Title of Invention	METHOD FOR IMPROVING BIT ERROR RATE AT THE RECEIVER OF THE UMTS PHYSICAL LAYER THROUGH UTILIZATION OF THE REPEATED BITS ADDED DURING RATE MATCHING
Abstract	The invention proposes a method to for improving bit error rate at the receiver of the UMTS physical layer through utilization of the repeated bits added during rate matching. This method makes use of soft levels used by viterbi decoder for estimation of received data. The new method provides significant improvement in bit error rate performance compared to the conventional method as can be seen from the simulation results. The implementation of the scheme proposed in the invention does not require any additional hardware or algorithm and requires only a mechanism for making use of the repeated bits for estimation of the received data.

Title of Invention

METHOD FOR IMPROVING BIT ERROR RATE AT THE RECEIVER OF THE UMTS PHYSICAL LAYER THROUGH UTILIZATION OF THE REPEATED BITS ADDED DURING RATE MATCHING

Abstract

The invention proposes a method to for improving bit error rate at the receiver of the UMTS physical layer through utilization of the repeated bits added during rate matching. This method makes use of soft levels used by viterbi decoder for estimation of received data. The new method provides significant improvement in bit error rate performance compared to the conventional method as can be seen from the simulation results. The implementation of the scheme proposed in the invention does not require any additional hardware or algorithm and requires only a mechanism for making use of the repeated bits for estimation of the received data.

