HK1097664A - Method and apparatus for network management using perceived signal to noise and interference indicator - Google Patents

Description

Method and apparatus for network management of noise and interference indicators using perceived signals

Technical Field

The present invention relates generally to network management, and more particularly to using an observed signal parameter obtained at a receiving end as a signal-to-noise (and interference) indicator (PSNI) for facilitating network management.

Background

This specification contains the following acronyms in english:

AP Access point (access point)

BER bit error Rate (bit error rate)

CCK complementary code shift key (complementary code keying)

DSSS direct sequence spread spectrum (direct sequence spread spectrum)

EIRP equivalent isotropic radiated power (equivalent isotropic radiated power)

ERP effective radiation power (effective radial power)

FEC forward error correction (forward error correction)

FER frame error rate (frame error rate)

MIB management database (management information base)

OFDM orthogonal frequency multiple division (orthogonal frequency division multiplexing)

PBCC packet binary convolutional coding (packet binary convolutional coding)

PHY physical layer (physical layer)

PLCP physical layer conversion communication protocol (physical layer conversion protocol)

PMD physical media dependence (physical media dependent)

PPDU PLCP communication protocol data unit (PLCP protocol data unit)

PSK phase shift key (phase shift keying)

PSNI sense signal to noise indication (noise indication)

RPI received power indicator (received power indicator)

RSSI received signal strength indicator (received signal strength indicator)

SQ Signal quality (signal quality)

STA base station (station)

Today's IEEE standard 802.11 is granted the functionality to provide interfaces, measurements, and procedures to support higher layers with efficient network management. Currently, the 802.11 standard has defined a number of physical parameters, none of which is entirely suitable for the purpose of network management. One example of a measurable parameter is Received Signal Strength Indicator (RSSI), which is a reportable parameter for each received frame but is not shown in the standard and is not completely specified. The standard contains some definitions in view of RSSI, but it retains some limitations that RSSI imposes on the use of network management, since RSSI parameters from different base Stations (STAs) may not be uniformly defined and therefore cannot be compared.

The second proposed measurable parameter is Signal Quality (SQ), which is also exactly a non-quantized indicator of code synchronization, but is only applicable to DSSS PHY modulation and not to OFDM PHY modulation. Another measurable parameter is the RPI histogram, which, if quantized or indicated, cannot be targeted for measurement on any bridge. The RPI histogram measures channel power from all resources, including 802.11 resources, radar, and all other interferers, which is not helpful in relying on the RPI histogram as a control parameter.

The current standard defines the indication of received signal strength based mainly on measurements of AP signals:

(1) on the same channel, the same physical layer, and the same base station; and

(2) on different channels, the same physical layer, and the same base station.

Importantly, measurements involving different physical layers and the same or different base stations, even if required, are not currently proposed in the standard.

Network management requires comparative PHY measurements, such as for use in disconnection decisions. The following form is comparative PHY measurements.

1. AP signals on the same channel, same PHY, in the same STA are compared.

2. AP signals on the same channel, same PHY, in different STAs are compared.

3. AP signals on different channels, on the same PHY, in the same STA are compared.

4. AP signals on different channels, on the same PHY, in different STAs are compared.

5. AP signals on different PHYs in different STAs were compared.

6. AP signals on different PHYs in the same STA are compared.

The comparative measurement is very important for the disconnection determination of network management.

RSSI, as currently defined, provides only the above categories (1) and (3). RSSI is a measure of the RF energy received by the DSSSPHY or OFDM PHY. The RSSI indication is provided for up to eight bits (256 levels). The allowable value of RSSI ranges from zero to the maximum value of RSSI. This parameter is measured by the PHY's secondary layer of energy observed on the antenna used to receive the current PPDU. RSSI is measured during reception of the PLCP preamble. RSSI is intended to be used in a relative manner and is a monotonically increasing function of received power.

CCK, ER-PBCC: as depicted at 18.4.5.11 for an eight-bit value RSSI.

