cnt and plcp_err increment monotonically from beacon to beacon, i.e. each value is an accumulation of all errors before and including the latest beacon. Values will wrap around to 0 after counting up to 2^32 - 1. Driver must differentiate vs. previous beacon's values to determine # false alarms in the current beacon period.

Total number of false alarms = false_alarms + plcp_errs

For OFDM, adjust the following table entries in struct iwl_sensitivity_cmd (notice that the start points for OFDM are at or close to settings for maximum sensitivity):

START / MIN / MAX HD_AUTO_CORR32_X1_TH_ADD_MIN_INDEX 90 / 85 / 120 HD_AUTO_CORR32_X1_TH_ADD_MIN_MRC_INDEX 170 / 170 / 210 HD_AUTO_CORR32_X4_TH_ADD_MIN_INDEX 105 / 105 / 140 HD_AUTO_CORR32_X4_TH_ADD_MIN_MRC_INDEX 220 / 220 / 270

If actual rate of OFDM false alarms (+ plcp_errors) is too high (greater than 50 for each 204.8 msecs listening), reduce sensitivity by *adding* 1 to all 4 of the table entries above, up to the max for each entry. Conversely, if false alarm rate is too low (less than 5 for each 204.8 msecs listening), *subtract* 1 from each entry to increase sensitivity.

For CCK sensitivity, keep track of the following:

1). 20-beacon history of maximum background noise, indicated by (beacon_silence_rssi_[abc] & 0x0FF00), units in dB, across the 3 receivers. For any given beacon, the "silence reference" is the maximum of last 60 samples (20 beacons * 3 receivers).

2). 10-beacon history of strongest signal level, as indicated by (beacon_energy_[abc] & 0x0FF00) >> 8, across the 3 receivers, i.e. the strength of the signal through the best receiver at the moment. These measurements are "upside down", with lower values for stronger signals, so max energy will be *minimum* value.

Then for any given beacon, the driver must determine the *weakest* of the strongest signals; this is the minimum level that needs to be successfully detected, when using the best receiver at the moment. "Max cck energy" is the maximum (higher value means lower energy!) of the last 10 minima. Once this is determined, driver must add a little margin by adding "6" to it.

3). Number of consecutive beacon periods with too few false alarms. Reset this to 0 at the first beacon period that falls within the "good" range (5 to 50 false alarms per 204.8 milliseconds rx).

Then, adjust the following CCK table entries in struct iwl_sensitivity_cmd (notice that the start points for CCK are at maximum sensitivity):

START / MIN / MAX HD_AUTO_CORR40_X4_TH_ADD_MIN_INDEX 125 / 125 / 200 HD_AUTO_CORR40_X4_TH_ADD_MIN_MRC_INDEX 200 / 200 / 400 HD_MIN_ENERGY_CCK_DET_INDEX 100 / 0 / 100

If actual rate of CCK false alarms (+ plcp_errors) is too high (greater than 50 for each 204.8 msecs listening), method for reducing

sensitivity is

1) *Add* 3 to value in HD_AUTO_CORR40_X4_TH_ADD_MIN_MRC_INDEX, up to max 400.

2) If current value in HD_AUTO_CORR40_X4_TH_ADD_MIN_INDEX is < 160, sensitivity has been reduced a significant amount; bring it up to a moderate 161. Otherwise, *add* 3, up to max 200.

3) a) If current value in HD_AUTO_CORR40_X4_TH_ADD_MIN_INDEX is > 160, sensitivity has been reduced only a moderate or small amount; *subtract* 2 from value in HD_MIN_ENERGY_CCK_DET_INDEX, down to min 0. Otherwise (if gain has been significantly reduced), don't change the HD_MIN_ENERGY_CCK_DET_INDEX value.

b) Save a snapshot of the "silence reference".

If actual rate of CCK false alarms (+ plcp_errors) is too low (less than 5 for each 204.8 msecs listening), method for increasing

sensitivity is used only if

1a) Previous beacon did not have too many false alarms 1b) AND difference between previous "silence reference" and current "silence reference" (prev - current) is 2 or more, OR 2) 100 or more consecutive beacon periods have had rate of less than 5 false alarms per 204.8 milliseconds rx time.