Full Text	FIELD OF TECHNOLOGY The present invention relates generally to the receiver of the UMTS mobile communication device. More particularly, this invention relates to a method and system of improving bit error rate at the receiver of the UMTS physical layer through the utilization of the repeated bits added during rate matching. PRESENT STATE OF ART Rate matching is used in the multiplexing operation of the physical layer of WCDMA (UMTS) to match the number of bits in the transport channels (TrCH) to the capacity of the physical channel. This is achieved either by puncturing some of the bits of the transport channel or by repetition of some of the bits of the transport channel in a pre-specified fashion. The number of bits on a transport channel can vary between different transmission time intervals (TTI). The duration of each TTI may be 10, 20, 40 or 80 ms ([1]) when the number of bits between different transmission time intervals is changed; bits are repeated or punctured to ensure that the total bit rate after TrCH multiplexing is same as the total channel bit rate of the allocated dedicated physical channels. The number of bits, which can be sent on a single frame of any physical channel, is fixed (and is determined by the data rate of the physical channel or the spreading factor). If the number of bits in the transport channel is such that the bits do not fit exactly into the frame of physical channel, then either puncturing or repetition is done. If the number of bits is lesser, then some of the bits are repeated in all the transport channels proportionately. Similarly if the number of bits is more, then some of the bits are punctured (removed) from all the transport channels proportionately. Structure of Related Art Data bits from higher layers pass through various data processing steps in the physical layer (viz), CRC attachment, Transport block concatenation, channel coding, Rate matching, Insertion of the Discontinuous transmission (DTX) bits, Interleaving, Transport channel multiplexing, Physical channel segmentation and mapping (Figure 1). While Figure 1 pertains to downlink transmission, the uplink transmission is similar in approach ([2]). Operation of Related Art At the receiver end; the de-ratematching block generates the same pattern of rate matching as the ratematching block and will ignore occurrence of repeated bits. These bits are received in the form of soft levels, which are used by viterbi decoder to perform decoding and take decision on each bit. LIMITATIONS In the existing art, the repeated bits are ignored while performing de-rate matching at the receiver end. And the punctured bits are given a soft value, which corresponds to 50% probability of being 1 or 0. Thus puncturing will result in an amount of degradation in error performance. This method does not utilize the repeated bits. During de-ratematching operation, repeated bits are simply ignored at the receiver side. While puncturing is degrading the error performance to some extent, repetition does not achieve any gain in error performance either OBJECTS OF THE INVENTION The primary object of this invention is to invent a method of addition for improving the bit error rate at the receiver of the UMTS physical layer through utilization of repeated bits during rate matching. It is another object of this invention to improve the Block Error Rate (BLER) performance of the UMTS receiver by using the information of the repeated bits included as a result of rate matching. It is another object of the invention to invent a method wherein the average value of the soft levels of the repeated bits at the receiver gives a better estimation of the soft level of the bit transmitted, which is used at the receiver for the soft decoding (for example, viterbi decoding). SUMMARY OF THE INVENTION The present invention relates to a method of improving the bit error rate (or block error rate) at the receiver of the WCDMA (UMTS) physical channel, by using the repeated bits added during the rate matching operation instead of ignoring them. The scheme proposed in the invention achieves a better estimation of soft decision level using the repeated bits, which in turn gives additional gain in the viterbi decoding. Instead of ignoring repeated bits at the receiver side, their average value is taken for the estimation of the soft decision level. This invention results in a significant improvement in the BLER at the receiver. Accordingly, the present invention relates to a method of improving the bit error rate of the receiver of a Universal Mobile Telecommunication System having transmitter and a receiver wherein the said method comprising the steps of: (a) generating random pattern of bits Os and 1s by data bit generator; (b) coding the generated incoming bits at 1/2 or 1/3 rate by the convolutional coder; (c) repeating the channel coded bits in a definite pattern by a rate matching block; (d) providing logical levels to the incoming bits by a discrete memoryless channel; (e) taking the average value of the redundant bits by a de-ratematching module for the estimation of the soft decision level; (f) passing de-ratematched bits through viterbi soft decision decoder for soft decision decoding; and (g) computing BLER on of the received block with reference to the transmitted block, wherein improving the bit error rate at the receiver is done through utilization of repeated bits during rate matching. The other objects, features and advantages of the present invention will be apparent from the accompanying drawings and the detailed description as follows. BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS Figure 1 shows the bit level data processing chain of the downlink of UMTS based 3G