ERP-OFDM, DSSS-OFDM, the eight bits range in value from zero to the maximum of RSSI as depicted in 17.2.3.2.

Some limitations of RSSI indicators are: RSSI is a monotonic, relative power indicator at the antenna connection point that indicates the sum of the desired signal, noise and interference power. In high interference environments, RSSI is not a suitable indicator of required signal quality. RSSI does not fully indicate: there are no cell definitions and no performance requirements (accuracy, fidelity, testability). Because so few are specified with respect to RSSI, extensive implementation variations are certainly considered to have existed. It is not possible to compare the RSSI of different products and perhaps even different channels/bandwidths within the same product.

Although RSSI has limited use within one known PHY for estimating the AP option, it is not used to compare different PHYs. RSSI must be re-measured for DSSS and OFDM PHYs. RSSI is clearly useless in load balancing and load shifting for network management, and the RSSI of one base station is indeed independent of the RSSI of any other base station.

Disclosure of Invention

The present invention provides a network management method (PSNI) using a signal parameter, which is a perceptual signal-to-noise indication; and RSSI is not used, which has a number of serious limitations on indication. Preferably, but not necessarily, the allowable value of the PSNI parameter may be 0 to 255, for example.

Drawings

The present invention will be further understood from the following detailed description of various preferred embodiments:

FIG. 1 is an option for PHY metrology of the present invention;

FIG. 1a is a flow chart of a technique of obtaining an input to an FEC decoder in accordance with the present invention;

FIG. 2 is the PSNI specified in the BER curve; and

fig. 3 is an example PSNI description point.

Detailed Description

It is desirable to provide a method of network management that takes into account comparative measurements of AP signals in all different scenarios involving different physical layers and the same or different base stations.

Described later is a specific demodulator, a subjective estimator of perceived S/(N + I) specified by a quantized FER indicator. The following is recorded in the description of the embodiments.

All digital demodulators use a tracking loop and complex post-processing to demodulate the received symbols. Many internal demodulator parameters are proportional to the perceived S/(N + I). Some examples are:

PSK: fundamental frequency phase jitter, fundamental frequency error vector value (EVM)

And (4) DSSS: spreading code correction quality

OFDM: frequency tracking and channel tracking stability

The demodulator internal parameters are available on a frame-by-frame basis. The demodulator parameters proportional to analog S/(N + I) are invariant with respect to data rate. The same parameters may be used at any data rate.

Demodulator internal parameters may be specified and corrected in a controlled environment that is related to actual FER performance at more than two operating points defined by rate, modulation, and FEC. Such demodulator internal parameters estimate FER performance in interference and interference-free (noise-only) environments and can be used as a standard for PSNI. As a useful PSNI indicator, it is not necessary to specify which demodulator internal parameter is used as the standard for the demodulator, but it is sufficient to state how the quantized indicator is related to FER.

Note that the following matters are related to the inventive use of PSNI on network management:

PSNI is specified as RSSI as an eight-bit unsigned value with a monotonic increase of increasing S/(N + I).

PSNI is logarithmically amplified for perceptual S/(N + I). PSNI is a demodulator internal parameter that is built into a fast estimator that provides FER.

PSNI outputs that are specified to span a range are defined by two signal product dots: the first point is at a minimum available signal quality level and the second point is at a maximum available signal quality level.

An output value and an accuracy of the output value are specified for at least two FER points, and one FER point is specified for each effective modulation, FEC and data rate combination.

The PSNI range may span the portion of the S/(N + I) operating range below 40db to cover high firs at data rates from 1 to 54Mbps, but higher or lower range distances may be used.

The PSNI indicator is a measure of the perceived, post-processed signal to noise and interference (S/(N + I)) ratio in the demodulator. The allowable value range for the perceptual signal-to-noise indicator (PSNI) parameter is from 0 to 255 (i.e., eight binary bits). This parameter is measured by a PHY sublayer of perceived signal quality observed after RF down conversion (down conversion) and is derived from a demodulator internal digital signal processing parameter used to receive the current frame. PSNI is measured on the preamble of PLCP and on all received frames. PSNI attempts to use a relative approach and it is an observed monotonically increasing logarithmic function of S/(N + I). PSNI accuracy and range are specified at the minimum of two different FER operating cases. Fig. 3 provides an example illustration point for PSNI amplification to a range of 43 dB.

