WO2013006028A1

WO2013006028A1 - A method to improve signal quality in a communication network

Info

Publication number: WO2013006028A1
Application number: PCT/MY2012/000134
Authority: WO
Inventors: Wahidah Hashim; Nordin Ramli; Hafizal Mohamad
Original assignee: Mimos Berhad
Priority date: 2011-07-01
Filing date: 2012-06-22
Publication date: 2013-01-10

Abstract

The present invention relates to a method to improve signal quality in a communication network, more particularly for error data detec¬ tion and correction. One of the advantages of the method to improve signal quality in a communication network of the present invention is that no additional and dedicated bandwidth is required. Furthermore, the method to improve signal quality in a communication network of the present invention will not delay the communication such as in the technique of informing the transmitter back and forth. In system such as time-division multiple access (TDMA), the time slot provided for transmitting user data will reduce the time used to retransmitting the same data over and over again and increase the efficiency when is used for retransmitting the same data.

Description

A METHOD TO IMPROVE SIGNAL QUALITY IN A COMMUNICATION NETWORK

FIELD OF THE INVENTION

The present invention relates a method to improve signal quality in a communication network more particularly for error data detection and correction.

BACKGROUND OF THE INVENTION

In either wired or wireless data transmission, bad signal quality can be caused by several factors such as interference, transmission media impairments and transmission channel condition. Among examples of interference are transmitter and electrical interference. Transmitter interference is the conditions whereby the communication device pick up unwanted signal from a nearby transmitter which may be contributing to poor signal quality. As an example, we may experience the nuisance while talking on the telephone. On the other hand, electrical interference is the term used to describe short bursts of interference which may be caused by electrical appliances such as garage door, microwave oven or even the communication device itself. Transmission media impairments is a property of a transmission medium which causes the signal to be degraded, reduced in amplitude, distorted or contaminated. Impairment can introduce errors into digital signals which result in the original data become corrupted. Among examples of transmission impairments are attenuation, delay distortion, and several sources of noise including, thermal noise, impulse noise, and inter-modulation noise. In the wired communication such transmission media is known as coaxial cable and fiber optic cable. Whereas in wireless communication, air is the only transmission media used. While interference and transmission media may be applicable to both wired and wireless signal degradation factor, channel propagation impairment is commonly described for wireless communication environment. Channel impairments can be categorized into several conditions such as path loss, multipath fading and shadow fading.

One of the results of such impairments described above is the reduction of data throughput in the system. This is due to the fact that, when the corrupted data is received, the quality data gathered at the receiver will be less. This is definitely causing the data packet to contain unreliable information to the users. In practice some of these impairments to the corrupted data can be determined and restored into the original transmitted data. Among popular techniques to do this is by detecting and correcting the corrupted data at the receiver end in order to obtain the less error data in the packet. If correction was not carried out, an acknowledgement via feedback channel will be sent to the transmitter to ask for retransmission of the same data. This process will be continuously performed until the data received is good enough to be decoded as the original information sent.

However, the use of feedback channel has it owns drawback in communication network. Firstly, an additional and dedicated bandwidth is required to allocate for such function. Since bandwidth is a scarce resource, having such requirement means that the use of bandwidth will no longer be efficient. Secondly, the technique of informing the transmitter back and forth will introduce delay in communication, thus in system such as time-division multiple access (TDMA), the time slot given for transmitting user data may cause inefficiency since more time is used to retransmitting the same data over and over again.

The present invention overcomes these and other deficiencies of the above-mentioned drawbacks by providing a method to improve signal quality in a communication network more particularly for error data detection and correction. The invention provides a considerable reduction of materials with even greater efficiency and economically during operation.

SUMMARY OF THE INVENTION

The present invention provides a method to improve signal quality in a communication network comprising of a) Buffering a received data and arranging the received data in overlapping arrangement;

b) Entering the received data into a sequence error detection and correction block in each node;

c) Comparing the received data with an estimated data;

d) Determining a path distance in each node from the difference between the received data with the estimated data;

e) Repeating Steps (c) and (d) until each node reaches a predetermined threshold value; f) Determining the estimated data having a lowest path distance in each node;

g) Replacing the received data with the estimated data as determined in step (f);

h) Retransmitting the estimated data if path distance determined in step (e) located at an intermediate node in each node.

In one embodiment of the present invention, step (a) further comprising of

Buffering the received data in serial; Providing each received data with a serial data symbol, y (n-1), y (n), and y (n+ 1) representation wherein n= 1 ,2,3...∞

Arranging the first received data and the next received data in serial sequence and overlapped each other.