system. Figure 2 shows a block diagram of the present invention. Figure 3 illustrates the BLER performance for Channel 1. Figure 4 illustrates the BLER performance for Channel 2 DETAILED DESCRIPTION OF THE INVENTION A preferred embodiment of the present invention will now be explained with reference to the accompanying drawings. It should be understood however that the disclosed embodiment is merely exemplary of the invention, which may be embodied in various forms. The following description and drawings are not to be construed as limiting the invention and numerous specific details are described to provide a thorough understanding of the present invention, as the basis for the claims and as a basis for teaching one skilled in the art how to make and/or use the invention. However in certain instances, well-known or conventional details are not described in order not to unnecessarily obscure the present invention in detail. The 3rd Generation Partnership Project (3GPP) is a collaboration agreement that was established in December 1998. The collaboration agreement brings together a number of telecommunications standards bodies which are known as "Organizational Partners". The current Organizational Partners are ARIB, CCSA, ETSI, ATIS, TTA, and TTC. The establishment of 3GPP was formalized in December 1998 by the signing of the 'The 3rd Generation Partnership Project Agreement". The original scope of 3GPP was to produce globally applicable Technical Specifications and Technical Reports for a 3rd Generation Mobile System based on evolved GSM core networks and the radio access technologies that they support (i.e., Universal Terrestrial Radio Access (UTRA) both Frequency Division Duplex (FDD) and Time Division Duplex (TDD) modes). The scope was subsequently amended to include the maintenance and development of the Global System for Mobile communication (GSM) Technical Specifications and Technical Reports including evolved radio access technologies (e.g. General Packet Radio Service (GPRS) and Enhanced Data rates for GSM Evolution (EDGE)). In the process of "channel coding and multiplexing" in UMTS physical layer, as shown in Figure 1, rate matching is done to fit the number of bits in transport channels to the physical channel ([2]). Rate matching block in the transmitter will either repeat or puncture some number of bits based on the size of the transport channel. The pattern in which rate matching block repeats or puncture the bits is as given in 3GPP specification. To validate this concept, as an example, an equivalent model for simulation as shown in figure 2 is presented. Only those modules, which are relevant to the present invention, are used for simulation instead of full Transmitter - Receiver chain. Data bit generator generates random pattern of bits Os and 1s. Bits, thus generated, pass through the convolutional coder block, which can code the incoming bits at 1/2 or 1/3 rate. Channel coded bits are passed through a rate matching block where bits are repeated in a defined fashion. In 3GPP standards, rate matching provides a wide variety of data repetition/puncturing patterns depending on the number of incoming data bits, number of transport channel to be multiplexed together in a single CCTRCH, spreading factor of the physical channel on which rate matched bits are mapped, number of the physical channel used, etc. Here attention is focused on the repeated bits only. Simplified bit repetition scenarios are simulated and the cases where x% of the channel coded bits are repeated, where 0 Rate matched bits are passed though a discrete memoryless channel (DMC) which, depending on the transition probability matrix, provides logical levels to the incoming bits. Output of the DMC is Soft level bits. Soft level bits are passed through the de-ratematching module, which does the reverse operation of the rate matching and removes redundant bits in the existing art. In the proposed scheme, redundant bits are not removed. Instead, their average value is taken for estimation of the soft decision level. Method of averaging works out well and it is explained as below: Suppose bit X1 is transmitted when the channel condition is poor, estimations of received bit Y1 at the receiver when X1 is transmitted will be poor. Transmission of repeated bit X1 gives a better estimation of the received bit y2. Moreover, all the repeated bits may experience different channel condition since the channel is fast fading. Taking average of all the estimated bits gives better estimation of the transmitted bit X1 and hence improved performance in bit error rate at the receiver. Following algorithm is used to validate this concept. While (Incoming Bits) { if (Repeated Bit) { Output Soft Level = Average (Soft Level of the input bits + soft level of the repeated bits) } else { OutputSoft Level = Input Soft Level } } De-ratematched bits are passed through viterbi soft decision decoder. Decoder performance varies depending upon the estimation of the soft decision levels. As in any channel coding scheme, the gain in our simulations also depends upon channel conditions. Simulation analyses have been done for two types of channels as shown below in the simulation parameters. Simulation exercise and results: Data Block size in 3G varies based on the application type. Data block size can be as high as 640 bits. However, data block size of 150 bits is the most frequently used. Therefore data block size of 150 bits is chosen for simulation. Performance of our proposed scheme depends on the percentage of repeated bits and not on the block size. Repeated bits in the range of from 0% to 30% are applied in the simulation, as this is the typical range of repetition in 3G systems. Following simulation