Fig. 1 shows PHY measurement options that may be used as a PSNI indicator. Referring to the receiving apparatus 10 of fig. 1, the following general comments are valid for a wide range of current modulation and coding techniques. The signal to noise ratio at points a and B is theoretically the same but may actually be slightly different due to increased losses at the radio front end (radio front end) 12. The signal to noise ratio after analog to digital conversion at the a/D converter 14 is also theoretically the same, with a slight increase in noise with respect to quantization error.

Thus, in a high performance system, there is only a slight difference between the noise-to-signal ratio at point a and the noise-to-signal ratio input to the demodulator 16 and the tracking loop. In a simple and low performance system, there may be a significant difference between the noise-to-signal ratio at point a and the noise-to-signal ratio input to the demodulator 16. The noise-to-signal ratio at the output of the demodulator 16 (point C) cannot be directly observed by the Bit Error Rate (BER). The BER at point C is related to the signal-to-noise ratio at point B according to a demodulator performance curve that is used to cause loss of performance of the actual demodulator.

Similarly, the output at the FEC decoder 18 (point D) is related to the FEC decoder input in terms of an FEC decoder performance curve that is used to generate the actual FEC decoder performance penalty. The Frame Error Rate (FER) at point E of the frame check function 20 is a direct mathematical function of the BER and error distribution statistics at point D. The loss performed has generally no direct relation to the frame check. In general, for lower BERs, FEC is equal to BER multiplied by the bit size of the frame.

The frame check function 20 of the receiving device 10 in fig. 1 may be performed with a frame sync check. In most practical designs, each frame contains a synchronization check that indicates (with high reliability) whether the block was received correctly. Most common parity Checking is a Cyclic Redundancy Check (CRC), but other techniques are possible and acceptable. If no frame sync check is used, the FER is estimated using a BER derived from a function of the FEC decoder 18. The BER input derived from the FEC decoder 18 function can be done in a known way, summarized as follows (see fig. 1 a):

the output of the FEC decoder is generally correct. Thus, the output is obtained and recorded (steps S1 and S2). The coding rules of the FEC are used to create a model of the correct input bits (step S3) and each bit is compared with the corresponding bit actually input to the FEC decoder and recorded (step S4). Each comparison is incremented by one count value (step S5). Each mismatch (step S6) represents a cumulative input bit error (step S7). The resulting BER (steps S9 and S10) may then be used to estimate the observed FER (step S11) from the actual performance curve of the FEC decoder. This comparison (whether there is an error-step S6) continues until a count value N is reached (step S8), at which point the count value at step S7 is considered to be BER (step S9).

In this approach, using the actual implementation penalty in the theoretical performance curve allows one to correlate the signal-to-noise measurements at any point to the signal-to-noise measurements at other points.

From a network management point of view, the quality of the signal transmitted to the user is preferably represented by the actual FER or the observed FER (point E). The concept of PSNI provides an observed FER that is directly related to all STAs, despite the different performance penalty of each STA. This can be done by: 1) based on measurements on an internal demodulator parameter, 2) specifies the PSNI indicator value for the FER observed at the rate/demodulator/FEC combination point for the particular data, and 3) adjusts the measurements of the internal demodulator parameter to account for the actual FEC decoder loss that occurs for the downward transmission (downlink) from the measurement point. The measured signal quality already includes the front-end loss effect of the STA due to the use of a measurement point internal to the demodulator. The actual demodulator penalty is already included due to the PSNI indicator specifying the observed FER. The indicator is maintained valid by the FEC decoder that all STAs may use, since the demodulator's measurements are adjusted to account for the loss of the actual FEC demodulator.