Method for increasing sensitivity

1) *Subtract* 3 from value in HD_AUTO_CORR40_X4_TH_ADD_MIN_INDEX, down to min 125.

2) *Subtract* 3 from value in HD_AUTO_CORR40_X4_TH_ADD_MIN_MRC_INDEX, down to min 200.

3) *Add* 2 to value in HD_MIN_ENERGY_CCK_DET_INDEX, up to max 100.

If actual rate of CCK false alarms (+ plcp_errors) is within good range (between 5 and 50 for each 204.8 msecs listening):

1) Save a snapshot of the silence reference.

2) If previous beacon had too many CCK false alarms (+ plcp_errors), give some extra margin to energy threshold by *subtracting* 8 from value in HD_MIN_ENERGY_CCK_DET_INDEX.

For all cases (too few, too many, good range), make sure that the CCK detection threshold (energy) is below the energy level for robust detection over the past 10 beacon periods, the "Max cck energy". Lower values mean higher energy; this means making sure that the value in HD_MIN_ENERGY_CCK_DET_INDEX is at or *above* "Max cck energy".

Driver should set the following entries to fixed values

HD_MIN_ENERGY_OFDM_DET_INDEX 100 HD_BARKER_CORR_TH_ADD_MIN_INDEX 190 HD_BARKER_CORR_TH_ADD_MIN_MRC_INDEX 390 HD_OFDM_ENERGY_TH_IN_INDEX 62

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struct iwl4965_sensitivity_cmd -

struct iwl4965_sensitivity_cmd {
    __le16 control;
    __le16 table[HD_TABLE_SIZE];
};

Members

control

(1) updates working table, (0) updates default table

table[HD_TABLE_SIZE]

energy threshold values, use HD_* as index into table

Description

Always use "1" in "control" to update uCode's working table and DSP.

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PHY_CALIBRATE_DIFF_GAIN_CMD -

PHY_CALIBRATE_DIFF_GAIN_CMD ( 7)

Arguments

Description

This command sets the relative gains of 4965's 3 radio receiver chains.

After the first association, driver should accumulate signal and noise statistics from the STATISTICS_NOTIFICATIONs that follow the first 20 beacons from the associated network (don't collect statistics that come in from scanning, or any other non-network source).

DISCONNECTED ANTENNA

Driver should determine which antennas are actually connected, by comparing average beacon signal levels for the 3 Rx chains. Accumulate (add) the following values over 20 beacons, one accumulator for each of the chains a/b/c, from struct statistics_rx_non_phy:

beacon_rssi_[abc] & 0x0FF (unsigned, units in dB)

Find the strongest signal from among a/b/c. Compare the other two to the strongest. If any signal is more than 15 dB (times 20, unless you divide the accumulated values by 20) below the strongest, the driver considers that antenna to be disconnected, and should not try to use that antenna/chain for Rx or Tx. If both A and B seem to be disconnected, driver should declare the stronger one as connected, and attempt to use it (A and B are the only 2 Tx chains!).

RX BALANCE

Driver should balance the 3 receivers (but just the ones that are connected to antennas, see above) for gain, by comparing the average signal levels detected during the silence after each beacon (background noise). Accumulate (add) the following values over 20 beacons, one accumulator for each of the chains a/b/c, from struct statistics_rx_non_phy:

beacon_silence_rssi_[abc] & 0x0FF (unsigned, units in dB)

Find the weakest background noise level from among a/b/c. This Rx chain will be the reference, with 0 gain adjustment. Attenuate other channels by

finding noise difference

(accum_noise[i] - accum_noise[reference]) / 30

The "30" adjusts the dB in the 20 accumulated samples to units of 1.5 dB. For use in diff_gain_[abc] fields of struct iwl_calibration_cmd, the driver should limit the difference results to a range of 0-3 (0-4.5 dB), and set bit 2 to indicate "reduce gain". The value for the reference (weakest) chain should be "0".

diff_gain_[abc] bit fields:

2

(1) reduce gain, (0) increase gain 1-0: amount of gain, units of 1.5 dB

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