parameters are used to validate this concept. Data Block Size: 150 bits Channel coding scheme: Convolution coding, Rate % [as defined in 3gpp ref document 25.212] Rate matching: Simulation is done for x% of repeated bits, where 0 Channel decoding scheme: Viterbi Soft decision decoder Discrete Memoryless Channel: Binary input, octal output channel Following transition probability matrices are used for simulation: Table 2: Probability transition matrix for DMC, channel 2 From the graphs as illustrated in figures 3 and 4, it is clear that improvement (in terms of BLER) is dependent on the percentage of repetition. At 30% repetition, BLER improvement of approx 60 % is observed and for the case of 0% repetition, the old as well as the new approach behaves similarly as expected. Structure of the Invention In the scheme proposed in the invention, the repeated bits are not ignored and the average of their soft levels is used by viterbi decoder for estimation. The block error rate of the received bit stream involves the following functions: • Random data bits generation (0s and 1s) • Convolutional coding of the incoming data stream. • Rate matching of the input bits with a given repetition probability • Application of the discrete memory less channel in the path of data bits • De-ratematching operation with the repeated bits being averaged for the better estimation of the soft level. • Soft decision decoding of the De-ratematched bits using Viterbi decoding algorithm • BLER computation of the received block with reference to the transmitted block. As shown in Figure 3 and Figure 4, BLER gain from the proposed scheme is significantly better. Old approach refers to the standard method of De-rate matching; while Modified approach refers to the proposed De-rate matching method. As can be seen from Figs. 3 and 4, there is a substantial improvement in the BLER performance for high bit repetition case. As the bit repetition probability approaches 0 (meaning that there is no bit being repeated), both the schemes have similar BLER performance. No additional hardware or algorithm is needed for this invention, except a mechanism for not ignoring the repeated bits and taking the average of their soft levels. Instead of taking simple average of the repeated bits, their weighted average can be taken. Repeated bits can be weighted based on channel estimation being done on Common Pilot Channel (CPICH). This scheme could be useful for the case when repeated bits are distributed in the frame and channel is fast changing. It will also be obvious to those skilled in the art that other control methods and apparatuses can be derived from the combinations of the various methods and apparatuses of the present invention as taught by the description and the accompanying drawings and these shall also be considered within the scope of the present invention. Further, description of such combinations and variations is therefore omitted above. It should also be noted that the host for storing the applications include but not limited to a computer, mobile communication device, printer or a multi function device. Although the present invention has been fully described in connection with the preferred embodiments thereof with reference to the accompanying drawings, it is to be noted that various changes and modifications are possible and are apparent to those skilled in the art. Such changes and modifications are to be understood as included within the scope of the present invention as defined by the appended claims unless they depart therefrom. GLOSSARY OF THE TERMS AND THEIR DEFINITIONS 3G: Third Generation BLER: Block Error Rate CCTRCH: Coded composite transport Channel as discussed in ref [2] CPICH: Common Pilot Channel CRC: Cyclic redundancy Check as discussed in ref [2] DMC: Discrete Memoryless channel DTX: Discontinuous Transmission TrCh: Transport Channel as discussed in ref. [1] TTI: Transmission time Interval as discussed in Ref. [1] TrBk: Transport Block as discussed in ref [1] UMTS: Universal mobile telecommunication system. WCDMA: Wideband Code division multiple access REFERENCES [1] 3GPP TS 25.302: "Services Provided by the Physical Layer". [2] 3GPP TS 25.212: "Multiplexing and channel coding (FDD)". WE CLAIM 1. A method of improving the bit error rate of the UMTS physical layer comprising the steps of: (a) generating random pattern of bits Os and is by data bit generator; (b) coding the generated incoming bits at 1/2 or 1/3 rate by the convolutional coder; (c) repeating the channel coded bits in a definite pattern by a rate matching block; (d) providing logical levels to the incoming bits by a discrete memoryless channel; (e) taking the average value of the redundant bits by a de-ratematching module for the estimation of the soft decision level; (f) passing de-ratematched bits through viterbi soft decision decoder for soft decision decoding; and (g) computing BLER on of the received block with reference to the transmitted block, wherein improving the bit error rate at the receiver is done through utilization of repeated bits during rate matching. 2. A method as claimed in claim 1 wherein Output of the DMC is Soft level bits. 3. A method as claimed in claim 1 wherein a wide variety of data repetition patterns depends on the number of incoming data bits, number of transport channel to be multiplexed together in a single CCTRCH, spreading factor of the physical channel on which rate matched bits are mapped, number of the physical channel used. 4. A method as claimed in claim 1 wherein if repeated bits are distributed in the frame and channel is fast changing weighted average based on channel estimation being done on Common Pilot Channel (CPICH) of the repeated bits is taken.