Since PSNI is based on an internal demodulator parameter, it can be measured and reported on a frame-by-frame basis. BER or FER measurements at points C or E require many frames for accurate measurements. PSNI is therefore a practical, fast and useful indicator of observed signal quality.

The analog signal to noise ratio can be measured quickly at point a or point B, however they are not accurately correlated to the observed FER at point E since the loss of all the implementations or even the sum of the downward transmissions is not known.

Among these approaches, the inventive use of network managed PSNI is more efficient to perform, faster to measure, does not require STA to perform information, and is therefore an improvement over other discussions herein.

Fig. 2 shows the PSNI specified for the BER curve of the present invention. Fig. 3 shows an illustrative example point of PSNI amplification to a 43dB range.

Advantages of PSNI over RSSI include the following: the definition of PSNI, which is an eight-bit unsigned value (for DSSS PHYs) and is proportional to the received signal power, meets the RSSI requirement. PSNI can be reported in any data block called RSSI, enabling the PSNI indicator to be widely suited for intra frame quality measurements. PSNI MIB input values and reporting/publishing may further gain authorization in 802.11 so that the PSNI improvements may be applicable to higher layer frames.

The previous is a description of a PSNI indicator embodiment and network management method, the invention is designed to be applicable to all transmission modes including TDD, FDD, CDMA and other non-exceptional modes. The PSNI indicator described is also envisaged as well as a method with reasonable modifications. All such modifications and variations are considered to be within the purview and scope of the invention as claimed.

Claims (43)

1. A method for determining a perceived signal to noise indicator (PSNI) for management of a wireless network, comprising:

establishing the PSNI on a parameter obtained by measuring a signal obtained at a given location of a receiving device; and

a PSNI indication value is specified which is related to a Frame Error Rate (FER) obtained at the receiving device.

2. The method of claim 1, further comprising:

the PSNI parameter is used as a signal quality indicator for one of a Bit Error Rate (BER) and a Frame Error Rate (FER) to facilitate reconfiguration and management of the network to optimize the network performance.

3. The method of claim 1, further comprising:

the parameters are adjusted to produce a decoder penalty downstream of an FER decoder associated with the measurement point.

4. The method of claim 1, further comprising:

the parameters are adjusted to produce a downstream loss with respect to the measurement point.

5. The method of claim 4 wherein the parameters are obtained from a demodulator in the receiving device.

6. The method of claim 4 wherein the parameter is constant over the data rate.

7. The method of claim 4 wherein the parameter is one of a baseband phase jitter and a baseband error vector value.

8. The method of claim 4 wherein the parameter is a spreading code correction quality.

9. The method of claim 1, further comprising:

measurements are obtained at an output of a receive antenna of the receiving device.

10. The method of claim 1 wherein the parameter is one of a frequency tracking and a channel tracking stability.

11. The method of claim 1 wherein the step of specifying the PSNI value further comprises:

the PSNI indicator value is specified in relation to the FER obtained at least one particular data rate/demodulator/Forward Error Correction (FEC) combining point.

12. The method of claim 1 further comprising obtaining measurements at an internal point of a demodulator provided in said receiving device.

13. The method of claim 1 further comprising obtaining the measurement point at an output of a radio front end that is part of the receiving device.

14. The method of claim 1 further comprising obtaining measurements on an output of a demodulator provided in said receiving device.

15. The method of claim 1 wherein the PSNI is logarithmically proportional to a perceived signal to noise plus interference value.

16. A method for managing a wireless network, comprising the steps of:

determining a perceived signal to noise indication (PSNI) by measuring a signal by an Access Point (AP) at a receiving location, wherein a signal to noise plus interference value (S/N + I) is dependent on a parameter of the measured signal; and

the parameters are adjusted to compensate for downstream losses associated with the ap.

17. The method of claim 16 wherein the signal is measured at an AP of a demodulator at the receiving location.

18. The method of claim 16 wherein the signal is measured at an AP of a receiver at the receiving location.

19. The method of claim 16, further comprising:

converting the signal to a base frequency; and

an automatic gain control is provided to the baseband signal to maintain the baseband power constant.

