Method of DTX detection in a wireless communication system
View Patent ↗There is provided a network node of a wireless communication network, such as a UMTS network. The network node is arranged to perform a method of detecting Signal Discontinuous Transmission on a channel in the wireless communication network. The method comprises the receiving of a signal on the channel and the processing of a current slot of the signal, the current slot comprising a number of pilot bits and non-pilot bits. A bit error rate, a signal to noise ratio and an amplitude modulus is calculated using the pilot bits and non-pilot bits. A decision is made about whether the signal indicates a discontinuous transmission on the channel using the signal to noise ratio, the bit error rate and the amplitude modulus.
1. A network node of a wireless communication network, the network node comprising:
a receiver arranged to receive a signal from a remote transmitter via a channel of the wireless communication system and to output a number of slot bits, the number of slot bits comprising a number of pilot bits and non-pilot bits;
a bit error rate calculator arranged to calculate a bit error rate using the pilot bits;
a signal to noise calculator arranged to calculate a signal to noise ratio using the pilot bits;
an amplitude modulus calculator arranged to calculate an amplitude modulus using the slot bits; and
a discontinuous transmission (DTX) detector arranged to make a decision about whether the signal indicates a discontinuous transmission on the channel using the signal to noise ratio, the bit error rate and the amplitude modulus.
2. A network node according to claim 1 , wherein the DTX detector is arranged to make the decision depending on a value of a multivariate decision function f(SNR, BER, AM) with SNR being the signal to noise ratio, BER being the bit error rate and AM being the amplitude modulus.
3. A network node according to claim 2 , wherein the multivariate decision function comprises a second order polynomial in AM.
4. A network node according to claim 2 , wherein the multivariate decision function comprises a second order polynomial in BER.
5. A network node according to claim 4 , wherein the multivariate decision function comprises a term being a polynomial in BER and AM divided by (1+SNR).
6. A network node according to claim 5 , wherein the decision function f is defined by:
f
=
c
0
+
c
1
A
M
+
c
2
A
M
2
+
c
3
B
E
R
2
+
c
4
+
c
5
A
M
+
c
6
B
E
R
1
+
S
N
R
with
AM being the amplitude modulus,
BER being the bit error rate,
SNR being the signal to noise ratio,
c 0 , c 1 , c 2 , c 3 , c 4 , c 5 , c 6 being coefficients.
7. A network node according to claim 6 , wherein values for the coefficients, c 0 , c 1 , c 2 , c 3 , c 4 , c 5 , c 6 , of the decision function are selected depending on the signal to noise ratio.
8. A network node according to claim 7 , wherein values for the coefficients, c 0 , c 1 , c 2 , c 3 , c 4 , c 5 , c 6 , of the decision function are selected depending on y a transmission status of a previous slot.
9. A network node according to claim 8 , wherein values for the coefficients, c 0 , c 1 , c 2 , c 3 , c 4 , c 5 , c 6 , of the decision function are selected depending on how many pilot bits are in the current slot.
10. A network node according to claim 9 , wherein values for the coefficients c 0 , c 1 , c 2 , c 3 , c 4 , c 5 , c 6 , of the decision function are selected depending on a speed of the transmitter transmitting the signal.
11. A network node according to claim 10 , wherein the coefficients c 1 , c 2 and c 5 are set to zero if the signal to noise ratio is below a predefined threshold.
12. A network node according to claim 11 , wherein the coefficients c 1 , c 2 and c 5 are set to zero if for the previous slot a discontinued transmission was detected.
13. A network node according to claim 1 , wherein the wireless network is a Universal Mobile Telecommunications System (UMTS) network using Wideband Code Division Multiple Access (WCDMA), and wherein the channel is an uplink (UL) dedicated physical control channel (DPCCH) channel.
14. A method of detecting Signal Discontinuous Transmission on a channel in a wireless communication network, the method comprising:
receiving, at a receiver, a signal on the channel;
processing a current slot of the signal, the current slot comprising a number of slot bits, the number of slot bits comprising a number of pilot bits;
calculating, at a bit error rate calculator, a bit error rate using the pilot bits;
calculating, at a signal to noise calculator, a signal to noise ratio using the pilot bits;
calculating, at an amplitude modulus calculator, an amplitude modulus using the slot bits; and
making, at a discontinuous transmission (DTX) detector, a decision about whether the signal indicates a discontinuous transmission on the channel using the signal to noise ratio, the bit error rate and the amplitude modulus.
15. A method according to claim 14 , wherein the decision is made depending on a value of a multivariate decision function f(SNR, BER, AM) with SNR being the signal to noise ratio, BER being the bit error rate and AM being the amplitude modulus.
16. A method according to claim 15 , wherein the multivariate decision function comprises a second order polynomial in AM.
17. A method according to claim 16 , wherein the multivariate decision function comprises a second order polynomial in BER.
18. A method according to claim 17 , wherein the multivariate decision function comprises a term being a polynomial in BER and AM divided by (1+SNR).
19. A method according to claim 18 , wherein the decision function f is defined by:
f
=
c
0
+
c
1
A
M
+
c
2
A
M
2
+
c
3
B
E
R
2
+
c
4
+
c
5
A
M
+
c
6
B
E
R
1
+
S
N
R
with
AM being the amplitude modulus,
BER being the bit error rate,
SNR being the signal to noise ratio,
c 0 , c 1 , c 2 , c 3 , c 4 , c 5 , c 6 being coefficients.
20. A non-transitory computer readable medium embodying a computer program comprising instructions for causing a programmable apparatus to perform a method, the method comprising:
receiving a signal on the channel;
processing a current slot of the signal, the current slot comprising a number of slot bits, the number of slot bits comprising a number of pilot bits;
calculating a bit error rate using the pilot bits;
calculating a signal to noise ratio using the pilot bits;
calculating an amplitude modulus using the slot bits; and
making a decision about whether the signal indicates a discontinuous transmission on the channel using the signal to noise ratio, the bit error rate and the amplitude modulus.