Full Text

FIELD OF TECHNOLOGY
The present invention relates generally to the receiver of the UMTS mobile communication device. More particularly, this invention relates to a method and system of improving bit error rate at the receiver of the UMTS physical layer through the utilization of the repeated bits added during rate matching.
PRESENT STATE OF ART
Rate matching is used in the multiplexing operation of the physical layer of WCDMA (UMTS) to match the number of bits in the transport channels (TrCH) to the capacity of the physical channel. This is achieved either by puncturing some of the bits of the transport channel or by repetition of some of the bits of the transport channel in a pre-specified fashion.
The number of bits on a transport channel can vary between different transmission time intervals (TTI). The duration of each TTI may be 10, 20, 40 or 80 ms ([1]) when the number of bits between different transmission time intervals is changed; bits are repeated or punctured to ensure that the total bit rate after TrCH multiplexing is same as the total channel bit rate of the allocated dedicated physical channels.
The number of bits, which can be sent on a single frame of any physical channel, is fixed (and is determined by the data rate of the physical channel or the spreading factor). If the number of bits in the transport channel is such that the bits do not fit exactly into the frame of physical channel, then either puncturing or repetition is done. If the number of bits is lesser, then some of the bits are repeated in all the transport channels proportionately. Similarly if the number of bits is more, then some of the bits are punctured (removed) from all the transport channels proportionately.

Structure of Related Art
Data bits from higher layers pass through various data processing steps in the physical layer (viz), CRC attachment, Transport block concatenation, channel coding, Rate matching, Insertion of the Discontinuous transmission (DTX) bits, Interleaving, Transport channel multiplexing, Physical channel segmentation and mapping (Figure 1). While Figure 1 pertains to downlink transmission, the uplink transmission is similar in approach ([2]).
Operation of Related Art
At the receiver end; the de-ratematching block generates the same pattern of rate matching as the ratematching block and will ignore occurrence of repeated bits. These bits are received in the form of soft levels, which are used by viterbi decoder to perform decoding and take decision on each bit.
LIMITATIONS
In the existing art, the repeated bits are ignored while performing de-rate matching at the receiver end. And the punctured bits are given a soft value, which corresponds to 50% probability of being 1 or 0. Thus puncturing will result in an amount of degradation in error performance.
This method does not utilize the repeated bits. During de-ratematching operation, repeated bits are simply ignored at the receiver side. While puncturing is degrading the error performance to some extent, repetition does not achieve any gain in error performance either
OBJECTS OF THE INVENTION
The primary object of this invention is to invent a method of addition for improving the bit error rate at the receiver of the UMTS physical layer through utilization of repeated bits during rate matching.

It is another object of this invention to improve the Block Error Rate (BLER) performance of the UMTS receiver by using the information of the repeated bits included as a result of rate matching.
It is another object of the invention to invent a method wherein the average value of the soft levels of the repeated bits at the receiver gives a better estimation of the soft level of the bit transmitted, which is used at the receiver for the soft decoding (for example, viterbi decoding).
SUMMARY OF THE INVENTION
The present invention relates to a method of improving the bit error rate (or block error rate) at the receiver of the WCDMA (UMTS) physical channel, by using the repeated bits added during the rate matching operation instead of ignoring them.
The scheme proposed in the invention achieves a better estimation of soft decision level using the repeated bits, which in turn gives additional gain in the viterbi decoding. Instead of ignoring repeated bits at the receiver side, their average value is taken for the estimation of the soft decision level. This invention results in a significant improvement in the BLER at the receiver.
Accordingly, the present invention relates to a method of improving the bit error rate of the receiver of a Universal Mobile Telecommunication System having transmitter and a receiver wherein the said method comprising the steps of:
(a) generating random pattern of bits Os and 1s by data bit generator;
(b) coding the generated incoming bits at 1/2 or 1/3 rate by the convolutional coder;
(c) repeating the channel coded bits in a definite pattern by a rate matching block;
(d) providing logical levels to the incoming bits by a discrete memoryless channel;