20. The method of claim 19 wherein the PSNI is obtained after reception, analog to digital conversion, and demodulation of the signal physical layer (PHY) that is specific to and directly related to the observed frame error rate obtained from a Forward Error Correction (FEC) decoder.

21. The method of claim 20 wherein a Frame Error Rate (FER) is derived from a frame check Cyclic Redundancy Check (CRC).

22. An apparatus for managing a wireless network, comprising:

a determining means for determining a perceived signal to noise indicator (PSNI) by measuring a signal at an Access Point (AP), wherein the PSNI is dependent on a parameter of the signal obtained at the AP; and

an adjusting device for adjusting the parameter to generate a decoder downstream loss associated with the measurement point.

23. The apparatus of claim 22 further comprising means for correlating said PSNI value downstream of a Frame Error Rate (FER) acquisition with respect to said AP.

24. The apparatus of claim 23 wherein said means for correlating further comprises:

means for specifying the PSNI value in relation to the FER obtained at least one specific data rate/demodulator/Forward Error Correction (FEC) combining point.

25. The apparatus of claim 22 wherein the AP is an internal point of a demodulator provided in a receiver.

26. The apparatus of claim 25 wherein the AP is located at an output of a receive antenna for transmitting a receive signal to the receiver.

27. The apparatus of claim 25 wherein the AP is located at an output of a radio front end that is part of the receiver.

28. The apparatus of claim 25 wherein the AP is located at an output which is a demodulator of the receiver.

29. The apparatus of claim 22 wherein the PSNI is logarithmically proportional to a perceived signal to noise plus interference value.

30. An apparatus for managing a wireless network, comprising:

a determining means for determining a perceived signal to noise indicator (PSNI) by measuring a signal at an Access Point (AP) at a receiving location, wherein a signal to noise plus interference value (S/N + I) is a parameter of the signal received at a demodulator; and

a first adjusting device for adjusting the parameter to generate a downstream loss associated with the demodulator.

31. The apparatus of claim 30, further comprising:

a conversion device for converting the signal into a base frequency; and

a providing device for providing an automatic gain control to the baseband signal to maintain the baseband power constant.

32. The apparatus of claim 31 wherein the AP is downstream to a receiver, an analog-to-digital converter and a demodulator and is directly related to an observed frame error rate (fer) obtained from a Forward Error Correction (FEC) decoder.

33. The apparatus of claim 32 wherein a Frame Error Rate (FER) is obtained by the means for using a frame Cyclic Redundancy Check (CRC).

34. The apparatus of claim 30 wherein said means for adjusting further comprises:

a second adjusting device for adjusting the parameter to generate forward error correction decoder loss, which occurs downstream with respect to the demodulator.

35. The apparatus of claim 30, further comprising:

a Forward Error Correction (FEC) decoder;

a generating means for generating a repetition of a correct input bit input to the decoder;

a comparing means for comparing the generated input bits with a corresponding bit input to the decoder to determine a Bit Error Rate (BER); and

a response device for estimating a Frame Error Rate (FER) in response to the BER and the FEC decoder output.

36. The apparatus of claim 30 wherein the parameter is one of a baseband phase jitter and a baseband error vector value.

37. The apparatus of claim 30 wherein the parameter is a spreading code correction quality.

38. The apparatus of claim 30 wherein the parameter is one of a frequency tracking and a channel tracking stability.

39. The apparatus of claim 30, further comprising:

means for optimizing network performance using an obtained PSNI as a signal quality indicator for one of a Bit Error Rate (BER) and a Frame Error Rate (FER) to facilitate reconfiguration and management of the network.

40. The apparatus of claim 30 wherein the AP is an internal point of a demodulator provided in a receiver.

41. The apparatus of claim 30 wherein the AP is located at an output of a receive antenna for transmitting a receive signal to the receiving device.

42. The apparatus of claim 30 wherein the AP is located at an output of a radio front end that is part of the receiver.

43. The apparatus of claim 30 wherein the AP is located at an output of a demodulator for the receiving device.