Detecting interference in a wireless communication system

• US 8,260,210 B2
• Filed: 02/01/2010
• Issued: 09/04/2012
• Est. Priority Date: 01/30/2009
• Status: Expired due to Fees

• Current Assignee: Vodafone Group PLC
• Original Assignee: Vodafone Group PLC
• Inventors: Esteve Asensio, Guillermo, Rubio Andres, Francisco Javier, Murillo Fuentes, Juan Jose, Martinez Olmos, Pablo
• Primary Examiner(s): GONZALES, APRIL GUZMAN
• Application Number:
  US12/698,050
• Publication Number:
  US 20100279624A1
• Time in Patent Office: 946 Days
• Field of Search: 455/423, 455/435.2, 455/456.1, 455/424, 455/434, 455/67.11, 455/67.13, 379/32.01, 379/1.01, 365/158
• US Class Current: 455/67.11
• CPC Class Codes: H04B 17/26 using historical data, averaging values or statistics
• CPC Class Codes: H04B 17/318 Received signal strength
• CPC Class Codes: H04B 17/345 Interference values signal-to-interference ratio [SIR] or carrier-to-interference ratio [CIR] H04B17/336

Abstract

Method to determine the existence of interferences in a wireless communication link based on comparing the power received at both links of radio channel and the propagation losses calculated from both power and quality measurements, comprising:

• • (i) gathering values RXLEV_UL and RXLEV_DL;
  • (ii) using said values to estimate the receiver power level in the base station;
  • (iii) statistical analysis of the two different estimations obtained (P_{RXLEV UL}ⁱ, and {tilde over (P)}{tilde over (P_ULⁱ)}) for every connection i in the radio link;
  • (iv) comparing the estimations (P_{RXLEV UL}ⁱ and {tilde over (P)}{tilde over (P_ULⁱ)}) of the uplink received signals strength with the quality parameters RXQUAL_UL and RXQUAL_DL;
  • (v) computing the behavior of the computed values p_sⁱ and R_snri,
  • (vi) analyzing the results to detect:
    • (a) steady-state abnormalities;
    • (b) unbalanced interferences;
    • (c) malfunctioning of the power control; and
    • (d) inadequate radio planning.

Claims

1. A method to determine the existence of interferences in a wireless communication link based on comparing the power received at both links of radio channel and the propagation losses calculated from both power and quality measurements, the method comprising the following steps:

(i) a first step of gathering, for each established connection, the values RXLEV_UL and RXLEV_DL;

(ii) a second step of using independently the values RXLEV_UL and RXLEV_DL to estimate the receiver power level in the base station and, therefore, obtaining two different estimations for the uplink received power per user, wherein said two different estimations are denoted as;

P<sub>RXLEV—

UL</sub>ⁱ which is the estimation of the received power strength in the UL that is obtained solely from the measurements of the UL received signal strength; and

{tilde over (P)}_ULⁱ it which is the estimation of the received power strength in the DL updated with the difference in the transmitted power between UL and DL that is obtained only from the measurements of the DL received signal strength;

(iii) a third step of statistical analysis of the two different estimations obtained in the second step (P<sub>RXLEV—

UL</sub>ⁱ and {tilde over (P)}_ULⁱ) for every connection i in the radio link;

(iv) a fourth step of comparing the estimations (P<sub>RXLEV—

UL</sub>ⁱ and {tilde over (P)}_ULⁱ) of the uplink received signals strength made at the second step with the quality parameters RXQUAL_UL and RXQUAL_DL;

(v) a fifth step of computing the behaviour of the values p_sⁱ and R_snri computed in the fourth step, said values being defined as;

p_sⁱ which is the sequence of the estimation of the standard deviation of the estimations of the received power levels in the UL per connection, and represents the difference between the two estimations respect to the average value; and

R_snri which is the comparison ratio between the signal noise interference ratio for uplink and downlink;

(vi) a sixth step of analyzing the results of the fifth step configured to detect, at least, the following points;

(a) steady-state abnormalities if the power versus quality points gather around a point with a high standard deviation, or a point with different qualities;

(b) unbalanced interferences, wherein the distributions of the points in the high standard deviation versus R_snri representation explain the presence of unbalanced interferences;

(c) malfunctioning of the power control;

a large concentration of points out of the line R_snri=1 also may be a result of a poor performance of the power control method; and

(d) inadequate radio planning;

a recurrent unbalanced and time variant interference caused by other radio links within the same system.

2. The method according to claim 1 wherein the second step further comprises a first sub-step of providing a direct estimation due to the parameter RXLEV_UL, and a second sub-step of calculating the propagation losses in the DL and then assimilating them to the propagation losses in the UL due to the parameter RXLEV_DL.

3. The method according to claim 2 wherein the first sub-step of the second step further comprises a UL power signal estimation based on RXLEV_UL value, starting from the value RXLEV_UL(i), which refers to the power signal measurement by the base station for the i-th connection of a particular radio link.

4. The method according to claim 2 wherein the second sub-step comprises a DL power estimation based on the RXLEV_DL parameter and equivalent UL received power and, therefore it is analyzed the power level that will be received at the mobile device;

the signal strength received by the connection i is then used, this is the parameter RXLEV_DL(i), and the transmission power at both ends of the radio link to make the desired estimation;

at the base station there is information of the power transmitted in each connection in addition to the value of the received signal strength because the power control of the mobile is performed by the base station;

the following values are available for the connection number i of a radio channel;

P<sub>RXLEV—

DL</sub>ⁱ(dBm);

DL measured signal strength

P_MS(i)^BTS(dBm);

DL transmitted signal strength

P_BTS^MS(i)(dBm);

UL transmitted signal strength

and it further comprises the following steps;

starting from the DL signal levels for transmission and reception, we will estimate the propagation losses for each user,

L_MS(i)^BTS(dB)=P_MS(i)^BTS(dBm)−

P<sub>RXLEV—

DL</sub>ⁱ 

 

(7)

then it is assumed the reciprocity of the radio channel using the losses estimated in the DL, equation (1), to estimate the propagation losses in the UL

L_BTS^MS(i)(dB)=L_MS(i)^BTS(dB) 

 

(8)

finally it is estimated the equivalent received signal strength using the previous data, obtaining a value relative to the UL from data of the DL, defining this value as {tilde over (P)}_ULⁱ for connection number i as follows;

{tilde over (P)}_ULⁱ(dBm)=P_BTS^MS(i)(dBm)−

L_BTS^MS(i))(dB) 

 

(9)

wherein said equation (3) is the average UL signal strength received in the case that the propagation conditions of the UL were identical to the DL.

5. The method according to claim 1 wherein the third step of statistical analysis uses the average sequence of P_RXLEV—

_ULⁱ and {tilde over (P)}_ULⁱ and their standard deviation, and wherein this values as defined as;

the sequence of the estimation of the average received power level in the UL per connection, that is the arithmetic average of the two estimations made for the UL received power level at connection number i;

6. The method according to claim 1 wherein the fourth step further comprises, at least, a first sub-step of generation an estimation of the Signal-to-Noise and Interference ratio (SNIR) from the quality parameters;

and a second sub-step of analyzing the previous results defining a comparison parameter R_snri the Signal-to-Noise Interference ratio for uplink and downlink providing information about the noise and the interference on each path.