(e) taking the average value of the redundant bits by a de-ratematching module for the estimation of the soft decision level;
(f) passing de-ratematched bits through viterbi soft decision decoder for soft decision decoding; and
(g) computing BLER on of the received block with reference to the transmitted block,
wherein improving the bit error rate at the receiver is done through utilization of repeated bits during rate matching.
The other objects, features and advantages of the present invention will be apparent from the accompanying drawings and the detailed description as follows.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Figure 1 shows the bit level data processing chain of the downlink of UMTS based 3G system.
Figure 2 shows a block diagram of the present invention.
Figure 3 illustrates the BLER performance for Channel 1.
Figure 4 illustrates the BLER performance for Channel 2
DETAILED DESCRIPTION OF THE INVENTION
A preferred embodiment of the present invention will now be explained with reference to the accompanying drawings. It should be understood however that the disclosed embodiment is merely exemplary of the invention, which may be embodied in various forms. The following description and drawings are not to be construed as limiting the invention and numerous specific details are described to provide a thorough understanding of the present invention, as the basis for the

claims and as a basis for teaching one skilled in the art how to make and/or use the invention. However in certain instances, well-known or conventional details are not described in order not to unnecessarily obscure the present invention in detail.
The 3rd Generation Partnership Project (3GPP) is a collaboration agreement that was established in December 1998. The collaboration agreement brings together a number of telecommunications standards bodies which are known as "Organizational Partners". The current Organizational Partners are ARIB, CCSA, ETSI, ATIS, TTA, and TTC.
The establishment of 3GPP was formalized in December 1998 by the signing of the 'The 3rd Generation Partnership Project Agreement".
The original scope of 3GPP was to produce globally applicable Technical Specifications and Technical Reports for a 3rd Generation Mobile System based on evolved GSM core networks and the radio access technologies that they support (i.e., Universal Terrestrial Radio Access (UTRA) both Frequency Division Duplex (FDD) and Time Division Duplex (TDD) modes). The scope was subsequently amended to include the maintenance and development of the Global System for Mobile communication (GSM) Technical Specifications and Technical Reports including evolved radio access technologies (e.g. General Packet Radio Service (GPRS) and Enhanced Data rates for GSM Evolution (EDGE)).
In the process of "channel coding and multiplexing" in UMTS physical layer, as shown in Figure 1, rate matching is done to fit the number of bits in transport channels to the physical channel ([2]).
Rate matching block in the transmitter will either repeat or puncture some number of bits based on the size of the transport channel. The pattern in which rate matching block repeats or puncture the bits is as given in 3GPP specification.

To validate this concept, as an example, an equivalent model for simulation as shown in figure 2 is presented. Only those modules, which are relevant to the present invention, are used for simulation instead of full Transmitter - Receiver chain.
Data bit generator generates random pattern of bits Os and 1s. Bits, thus generated, pass through the convolutional coder block, which can code the incoming bits at 1/2 or 1/3 rate. Channel coded bits are passed through a rate matching block where bits are repeated in a defined fashion. In 3GPP standards, rate matching provides a wide variety of data repetition/puncturing patterns depending on the number of incoming data bits, number of transport channel to be multiplexed together in a single CCTRCH, spreading factor of the physical channel on which rate matched bits are mapped, number of the physical channel used, etc. Here attention is focused on the repeated bits only. Simplified bit repetition scenarios are simulated and the cases where x% of the channel coded bits are repeated, where 0 Rate matched bits are passed though a discrete memoryless channel (DMC) which, depending on the transition probability matrix, provides logical levels to the incoming bits. Output of the DMC is Soft level bits. Soft level bits are passed through the de-ratematching module, which does the reverse operation of the rate matching and removes redundant bits in the existing art.
In the proposed scheme, redundant bits are not removed. Instead, their average value is taken for estimation of the soft decision level.
Method of averaging works out well and it is explained as below: Suppose bit X1 is transmitted when the channel condition is poor, estimations of received bit Y1 at the receiver when X1 is transmitted will be poor.