In one of the embodiment, the overlapped data is entered into a sequence error detection and correction block in each node in parallel. A path truncation is implemented when the path distance provided a highest value in a node. In another embodiment of the present invention, step (c) further comprising of comparing the received data randomly assigned as the combination of digital bits either "1" or "0" with the predetermined estimated data having combination of digital bits either "1" or "0" in each node. In another embodiment of the present invention, step (d) further comprising of determining the difference between the received data and estimated data by assigning "0" for same digital bits and "1" if the digital bit of the received data and the digital bit of the estimated data are difference. In yet another embodiment of the present invention, step (e) further comprising of accumulating all the values of path distances and providing comparison between the path distances BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

Figure 1 illustrates a chart of a method to improve signal quality in a communication network in accordance of an embodiment of the present invention. Figure 2 illustrates a received data bits overlapping arrangement of a first mechanism in accordance of an embodiment of the present invention.

Figure 3 illustrates a sequence error detection and correction block of a second mechanism in accordance of an embodiment of the present invention.

Figure 4 illustrates a flowchart of a method to improve signal quality in a communication network in accordance of an embodiment of the present invention.

Figure 5 illustrates a receiver in a digital communication block in accordance of an embodiment of the present invention.

Figure 6 illustrates an example of the application of a method to improve signal quality in a wireless communication network in accordance of an embodiment of the present invention.

DETAILED DESCRIPTIONS OF THE INVENTION

The present invention will now be described in detail in connection with specific embodiments with reference to the accompanying drawings. Unless the context requires otherwise, throughout the specification and claims which follow, the word "comprise" and variations thereof, such as, "comprises" and "comprising" are to be construed in an open, inclusive sense that is as "including, but not limited to". Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, the appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. With respect to the use of substantially any plural and/or singular terms herein, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. The various singular/plural permutations may be expressly set forth herein for sake of clarity. Furthermore, in those instances where a convention analogous to "at least one of A, B and C," etc. is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., "a system having at least one of A, B and C" would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B and C together, etc.). In those instances where a convention analogous to "at least one of A, B or C, etc." is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., "a system having at least one of A, B, or C" would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B and C together, etc.). It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase "A or B" will be understood to include the possibilities of "A" or "B" or "A and B."

Figure 1 illustrates a flowchart of a method to improve signal quality in a communication network in accordance of an embodiment of the present invention. To complete the data detection and correction, the method of the present invention comprises of three mechanisms. The first mechanism (1 ) is sequence data gathered by overlapping technique followed by second mechanism (2), entering overlapped data into new sequence error detection and correction block for each node and determined the lowest path distance by comparing all the values of path distances and finally third mechanism (3), retransmission the corrected data.

In the first mechanism of the method of the present invention, each of the received data can be represented by such symbol set y(n-1),y(n),y(n+1 ), whereby n=1 ,2,3....∞. Each of these symbols set which consists of three minimum (3) or more data bits at a time is arranged in the overlapping manner in serial form. Such condition is required prior to entering the sequence error detection and correction block to keep the previous history of the symbol changed so that more accurate estimation of the original transmitted symbol can be determined. Figure 2 illustrates such overlapping symbol arrangement in this mechanism.

Once the overlapped data in first mechanism completed, each of this data or symbol set enters the sequence error detection and correction block in parallel in second mechanism as illustrated in Figure 3. The same symbol enters each of the nodes until the process is completed before the next symbol set enters into the sequence error detection and correction block. This is to make sure that each possible combination of the original transmitted symbol can be determined. The sequence error detection and correction block is provided in the beginning for once and to be used continuously as long as the data transmission is not terminated. The term "node" or "wireless node" or "network node" or "network station" may refer, for example, to a wireless station, e.g., a subscriber station or mobile station, an access point or base station, a relay station or other intermediate wireless node, or other wireless computing device, as examples.

At each entry of a node, the received data bit which is assumed as corrupted is compared with the estimated data. Path distance is further determined when a difference of 1 for each data that is not equaled to the estimated bits. For example, if the received data is 00, and the estimated data is 11 , then the path difference will be 2. This process is continued until the node reaches a depth of threshold value such as minimum 10 to maximum 50 nodes to the right of the block. The reason for such longer depth is to ensure the accuracy of the data to be corrected.

However, such longer depth will produce some complexity along the path if no truncation is provided. To overcome this complexity, the path truncation is carried out once the value of path distance is the highest at each node. Such high value indicates that how the received data is difference from the estimated symbols which represented that the data is in severe error thus to be disposed. When the process has reached to a depth of threshold value, the comparison is terminated for that particular symbol set and all the estimated symbols along the path are gathered and taken as the estimated symbols to be transmitted. The third mechanism also the final mechanism is to determine such error detection and correction functionality to be used to retransmit more quality data to its destination. In normal cases, such correction is completed at the end node destination but in the present invention, when the error is detected at the intermediate node such data is corrected and retransmitted until to the end of each destination. If the error is detected at end of the destination, no retransmission is required. Figure 4 illustrates a flowchart of a method to improve signal quality in a communication network in accordance of an embodiment of the present invention.