Transmission of repeated bit X1 gives a better estimation of the received bit y2. Moreover, all the repeated bits may experience different channel condition since the channel is fast fading. Taking average of all the estimated bits gives better estimation of the transmitted bit X1 and hence improved performance in bit error rate at the receiver.
Following algorithm is used to validate this concept.
While (Incoming Bits)
{ if (Repeated Bit)
{ Output Soft Level = Average (Soft Level of the input bits + soft level of the
repeated bits)
} else
{ OutputSoft Level = Input Soft Level
} }
De-ratematched bits are passed through viterbi soft decision decoder. Decoder performance varies depending upon the estimation of the soft decision levels. As in any channel coding scheme, the gain in our simulations also depends upon channel conditions. Simulation analyses have been done for two types of channels as shown below in the simulation parameters.
Simulation exercise and results:
Data Block size in 3G varies based on the application type. Data block size can be as high as 640 bits. However, data block size of 150 bits is the most frequently used. Therefore data block size of 150 bits is chosen for simulation.

Performance of our proposed scheme depends on the percentage of repeated bits and not on the block size. Repeated bits in the range of from 0% to 30% are applied in the simulation, as this is the typical range of repetition in 3G systems.
Following simulation parameters are used to validate this concept.
Data Block Size: 150 bits
Channel coding scheme: Convolution coding, Rate % [as defined in
3gpp ref document 25.212]
Rate matching: Simulation is done for x% of repeated bits,
where 0 Channel decoding scheme: Viterbi Soft decision decoder
Discrete Memoryless Channel: Binary input, octal output channel
Following transition probability matrices are used for simulation:

Table 2: Probability transition matrix for DMC, channel 2
From the graphs as illustrated in figures 3 and 4, it is clear that improvement (in terms of BLER) is dependent on the percentage of repetition. At 30% repetition, BLER improvement of approx 60 % is observed and for the case of 0% repetition, the old as well as the new approach behaves similarly as expected.
Structure of the Invention
In the scheme proposed in the invention, the repeated bits are not ignored and
the average of their soft levels is used by viterbi decoder for estimation.
The block error rate of the received bit stream involves the following functions:
• Random data bits generation (0s and 1s)
• Convolutional coding of the incoming data stream.
• Rate matching of the input bits with a given repetition probability
• Application of the discrete memory less channel in the path of data
bits
• De-ratematching operation with the repeated bits being averaged
for the better estimation of the soft level.
• Soft decision decoding of the De-ratematched bits using Viterbi
decoding algorithm
• BLER computation of the received block with reference to the
transmitted block.
As shown in Figure 3 and Figure 4, BLER gain from the proposed scheme is significantly better. Old approach refers to the standard method of De-rate matching; while Modified approach refers to the proposed De-rate matching method. As can be seen from Figs. 3 and 4, there is a substantial improvement in the BLER performance for high bit repetition case. As the bit repetition probability approaches 0 (meaning that there is no bit being repeated), both the schemes have similar BLER performance. No additional hardware or algorithm is

needed for this invention, except a mechanism for not ignoring the repeated bits and taking the average of their soft levels.
Instead of taking simple average of the repeated bits, their weighted average can be taken. Repeated bits can be weighted based on channel estimation being done on Common Pilot Channel (CPICH). This scheme could be useful for the case when repeated bits are distributed in the frame and channel is fast changing.
It will also be obvious to those skilled in the art that other control methods and apparatuses can be derived from the combinations of the various methods and apparatuses of the present invention as taught by the description and the accompanying drawings and these shall also be considered within the scope of the present invention. Further, description of such combinations and variations is therefore omitted above. It should also be noted that the host for storing the applications include but not limited to a computer, mobile communication device, printer or a multi function device.
Although the present invention has been fully described in connection with the preferred embodiments thereof with reference to the accompanying drawings, it is to be noted that various changes and modifications are possible and are apparent to those skilled in the art. Such changes and modifications are to be understood as included within the scope of the present invention as defined by the appended claims unless they depart therefrom.