In operation, a method to improve signal quality in a communication network of the present invention is positioned at the receiver end part of a generic digital communication device as shown in Figure 5. A received data is buffered in serial and providing each received data with a serial data symbol, y (n-1), y (n), and y (n+1) representation wherein n= 1 ,2,3... °°. This data is then arranged wherein first received data and the next received data in serial sequence and overlapped each other. This process is continued until all the data arranged in serial sequence and overlapped each other completed. This data is then entered into a sequence error detection and correction block in each node in parallel. A comparison is made between the received data with an estimated data. The received data randomly assigned as the combination of digital bits either "1" or "0" with the predetermined estimated data having combination of digital bits either "1" or "0" in each node.

A path distance in each node from the difference between the received data with the estimated data is determined. The difference between the received data and estimated data is determined by assigning "0" for same digital bits and "1" if the digital bit of the received data and the digital bit of the estimated data are difference.

The comparison step and path distance determination step are repeated and continued until each node reaches a predetermined threshold value. All the values of path distances are then accumulated and a comparison between the path distances is provided. The estimated data having a lowest path distance in each node is determined. The received data having a lowest path distance is replaced with the estimated data. The estimated data is a corrected data and retransmitted if a path distance determined is located at an intermediate node in each node. During the process, a path truncation is implemented when the path distance provided a highest value in a node.

A method to improve signal quality in a communication network of the present invention is applied at either the intermediate node or the end destination of a receiver device in a wireless communication network. Such intermediate node can be a relay station as illustrated in Figure 6. The method of the present invention may be applicable to a wide variety of networks and technologies, such as WLAN networks (e.g., IEEE 802.1 1 type networks), IEEE 802.16 WiMAX networks, relay networks, mesh networks, 802.16 Mobile Multi-hop Relay (MMR) networks, as referenced in IEEE 802.16 WG, WiMedia networks, Ultra Wide Band networks, cellular networks, radio networks, or other wireless networks.

One of the advantages of the method to improve signal quality in a communication network of the present invention is that no additional and dedicated bandwidth is required. Furthermore, the method to improve signal quality in a communication network of the present invention will not delay the communication such as in the technique of informing the transmitter back and forth. In system such as time-division multiple access (TDMA), the time slot provided for transmitting user data will reduce the time used to retransmitting the same data over and over again and increase the efficiency when in used for retransmitting the same data. The transmitter and the receiver according to an embodiment of the present invention can be applied not only to the mobile communication system but also to a communication system for transmitting a data sequence including (i) a control information sequence indicating information with regard to data transmitted for efficient transmission of the data sequence and a data transmission format, and (ii) an error detection information bit sequence for detecting an error of the control information sequence.

The foregoing embodiment and advantages are merely exemplary and are not to be construed as limiting the present invention. The description of the embodiments of the present invention is intended to be illustrative and not to limit the scope of the claims and many alternatives, modifications and variations will be apparent to those skilled in the art.

Claims

1. A method to improve signal quality in a communication network comprising of i) Buffering a received data and arranging the received data in overlapping arrangement;

j) Entering the received data into a sequence error detection and correction block in each node;

k) Comparing the received data with an estimated data;

I) Determining a path distance in each node from the difference between the received data with the estimated data;

m) Repeating Steps (c) and (d) until each node reaches a predetermined threshold value;

n) Determining the estimated data having a lowest path distance in each node;

o) Replacing the received data with the estimated data as determined in step (f);

p) Retransmitting the estimated data if path distance determined in step (e) located at an intermediate node in each node. 2. The method as claimed in Claim 1 wherein step (a) further comprising of

Buffering the received data in serial;

Providing each received data with a serial data symbol, y (n-1), y (n), and y (n+ 1) representation wherein n= 1 ,

2,3...∞

3. The method as claimed in Claim 2 wherein the overlapped data is entered into a sequence error detection and correction block in each node in parallel.

4. The method as claimed in Claim 1 wherein a path truncation is implemented when the path distance provided a highest value in a node.

5. The method as claimed in Claim 1 wherein step (c) further comprising of comparing the received data randomly assigned as the combination of digital bits either "1" or "0" with the predetermined estimated data having combination of digital bits either "1" or "0" in each node.

6. The method as claimed in Claim 1 wherein step (d) further comprising of determining the difference between the received data and estimated data by assigning "0" for same digital bits and "1" if the digital bit of the received data and the digital bit of the estimated data are difference.

7. The method as claimed in Claim 1 wherein step (e) further comprising of accumulating all the values of path distances and providing comparison between the path distances.

8. The method as claimed in the preceding claims wherein the method is applied at either the intermediate node or the end destination of a receiver device in a wireless communication network.

9. The method as claimed in Claim 8 wherein the intermediate node is a relay station.