GLOSSARY OF THE TERMS AND THEIR DEFINITIONS
3G: Third Generation
BLER: Block Error Rate
CCTRCH: Coded composite transport Channel as discussed in ref [2]
CPICH: Common Pilot Channel
CRC: Cyclic redundancy Check as discussed in ref [2]
DMC: Discrete Memoryless channel
DTX: Discontinuous Transmission
TrCh: Transport Channel as discussed in ref. [1]
TTI: Transmission time Interval as discussed in Ref. [1]
TrBk: Transport Block as discussed in ref [1]
UMTS: Universal mobile telecommunication system.
WCDMA: Wideband Code division multiple access

REFERENCES
[1] 3GPP TS 25.302: "Services Provided by the Physical Layer". [2] 3GPP TS 25.212: "Multiplexing and channel coding (FDD)".

WE CLAIM
1. A method of improving the bit error rate of the UMTS physical layer comprising
the steps of:
(a) generating random pattern of bits Os and is by data bit generator;
(b) coding the generated incoming bits at 1/2 or 1/3 rate by the convolutional coder;
(c) repeating the channel coded bits in a definite pattern by a rate matching block;
(d) providing logical levels to the incoming bits by a discrete memoryless channel;
(e) taking the average value of the redundant bits by a de-ratematching module for the estimation of the soft decision level;
(f) passing de-ratematched bits through viterbi soft decision decoder for soft decision decoding; and
(g) computing BLER on of the received block with reference to the transmitted block,
wherein improving the bit error rate at the receiver is done through utilization of repeated bits during rate matching.
2. A method as claimed in claim 1 wherein Output of the DMC is Soft level bits.
3. A method as claimed in claim 1 wherein a wide variety of data repetition patterns depends on the number of incoming data bits, number of transport channel to be multiplexed together in a single CCTRCH, spreading factor of the physical channel on which rate matched bits are mapped, number of the physical channel used.
4. A method as claimed in claim 1 wherein if repeated bits are distributed in the frame and channel is fast changing weighted average based on channel estimation being done on Common Pilot Channel (CPICH) of the repeated bits is taken.

Documents:

1074-che-2003 abstract granted.pdf

1074-che-2003 claims granted.pdf

1074-che-2003 description (complete) granted.pdf

1074-che-2003 drawings granted.pdf

1074-che-2003-abstract.pdf

1074-che-2003-claims.pdf

1074-che-2003-correspondnece-others.pdf

1074-che-2003-correspondnece-po.pdf

1074-che-2003-description(complete).pdf

1074-che-2003-drawings.pdf

1074-che-2003-form 1.pdf

1074-che-2003-form 19.pdf

1074-che-2003-form 26.pdf

« Previous Patent

Next Patent »

Patent Number

225810

Indian Patent Application Number

1074/CHE/2003

PG Journal Number

02/2009

Publication Date

09-Jan-2009

Grant Date

01-Dec-2008

Date of Filing

31-Dec-2003

Name of Patentee

SAMSUNG INDIA SOFTWARE OPERATIONS PRIVATE LIMITED

Applicant Address

BAGMANE LAKEVIEW, BLOCK 'B', NO. 66/1, BAGMANE TECH PARK, C V RAMAN NAGAR, BYRASANDRA, BANGALORE 560 093,

Inventors:

#	Inventor's Name	Inventor's Address
1	KARMANI, GULSHAN	BAGMANE LAKEVIEW, BLOCK 'B', NO. 66/1, BAGMANE TECH PARK, C V RAMAN NAGAR, BYRASANDRA, BANGALORE 560 093,
2	SHARMA, GAURAV	BAGMANE LAKEVIEW, BLOCK 'B', NO. 66/1, BAGMANE TECH PARK, C V RAMAN NAGAR, BYRASANDRA, BANGALORE 560 093,

PCT International Classification Number

G06F011/00

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA