EXHIBIT 23

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(12) United States Patent 

Chun et al. 

US007869396 B2 

US 7,869,396 B2 

Jan. 11, 2011 

(10) Patent No.: 

(45) Date of Patent: 

(54) DATA TRANSMISSION METHOD AND DATA (58) Field of Classification Search ................. 370/231, 

RE-TRANSMISSION METHOD 370/328, 352, 346,394, 473, 241, 282,321; 

714/749; 455/67.11, 452.2, 455,464 

(75) Inventors: Sung Duck Chun. Anyang-si (KR): See application file for complete search history. 

Young Dae Lee, Anyang-si (KR); Sung (56) References Cited 

Jun Park. An -si (KR un Park, Anyang-si (KR) U.S. PATENT DOCUMENTS 

(73) Assignee: LG Electronics, Inc., Seoul (KR) 5,659,756 A 8, 1997 Hefferon et al. 

(*) Notice: Subject to any disclaimer, the term of this 

patent is extended or adjusted under 35 inued 

U.S.C. 154(b) by 133 days. (Continued) 

FOREIGN PATENT DOCUMENTS 

(21) Appl. No.: 12/158,646 

AU 2007-212916 8, 2007 

(22) PCT Filed: Jan. 3, 2007 

(86). PCT No.: PCT/KR2007/OOOO22 (Continued) 

S371 (c)(1), OTHER PUBLICATIONS 

(2), (4) Date: Jun. 20, 2008 Hua Xu et al., Performance Analysis on the Radio Link Control 

Protocol of UMTS System, Jul. 31, 2001, IEEE Publication, pp. (87) PCT Pub. No.: WO2007/078142 2026-2030 (http://ieeexplore.ieee.org/stampfstamp.jsp?tp= = ck PCT Pub. Date: Jul. 12, 2007 &arnumber=1040574&userType=inst). 

(Continued) (65) Prior Publication Data 

Primary Examiner Diane Mizrahi 

US 2008/O298322 A1 Dec. 4, 2008 (74) Attorney, Agent, or Firm—Lee, Hong, Degerman, Kang 

O O & Waimey Related U.S. Application Data 

(60) Provisional application No. 60/815,722, filed on Jun. (57) ABSTRACT 

21, 2006, provisional application No. 60/797,402, 

filed on May 2, 2006, provisional application No. A method which can reduce loss in data transmission is pro 

6O7784,976, filed on Mar. 22, 2006, provisional appli- vided. A data block is prepared in a high-level layer and the 

cation No. 60/757,063, filed on Jan. 5, 2006. data block is transmitted in a low-level layer. Status report 

O O information associated with reception or non-reception of the 

(30) Foreign Application Priority Data data block is received through the low-level layer. When a 

Dec. 22, 2006 (KR) ...................... 10-2006-O132469 receiver fails to receive data transmitted from a transmitter, the transmitter can rapidly recognize the reception failure and 

(51) Int. Cl. can retransmit the data. 

H0474/00 (2009.01) 

(52) U.S. Cl. ...................................................... 370/328 10 Claims, 8 Drawing Sheets 

700 750 

-------------4- --4---- TRANSMTR RCWR 

Tx Ric THAra Rx HAra R. Ric RC poU 1st TX S510 

S500 NACK 

2. A TX SE 

ff-nack 

ck skie TX S550 S555 

S580 NACK 

-- 1 STATUS 

report 

Ack. STATUS INFORMATION 

INSEion S570 

sao S575 

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Page 3 

Huawei: “Further Considerations on Multiplexing Method of Shared 

Control Channel in Uplink Single-Carrier FDMA”, 3GPP TSG-RAN 

WG1, R1-051430 online, Nov. 7, 2005 retrieved on Jul. 24, 2008. 

Retrieved from the Internet: http://www.3gpp.org/ftp/TSG RAN/ 

WG1 RL1/TSGR1 43/Docs/R1-051430.zip> pp. 1-6. 

NTT Docomo et al.: Multiplexing Method of Shared Control Chan 

nel in Uplink Single-Carrier FDMA Radio Access, 3GPP TSG-RAN 

WG1, R1-051143 online, Oct. 10, 2005 retrieved on Jul. 24, 2008. 

Retrieved from the Internet: f/www.3gpp.org/ftp/tsg ran/wgli r11/ 

TSGR1 42bis/Docs/R1-051143.Zip> pp. 1-8. 

Philips: “Evolved Paging Indicators for LTE, 3GPP TSG-RAN 

WG2, R2-052985 online), Nov. 7, 2005 retrieved on Aug. 25, 

2008). Retrieved from the Internet: //www.3gpp.org/FTP/tsg ran/ 

WG2 RL2/TSGR2 49/Documents/R2-052985.zip> pp. 1, 2. 

Sarkar, S. et al. Common-Channel Soft Handoff in codma2000. The 

Paging Channel. IEEE Transactions on Microwave Theory and Tech 

niques. Jun. 2000, vol. 48, No. 6, pp.938 to 950, XPO11037998, ISSN 

0.018-94.80, abstract, section IV. 

NTT Docomo, et al.: “Paging Channel Structure for E-UTRADown 

link', 3GPP TSG-RAN WG1, R1-060034 online, Jan. 23, 2006 

retrieved on Aug. 25, 2008). Retrieved from the Internet: www. 

3g.ppl.org/ftp/tsg ran/WG 1. RL1/TSGR1 AH/ 

LTE AH January-06/Docs/R1-060034.zip pp. 1-5. 

Motorola: “Paging Channel Design for E-UTRA, 3GPP TSG-RAN 

WG1, R1-061712 online), Jun. 27, 2006 retrieved on Aug. 25, 

2008). Retrieved from the Internet: //www.3g.ppl.org/ftp/tsg ran/ 

WG1 RL1 TSGR1 AHLTE AH June-06, DocSR1-061712. 

Zip pp. 1-3. 

LG Electronics Inc.: “Framing in the MAC entity”, 3GPP TSG-RAN 

WG2, R2-061012, Mar. 27-31, 2006. 

LG Electronics Inc.: “HARQ and ARQ Operation”, 3GPP TSG-RAN 

WG2, R2-060106, Jan. 9-13, 2006. 

F.A. Zdarsky et al., “Handover in Mobile Communication Networks: 

Who is in Control Anyway?.” Proceedings of the 30th EUROMICRO 

Conference, Aug. 2004, XP-10723593A. 

LG Electronics Inc., “Framing in the MAC Entity.”3GPP TSG-RAN 

WG2 #52, R2-061012, Mar. 2006. 

LG Electronics Inc., “HARQ and ARQ Operation.”3GPP TSG-RAN 

WG2 #50, R2-060106, Jan. 2006. 

R.T. Derryberry et al., “On CDMA2000 Evolution Reverse High 

Speed Data Physical Layer Enhancements in CDMA 2000 lxEV 

DV.” IEEE Communications Magazine, Apr. 2005, vol.43, No. 4, pp. 

41-47, XP-001228792. 

J. Chung et al., “Packet Synchronization and Identification for Incre 

mental Redundancy Transmission in FH-CDMA Systems.” Third 

IEEE International Symposium on Personal, Indoor, and Mobile 

Radio Communications, Oct. 1992, pp. 292-295, XP-010107082. 

H. Xu et al., “Performance Analysis on the Radio Link Control 

Protocol of UMTS System.” IEEE Publication, Jul. 2001, pp. 2026 

2030. 

* cited by examiner 

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U.S. Patent Jan. 11, 2011 Sheet 1 of 8 US 7,869,396 B2 

Fig. 1) 

CN(Core Network) 30 

AG(Access Gateway) 

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U.S. Patent Jan. 11, 2011 Sheet 2 of 8 US 7,869,396 B2 

Fig. 4 

300 350 

----------------------- 4. r - -----------4----- 

TRANSMITTER RECEIVER 

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U.S. Patent Jan. 11, 2011 Sheet 3 of 8 US 7,869,396 B2 

STATUS 

REQUEST S310 

NFORMATION S320 

REPORT REPORT 

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Fig. 8) 

TRANSMITTER RECEIVER 

STATUS 

REPORT 

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Fig.11 

930 

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Fig. 12) 

 

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US 7,869,396 B2 

1. 

DATA TRANSMISSION METHOD AND DATA 

RE-TRANSMISSION METHOD 

This application is a national stage application of PCT/ 

KR2007/000022, filed on Jan. 3, 2007, which claims the 

benefit and right of priority to U.S. Provisional Application 

No. 60/757,063, filed on Jan.5, 2006, U.S. Provisional Appli 

cation No. 60/784,976, filed on Mar. 22, 2006, U.S. Provi 

sional Application No. 60/797,402, filed on May 2, 2006, 

U.S. Provisional Application No. 60/815,722, filed on Jun. 

21, 2006 and Korean Application No. 10-2006-0132469, filed 

on Dec. 22, 2006, the contents of which are hereby incorpo 

rated by reference herein in their entirety. 

TECHNICAL FIELD 

The present invention relates to wireless communication, 

and more particularly, to a data transmission method and a 

data retransmission method which can reduce loss in data 

transmission. 

BACKGROUND ART 

A 3GPP (3-rd Generation Partnership Project) mobile 

communication system based on a WCDMA (Wideband 

Code Division Multiple Access) radio access technology has 

been widely spread all over the world. An HSDPA (High 

Speed Downlink Packet Access) which can be defined as a 

first evolution step of the WCDMA provides a radio access 

technology having a high competitive power in a mid-term 

future for the 3GPP. However, since requirements and expec 

tations of users and providers have increased more and more 

and competitive development of the radio access technology 

has been made more and more, a new technological evolution 

of the 3GPP is required to enhance a high competitive power 

in the future. 

The 3GPP entered into a project called “Evolved UTRA 

and UTRAN' from the end of 2004 for the purpose of devel 

opment of a radio transmission technology which can provide 

a high-quality service and reduce cost. The project of 3G long 

term evolution (hereinafter, referred to as LTE) aims at expan sion of a coverage, improvement of system capacity, decrease 

in cost of users and providers and improvement in service 

quality. The 3G LTE defines as high-level requirements 

decrease in cost per bit, enhancement in service availability, flexible utilization of frequency bands, open interface with a 

simple structure and appropriate power consumption of by 

user equipments. 

In any communication system, data can be lost in a physical channel. With the development of technologies, the probabil 

ity that data are not transmitted well from a transmitter to a 

receiver in the physical channel is lowered, but does not 

disappear completely. Particularly, in case of user equipments 

spaced apart from a base station, the data loss rate is high. 

Important signaling data or control signals need be subjected 

to more special management for the purpose of reliability of 

the communication systems. 

One oftechniques used to reduce the loss of data is an ARQ (Automatic Repeat Request) method. Generally, the ARQ 

method is performed by a high-level layer. Lower-level layers 

perform HARQ (Hybrid ARQ), thereby reducing the loss of 

data. The HARQ uses a FEC (Forward Error Correction) and 

the ARQ together to correct an error of data by the use of the 

FEC and to retransmit the data by the use of the ARQ. 

When a receiver fails to receive data at the time of retrans 

mission, the reception failure should be rapidly reported to a 

transmitter. This is because it is possible to reduce the time for 

10 

15 

25 

30 

35 

40 

45 

50 

55 

60 

65 

2 

correction of an error and the time for Solving an obstacle to 

data transmission by allowing the transmitter to rapidly rec 

ognize the data reception failure. As the transmitter recog 

nizes more rapidly the reception failure, the time for retrans 

mission is more reduced. 

DISCLOSURE OF INVENTION 

Technical Problem 

There is a need for technologies for enhancing reliability of 

transmission by efficiently using the ARQ of the high-level 

layer and the HARQ of the low-level layer. 

Technical Solution 

An advantage of some aspects of the invention is to provide a data transmission method and a data retransmission method 

which can retransmit data, which are not received by a 

receiver, while efficiently using radio resources. 

In an aspect of the invention, a data block is prepared in a 

high-level layer and the data block is transmitted in a low 

level layer. Status report information associated with recep tion or non-reception of the data block is received through the 

low-level layer. 

In another aspect of the invention, a RLC (Radio Link 

Control) PDU (Protocol Data Unit) is prepared in a RLC layer 

and the RLC PDU is transmitted using a HARQ (Hybrid Automatic Repeat Request) in a physical layer. Status report 

information associated with reception or non-reception of the 

RLC PDU is received. Whether the RLC PDU should be 

retransmitted is determined on the basis of the status report 

information. 

In still another aspect of the invention, a data block is 

retransmitted a data block through an HARQ by a preset 

number of times in a physical layer. A reception of a NACK 

(Not ACKnowledgement) signal is reported to a RLC layer 

when receiving the NACK signal by the maximum allowable 

number of times. Whether the data block should be retrans 

mitted is determined. 

ADVANTAGEOUSEFFECTS 

When a receiver does not receive data transmitted from a 

transmitter, the transmitter can rapidly confirm the reception failure and retransmit the data. By transmitting status report 

information from the receiver to the transmitter through a 

physical layer, it is possible to relatively rapidly retransmit 

data. By providing operations of RLC entities for allowing 

data to arrive at the receiver without any error, it is possible to 

more rapidly transmit data and to enhance the QoS (Quality of 

Service). 

BRIEF DESCRIPTION OF THE DRAWINGS 

FIG. 1 is a block diagram illustrating a wireless commu 

nication system. 

FIG. 2 is a block diagram illustrating a control plane of a 

radio interface protocol. 

FIG. 3 is a block diagram illustrating a user plane of the 

radio interface protocol. 

FIG. 4 is a flowchart illustrating a data transmission 

method according to an exemplary embodiment of the inven 

tion. 

FIG. 5 is a flowchart illustrating a data transmission 

method according to another exemplary embodiment of the 

invention. 

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3 

FIG. 6 is a flowchart illustrating an example of transmis 

sion and reception of status report information. 

FIG. 7 is a flowchart illustrating another example of trans 

mission and reception of status report information. 

FIG. 8 is a flowchart illustrating a data transmission 5 

method according to another exemplary embodiment of the 

invention. 

FIG. 9 is a flowchart illustrating a data transmission 

method according to another exemplary embodiment of the 

invention. 10 

FIG. 10 is a block diagram illustrating a data transmission 

method according to another exemplary embodiment of the 

invention. 

FIG. 11 is a block diagram illustrating a handover accord 

ing to an exemplary embodiment of the invention. 15 

FIG. 12 is a diagram illustrating an example of a data 

transmission method according to an exemplary embodiment 

of the invention. 

FIG. 13 is a diagram illustrating an example of a data 

transmission method according to an exemplary embodiment 20 

of the invention. 

MODE FOR THE INVENTION 

Hereinafter, exemplary embodiments of the invention will 25 

be described in detail with reference to the attached drawings. 

FIG. 1 is a block diagram illustrating a wireless commu 

nication system. The wireless communication system may 

have a network structure of an E-UMTS (Evolved-Universal Mobile Telecommunications System). The E-UMTS may be 30 

a long term evolution (LTE) system. The wireless communi 

cation system is widely disposed to provide a variety of 

communication services of Voices, packet data and the like. 

Referring to FIG. 1, the E-UMTS network can be roughly 

classified into an E-UTRAN (Evolved-UMTS Terrestrial 35 

Radio Access Network) and a CN (Core Network). The 

E-UTRAN includes eNode-B 20 and an AG (access gateway) 

30 which is located at the end of the network and connected to 

an external network. 

A UE (User Equipment) 10 may be fixed or movable and 40 

can be called various terminologies such as a mobile station 

(MS), a user terminal (UT), a subscriber station (SS) and a 

wireless device. 

The eNode-B 20 generally means a fixed station commu 

nicating with the UE 10 and can be called various terminolo- 45 

gies Such as a base station (BS), a base transceiver system 

(BTS) and an access point (AP). One or more cells may exist 

in one eNode-B 20. An interface for transmitting a user traffic 

or a control traffic may be used between the eNode-Bs 20. 

The AG 30 is also called MME/UPE (Mobility Manage- 50 

ment Entity/User Plane Entity). The AG 30 may be divided 

into a portion for processing a user traffic and a portion for 

processing a control traffic. The AG for processing the user 

traffic and the AG for processing the control traffic can com 

municate with each other by the use of a new interface. 55 

The CN may include the AG 30 and a node for registering 

for other UEs 10. An interface for distinguishing the E-UT 

RAN and the CN from each other may be used. 

Layers of a radio interface protocol between the UE and the 

network can be classified into an L1 layer (first layer), an L2 60 

layer (second layer), and an L3 layer (third layer) on the basis 

of three low-level layers of an open system interconnection 

(OSI) model widely known in the communication systems. A 

physical layer belonging to the first layer provides an infor 

mation transfer service using a physical channel and a RRC 65 

(Radio Resource Control) layer located in the third layer serves to control radio resources between the UE and the 

4 

network. The RRC layer interchanges an RRC message 

between the UE and the network. The RRC layer can be 

distributed into the eNode-B and network nodes such as the 

AG or can be located locally in the eNode-B or the AG. 

The radio interface protocol horizontally includes a physi 

cal layer, a data link layer, and a network layer. The radio 

interface protocol vertically includes a user plane for trans 

mitting data and information and a control plane for transmit 

ting a control signal. 

FIG. 2 is a block diagram illustrating a control plane of the 

radio interface protocol. FIG.3 is a block diagram illustrating 

a user plane of the radio interface protocol. FIGS. 2 and 3 

illustrate a structure of the radio interface protocol between 

the UE and the E-UTRAN based on a 3GPP radio network 

standard. 

Referring to FIGS. 2 and 3, the physical layer as the first 

layer provides an information transfer service to a high-level 

layer by the use of a physical channel. The physical layer is 

connected to a MAC (Medium Access Control) layer as a 

higher-level layer through a transport channel. Data are trans 

mitted between the MAC layer and the physical layer through 

the transport channel. Data are transmitted between different 

physical layers, that is, between a transmission-side physical layer and a reception-side physical layer, through a physical 

channel. 

The MAC layer of the second layer provides a service to a 

RLC (Radio Link Control) layer as a higher-level layer 

through a logical channel. The RLC layer of the second layer 

supports the data transmission with reliability. The function 

of the RLC layer may be embodied by a functional block in 

the MAC layer and in this case, the RLC layer may not exist. 

A PDCP (Packet Data Convergence Protocol) layer of the 

second layer performs a head compression function of reduc 

ing ahead size of an IP packet containing unnecessary control 

information with a relatively large size in order to efficiently 

transmit packets in a radio interval having a small bandwidth 

at the time of transmitting an IP (Internet Protocol) packet 

Such as IPv4 or IPv6. 

The RRC layer located at the lowermost of the third layer is defined in only the control plane. The RRC layer controls 

the logical channel, the transport channel, and the physical channel associated with the configuration, re-configuration 

and release of the radio bearers (RB). The RB means a service 

provided from the second layer so as to transmit data between 

the UE and the E-UTRAN. 

A downlink transport channel for transmitting data from 

the network to the UE can include a broadcast channel (BCH) 

for transmitting system information and a downlink shared 

channel (SCH) for transmitting a user traffic or a control 

message. The traffic or the control message of the downlink 

multicast or the broadcast service may be transmitted through the downlink SCH or through a particular downlink MCH 

(Multicast Channel). An uplink transport channel for trans 

mitting data from the UE to the network can include a random 

access channel (RACH) for transmitting an initial control 

message and an uplink SCH (Shared Channel) for transmit 

ting a user traffic or a control message. 

The RLC layer has basic functions of guarantee of QoS 

(Quality of Service) of the RBs and transmission of data. 

Since the RB service is a service which is provided to a 

higher-level layer from the second layer in the radio protocol, 

the entire second layer affects the QoS and the affection of the 

RLC layer is the largest. The RLC layer has independent RLC 

entity for each RB so as to guarantee the QoS specific to the 

RB and three RLC modes of a unacknowledged mode (UM), 

an acknowledged mode (AM) and a transparent mode (TM) 

so as to support a variety of QoS. Two modes, that is, the UM 

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5 

not including an acknowledgement to transmitted data and 

the AM including the acknowledgement, will be described 

below. 

The UM RLC layer adds a PDU (Protocol Data Unit) 

header having a sequence number to each PDU and thus 

informs a receiver of a lost PDU. For this reason, in the user 

plane, the UM RLC layer takes charge of transmission of 

broadcast/multicast data or transmission of real-time packet data such as Voices (for example, VoIP) or streaming of a 

packet service domain. In the control plane, the UM RLC 

layer takes charge of transmission of an RRC message not 

requiring the acknowledgement among the RRC messages 

transmitted to a specific UE or a specific UE group in a cell. 

Similarly to the UM RLC layer, the AM RLC layer adds a 

PDU header having a sequence number at the time of consti 

tuting a PDU, but a receiver transmits the acknowledgement 

to the PDU transmitted from a transmitter unlike the UMRLC 

layer. This is designed to allow the receiver to request the 

transmitter for retransmission of the PDU which is not 

received by the receiver. The AMRLC layer guarantees error 

free data transmission through retransmission and thus the 

AM RLC takes charge of transmission of non-real-time 

packet data such as TCP/IP of the packet service domain 

mainly in the user plane and can take charge of transmission 

of RRC message requiring the acknowledgement. 

In view of directionality, the UM RLC layer is used in a 

uni-directional communication but the AMRLC is used in a 

bi-directional communication due to a feedback from the 

receiver. Since the bi-directional communication is mainly used for a point-to-point communication, the AMRLC layer 

uses only a specific logical channel. In view of a structure, one 

RLC entity of the UMRLC layer has only one of transmission 

and reception, but one RLC entity of the AM RLC layer 

includes both of transmission and reception. 

The complexity of the AM RLC results from the ARQ 

function. The AMRLC layer has a retransmission buffer in 

addition to a transmission/reception buffer so as to manage 

the ARQ, and performs a variety of functions of utilization of 

a transmission/reception window for a flow control, polling 

of allowing a transmitter to request a receiver of a peer RLC 

entity of status information, status report of allowing the 

receiver to report its buffer status to the transmitter of the peer 

RLC entity and piggyback of inserting the status PDU into the 

data PDU so as to enhance the efficiency of data transmission. 

In addition, the functions of the AMRLC layer include a reset 

PUD requesting the opposite AMRLC entity to reset all the 

operations and parameters when the AMRLC entity finds out 

an fatal error in the course of operation and a reset ACKPDU 

used in acknowledgement of the reset PDU. In order to sup 

port the functions, the AMRLC requires a variety of protocol 

parameters, status variables and timers. The PDUs used for 

report of the status information or control of the data trans 

mission by the AMRLC layer, such as the status PDU and the 

reset PDU are called control PDUs. The PDUs used for trans 

mission of user data are called data PDUs. 

Radio resources in one cell include uplink radio resources 

and downlink radio resources. The eNode-B takes charge of 

assignment and control of the uplink radio resources and the 

downlink radio resources. The eNode-B determines when a 

UEuses a radio resource, what a UEuses a radio resource and 

what radio resource a UE uses. For example, the eNode-B 

may determine that frequencies of 100 MHz to 101 MHZ are 

assigned to the UE for 0.2 seconds in 3.2 seconds for the 

downlink data transmission. Then, the base station informs 

the corresponding UE of the de-termination details so as to 

allow the corresponding UE to receive the downlink data. 

Similarly, the eNode-B determines when a UE uses a radio 

5 

10 

15 

25 

30 

35 

40 

45 

50 

55 

60 

65 

6 

resource, what a UE uses a radio resource and what radio 

resource a UEuses so as to transmit uplink data. The eNode-B 

transmits such information to the corresponding UE. In this 

way, the eNode-B can dynamically manage the radio SOUCS. 

A conventional UE continuously used one radio resource 

during a call connection. This is irrational in consideration of 

the fact that many recent services are based on IP packets. 

Most packet services do not continuously create packets dur 

ing the call connection, but there are many intervals where no 

data is transmitted. It is not efficient that a radio resource is 

continuously assigned to a UE. A method of assigning a radio 

resource to a UE only when service data exist can be used to 

solve the above-mentioned problem. 

The RLC entity constitutes a RLC PDU in accordance with 

the size of the radio resource determined by the MAC. The 

RLC entity located in the eNode-B constructs data with the 

size determined by the MAC entity and sends the RLC PDU 

to the MAC entity. The RLC entity located in the UE con 

structs the RLC PDU in accordance with the size of a radio 

resource determined by a lower-level layer, that is, the MAC 

entity. The RLC entity located in the UE constructs data with 

the size determined by the MAC entity and sends the RLC 

PDU to the MAC entity. 

The MAC entity located in the UE receives information on 

the total amount of radio resources from the eNode-B. The 

MAC entity receives information indicating what amount of 

radio resources the MAC entity can use at the next transmis 

sion time from the eNode-B. On the contrary, the MAC entity 

located in the eNode-B determines utilization of all of the 

uplink radio resources and the downlink radio resources. The 

MAC entity of the eNode-B determines what amount of radio 

resources should be assigned to the UE at the next transmis 

sion interval and sends the determination result to the MAC 

entities of the UEs. The UEs determine what amount of data 

should be transmitted through the logical channels or by the 

RLC entities in consideration of data stored in their buffers 

and priorities thereof. Each RLC entity determines the size of 

the RLC PDU to be transmitted to the MAC entity. Similarly, 

the MAC entity located in the eNode-B determines what 

amount of data should be assigned to the respective RLC 

entities in consideration of the amount of downlink data of the 

respective UEs and the priorities of the data and sends the 

determination result to the respective RLC entities. The 

respective RLC entities construct a RLC PDU in accordance 

with the determination result and transmit the constructed 

RLC PDU to the MAC entity. 

The PDU is a basic data unit used for data communication 

between layers. The PDU is a data which is transmitted from 

a corresponding layer to a different layer. A RLC PDU, a 

MAC PDU and the like are examples of the data used by the 

layers. An SDU (Service Data Unit) is a data unit from a 

different layer to the corresponding layer. 

FIG. 4 is a flowchart illustrating a data transmission 

method according to an exemplary embodiment of the inven 

tion. Tx RLC denotes a RLC entity in a transmitter 30 and Tx 

HARO denotes a lower-level layer of the RLC layer for 

performing the HARQ in the transmitter 300. RX RLC 

denotes a RLC entity in a receiver 350 and Rx HARQ denotes 

a lower-level layer of the RLC layer for performing the 

HARQ in the receiver 350. The HARQ is mainly performed in the physical layers. The HARQ operation may be per 

formed using the MAC PDU and the ARQ operation is at a 

level higher than the HARQ operation. 

Referring to FIG.4, the RLC PDU is transmitted to the TX 

HARQ from the Tx RLC (S100). The RLC PDU is transmit 

ted to the MAC layer and can be converted into one or more 

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receiver 450 sends information on the RLC PDUs not 

received by the receiver 450 to the transmitter 400 and the 

transmitter 400 then transmits the corresponding RLC PDUs. 

When the radio resources are not sufficient, the transmitter 

400 can transmit RLC Sub-PDU into which the RLC PDU is 

divided. 

The status report information is transmitted and received 

using the physical layer so as to allow the transmitter 400 and 

the receiver 450 to rapidly exchange the ARQ information. 

The status report information can be transmitted using a chan 

nel defined by the physical layer, not by the level of the RLC 

PDU or the MAC PDU. When receiving the status report 

information, the physical layer sends the received status 

report information to a higher-level RLC entity. When it is 

necessary to transmit status report information, the RLC 

entity sends the status report information directly to the 

physical layer and the physical layer can send the status report 

information using a physical channel other than the channel 

through which data are transmitted. 

The status report information can be transmitted through a 

channel through which scheduling information indicating the 

assignment of physical resources in the physical layer is 

transmitted. The status report information may be informa 

tion on a data block received or not received by the RLC entity of the receiver. Alternatively, the status report information 

may be information on a data block not to be transmitted by 

the RLC entity of the transmitter or information on a data 

blockabandoned by the transmitter. When it is informed that 

a specific data block is not transmitted from the transmitter 

any more, the RLC of the receiver 450 can stop the waiting of 

the RLC PDU and process the data blocks stored in its buffer. 

The receiver 450 can add the status report information to a 

head portion of a data block. The data block may be a RLC 

PDU or a MAC PDU. The status report information may be 

information on the data blocks not received by the receiver 

450. The receiver 450 may not allow the status report infor 

mation to include information on the data blocks received by 

the receiver. 

When the RLC entity or the logical channel is particularly 

mapped with the HARQ process in order to reduce the over 

head of the data blocks in the high-level layers, several fields 

can be omitted. For example, when RB 1 is mapped with 

HARO process 1 in one to one, a TSN or a logical channel 

identifier can be omitted from the data block transmitted to 

HARQ 1. 

The receiver uses the physical layer to more rapidly and 

effectively send the status report information. When a data 

block not received by the receiver exists in the time interval 

received by the receiver, the receiver may inform the trans 

mitter of the fact by using a signaling through the physical 

channel. For example, when the receiver transmits signals to 

the receiver through a physical control channel every time 

interval, the receiver can inform the transmitter whether the 

receiver receives the data transmitted from the transmitter in 

the previous time interval through the physical channel. 

When the receiver informs the transmitter that the receiver 

does not receive the data block in the previous time interval 

through the physical channel, the transmitter can perform the 

retransmission of the data block. At this time, the information 

transmitted from the receiver to the transmitter indicates in 

what time interval the receiver fails to receive the data block. 

When the receiver fails to receive the data block transmitted 

from the transmitter, the receiver may inform the transmitter 

of the information on the time interval when the reception 

failure occurs. 

In an exemplary embodiment, the information on the time 

interval transmitted from the receiver to the transmitter can 

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include information on the reception Success and failure of 

the receiver for all the transmission from the transmitter in the 

time interval, which is set in a constant size by the receiver, or 

occurrence time information thereof. In another exemplary 

embodiment, the information on the time interval transmitted 

from the receiver to the transmitter can include information 

on the reception failure of the receiver for all the transmission 

from the transmitter in the time interval, which is set in a 

constant size by the receiver, or occurrence time information 

thereof. In still another exemplary embodiment, the informa 

tion on the time interval transmitted from the receiver to the 

transmitter can include information on the reception Success 

and failure of the receiver for the transmission from the trans 

mitter or occurrence time information thereof. In still another 

exemplary embodiment, the information on the time interval 

transmitted from the receiver to the transmitter can include 

information on the reception failure of the receiver for the 

transmission from the transmitter or occurrence time infor 

mation thereof. 

When the transmitter receives the information on the 

reception failure or the time information thereof, the trans 

mitter can make an appointment of retransmission of the 

corresponding data regardless of the reception of the status 

report information from the receiver. The transmission of the 

information on the reception failure or the time information 

thereof can be performed by a physical layer or a MAC entity. 

A physical layer or a MAC layer of the transmitter having 

received the information on the reception failure or the time 

information thereoftransmitted from the receiver may inform 

the RLC layer of the information. The RLC entity of the 

transmitter having received the information on the reception 

failure or the time information thereof transmitted from the 

receiver may retransmit the corresponding RLC PDU or RLC 

SDU and reconstruct the RLC PDU as needed. 

FIG. 6 is a flowchart illustrating an example of transmis 

sion and reception of the status report information. The status 

report information can be transmitted to the transmitter in a 

state where it is arbitrarily or previously set by the receiver. 

Alternatively, in order to more rapidly check the status report 

information, the transmitter may request for the transmission 

of the status report information through status request infor 

mation. 

Referring to FIG. 6, the Tx HARQ transmits status request 

information to the Rx HARQ (S310). The status request infor 

mation request the receiver for transmitting the status report 

information. The status request information allows the trans 

mitter 500 and the receiver 550 to more rapidly exchange the 

status report information. The status request information is 

information indicating that the receiver 550 should rapidly 

construct and transmit the status report information. When 

receiving the status request information, the Rx HARQ 

informs the Rx RLC of the fact (S320). The Rx RLC con 

structs and sends the status report information to the RX 

HARQ (S330). The Rx HARQ transmits the status report 

information (S340). 

When a predetermined condition is satisfied, the physical 

layer of the transmitter 500 can transmit the status request information through a physical channel different from the 

physical channel through which data are transmitted. For 

example, when the physical layer performs the retransmis 

sion the same number of times as the maximum number of 

times of HARQ retransmission set in the data block transmit 

ted by the physical layer, the physical layer can set and trans 

mits the status request information. 

The status report information or the status request infor 

mation can be transmitted through a control information 

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transport channel which is used in the physical layer to trans 

mit the scheduling information. 

FIG. 7 is a flowchart illustrating another example of trans 

mission and reception of the status report information. 

Referring to FIG. 7, the Tx RLC requests for the status 

request information (S410). The status request information 

may be requested by a higher-level layer as well as the physi 

cal layer. When the buffer of the RLC entity is empty, for 

example, when the final RLC PDU has been transmitted, the 

RLC entity can request for the status requestinformation so as 

to receive the status report information from the receiver 650. 

The Tx HARQ transmits the status request information to the 

Rx HARQ (S420). When receiving the status request infor 

mation, the Rx HARQ informs the Rx RLC of the fact (S430). 

The Rx RLC constructs and sends the status report informa 

tion to the Rx HARQ (S440). The Rx HARQ transmits the 

status report information (S450). 

FIG. 8 is a flowchart illustrating a data transmission 

method according to another exemplary embodiment of the 

invention. 

Referring to FIG.8, the RLC PDU is sent from the Tx RLC 

to the Tx HARQ (S500). The Tx HARQ transmits a data 

block to the Rx HARQ (S510). When an error is detected 

from the data block, the Rx HARQ transmits an NACK signal 

to the Tx HARQ (S520). The Tx HARQ transmits the retrans 

mission data block to the Rx HARQ (S530). An error is 

detected in the second transmission and the Rx HARQ trans 

mits the NACK signal to the Tx HARQ (S540). In this way, 

the transmission can be repeated by L. times which is the 

maximum allowable number of times (S550). 

When an error is detected in the final transmission, the RX 

RLC is requested for constructing the status report informa 

tion (S555). The Rx RLC constructs and sends the status 

report information to the Rx HARQ (S570). When an erroris 

detected and the Rx HARQ transmits the NACK signal, the 

Tx HARQ may recognize the NACK signal as the ACK signal 

(S560). The Rx HARQ transmits the status report information 

to the Tx HARQ (S575). The status report information is 

reported to the Tx RLC (S580). Accordingly, even when an 

error occurs from the ACK/NACK signal, the RLC can accu 

rately judge whether the retransmission should be performed 

on the basis of the status report information. 

Independently of the status report information, the physi 

cal layer can transmit particular information to more effec 

tively transmit the ACK/NACK signals between the HARQ. 

When the transmitter performs the final HARQ process of a 

specific data block, the transmitter can transmit particular 

information indicating that the final HARQ of the specific data block is being transmitted, through the physical layer. 

FIG. 9 is a flowchart illustrating a data transmission 

method according to another exemplary embodiment of the 

invention. It relates to a method of allowing the RLC entity to 

cope with an emergency. 

Referring to FIG.9, the Tx RLC transmits a RLC PDU to 

the receiver 850 (S600). When the first transmission fails, the 

Tx RLC performs the retransmission. The retransmission can 

be repeated by N times which is the maximum allowable 

number of times (S610). When the N-th transmission fails, 

the Tx RLC informs the RX RRC of the failure (S630). 

When the case where the transmitter 800 transmits a spe cific data block but does not receive an acknowledgement 

from the receiver 850 is repeated a predetermined number of 

times or more, the RLC layer may inform a higher-level layer 

of resetting a communication condition. When the RRC is 

informed by the RLC that it transmits a data block a prede 

termined number of times or more but does not receive an 

acknowledgement from the opposite party, the RRC solve 

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this problem by using the RRC signaling of the higher-level 

layer. The RRC signaling means that the transmitter and the 

receiver transmit an RRC message to each other. In this case, 

the RRC can reset the RLC. 

When transmitting the specific data block several times but 

not receiving an acknowledgement from the receiver 850, the 

Tx RLC may stop the transmission of the data block. Tx RLC 

may inform the Tx RRC as a higher-level layer of this fact, 

and waits for an instruction therefrom. Alternatively, when 

recognizing an abnormal operation in the transmission of the 

specific data block, the TX RLC may not process Such a 

situation, but inform the RRC as a higher-level layer of the 

situation and comply with an instruction therefrom. 

FIG. 10 is a block diagram illustrating a data transmission 

method according to another exemplary embodiment of the 

invention. 

Referring to FIG. 10, the transmitter sequentially transmits 

RLC PDUO, RLC PDU1, RLC PDU2, RLC PDU3, and RLC 

PDU4 and the receiver receives successfully RLC PDUO and 

RLC PDU1 but fails to receive RLC PDU2. Since failing to 

receive RLC PDU2, the receiver loads the information on 

RLC PDU2 to the status report information. 

RLC PDU2 includes a part of RLC SDU1 and a part of 

RLC SDU2. When the receiver transmits the status report 

information based on the information of the SDU, the receiver 

should transmit at least two information pieces, that is, infor 

mation pieces on RLC SDUO and RLC SDU1. On the con 

trary, when the receiver transmits the status report informa 

tion based on the information of the PDU, the receiver can 

transmit only one information piece, that is, the information 

on the RLC PDU2. Accordingly, by transmitting the status 

report information based on the information of the PDU, it is 

possible to reduce the amount of data to be transmitted. 

The PDU can be expressed in various ways. For example, 

the PDU can be expressed as what portion of the SDU is 

addressed by the data included in the PDU or as sequence 

number assigned to each PDU. In order to allow the transmit 

ter and the receiver to easily manage the PDUs, the status 

report information can be managed based on the sequence 

numbers. 

FIG. 11 is a block diagram illustrating a handover. 

Referring to FIG. 11, a source eNode-B 910 denotes an 

current eNode-B and a target eNode-B 920 denotes a new 

base station after the handover. When the source eNode-B 

910 and the target eNode-B920 have different information 

associated with the status report information of a UE900 or 

the target eNode-B 920 does not have the latest status report information, unnecessary transmission may cause. The trans 

mission of new data may be delayed due to the unnecessary 

transmission, thereby deteriorating the QoS. When a han 

dover occurs, the UE900 retransmits the SDUs, for which no 

acknowledgement is received from the source eNode-B to the 

target eNode-B920. 

The UE900 can reconstruct the RLC SDU into the RLC 

PDU and transmit the re-constructed RLC PDU to the target eNode-B 920. Alternatively, the source eNode-B 910 can 

transmit the latest status report information to the target 

eNode-B 920 and the target eNode-B 920 can transmit the 

latest status report information to the UE900. 

The SDU which is transmitted from the eNode-B to the AG 

in the course of the handover can be classified into two kinds, 

that is, SDU which the source eNode-B 910 transmits to the 

AG 930 and SDU which the target eNode-B920 transmits to 

the AG930. When the handover does not occur, the eNode-B 

rearranges the SDU received from the UE, but when the 

handover occurs, both eNode-Bs transmit the SDU to the AG 

930 and thus any eNode-B cannot rearrange the SDU. The AG 

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930 should check all the SDUs transmitted from the source 

eNode-B910 and the target eNode-B920 and rearrange the 

SDUs. Right after the handover, the target eNode-B 920 

transmits the SDU to the AG 930 every when restoring the 

SDUs, for a predetermined time, that is, until the handover is 

completed. 

The target eNode-B 920 can transmit to the AG 930 the 

RLC SDUs received successfully itself by the use of the time 

information of the handover. The time information of the 

handover can be received from the source eNode-B 910. 

The target eNode-B 920 can transmit the RLC SDU suc 

cessfully received from the UE900 to the AG 930 at once for 

a predetermined time after the handover is made. The time 

information can be used to determine how long the target 

eNode-B920 transmits the RLC SDU successfully received 

to the AG 930. The time information may be valid from the 

time point when the instruction for the handover is received 

from the source eNode-B 910. Alternatively, the time infor 

mation may be valid from the time point when the target 

eNode-B 920 receives a message associated with the han 

dover from the UE900. 

For a predetermined time from the time point when the UE 

900 accesses the targeteNode-B920, the targeteNode-B920 

may not rearrange but transmit the RLC SDU successfully 

received from the UE900 to the AG 930 at once. The target 

eNode-B 920 may receive the time information from the 

source eNode-B910 and not rearrange but transmit the RLC 

SDU successfully received from the UE900 to the AG 930 at 

once until the time point instructed by the time information. 

After the predetermined time, the target eNode-B 920 may 

rearrange and transmit the successfully received RLCSDU to 

the AG 930. 

When receiving the RLC SDU having a sequence number 

Smaller than the sequence number designated by the Source 

eNode-B 910, the target eNode-B 920 can transmit the 

received RLC SDU to the AG 930 at once. The UE 900 

transmits the sequence number information at the time of 

accessing the target eNode-B920 and the target eNode-B920 can transmit the received RLC SDU to the AG 930 at once 

when receiving the RLC SDU having a sequence number 

smaller than the sequence number. The UE900 can inform the 

target eNode-B 920 of the largest sequence number of the 

sequence numbers of the RLC SDUs which have been trans 

mitted to the source eNode-B910 at the time of first accessing 

the target eNode-B920. 

On the other hand, the optimization process may be carried 

out in the downlink direction. In a new cell, the UE 900 

transmits a handover completion message to the target 

eNode-B920. In the course, the targeteNode-B920 transmits 

a response message to the handover completion message. The 

UE 900 informs the target eNode-B 920 of the largest 

sequence number of the sequence numbers of the SDUs suc 

cessfully and continuously received by the UE 900 for the 

downlink data successfully received by the UE 900. The 

target eNode-B920 can newly transmit only the SDUs having 

a sequence number larger than the acquired sequence number 

to the UE900. It is possible to reduce the burden of the UE 

900 which classifies and rearranges the SDUs received from 

the target eNode-B920 and the source eNode-B 910. 

Hereinafter, operation of the ARQ and the HARQ is 

described. 

The HARQ with an N-channel SAO (Stop-And-Wait) is 

advantageous for a higher transmission rate. In the HARO. 

while one process performs the transmission and then waits 

for a response thereto, another process performs the transmis 

Sion. By reducing idle time in the transmission, it is possible 

to enhance the transmission rate. However, since the radio 

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conditions are often changed, the qualities of radio intervals 

to be actually experienced may be different from each other 

between continuous processes. Accordingly, the process hav 

ing started the transmission does not always finish the trans 

mission earlier. Therefore, the receiver should be able to 

perform the rearrangement and thus includes a buffer for 

performing the rearrangement. 

The ARQ entity, that is, the RLC entity operating in the AM 

mode, includes a buffer. This is because all the portions of the 

SDU should be stored in the buffer of the receiver until all the 

PDUs including a specific portion of the SDU arrive. If a gap 

occurs in the buffer of the receiver, it means that a specific 

RLC PDU is not received. If a gap occurs in the buffer of the 

HARO, it also means that a specific MAC PDU is not 

received. Since the RLC PDUs constitute the MAC PDUs, the 

gap in the RLC buffer and the gap in the HARQ buffer are 

associated with each other. It is possible to perform the buffer 

management in comprehensive consideration of two gaps. 

The rearrangement in the HARQ and the RLC PDUs received 

by the RLC can be simultaneously considered using only one 

buffer. 

The MAC PDUs are decomposed as soon as being received 

and then are sent to the RLC entities. In order for the RLC 

entity to solve the gap generated due to the N-channel SAW in 

the MAC, the RLC entity should check whether the gap generated in the RLC buffer is due to the reception failure or 

the inversion of transport order generated due to the N-chan 

nel SAW. The buffer of the RLC entity can use a timer. When 

a gap is generated in the buffer of the RLC entity, the timer is 

activated at once. When data corresponding to the gap is not 

received until the timer expires, it is judged that the gap is 

generated due to the reception failure and the status report 

information may be transmitted to the transmitter. 

FIG. 12 is a diagram illustrating an example of a data 

transmission method according to an exemplary embodiment 

of the invention, where a MAC layer (RX MAC) and a RLC 

layer (RX RLC) in the receiver are shown. 

Referring to FIG. 12, in CD, the ARQ entity, that is, the 

RLC entity, receives PDU3 from the HARQ as a lower-level 

layer, that is, the MAC layer. Since PDU2 having a sequence 

number smaller than that of PDU3 does not exist, the receiver 

checks that the gap is generated due to the inversion of trans 

port order of the HARQ by the use of the HARQjitter timer 

JT. 

In (2), the RLC entity receives PDU2 before the HARQ jitter timer JT expires, and the HARQ jitter timer JT stops. 

In (3), similarly to CD, since the ARQ entity received 

PDU6 having a sequence number smaller than that of PDU7. 

the HARQ jitter timer JT is activated. 

In (4), although the HARQjitter timer JT expires, the RLC 

entity cannot receive PDU6. The receiver judges that the 

reception of PDU6 fails and transmits the status report infor 

mation associated therewith to the transmitter. 

When receiving the status report information indicating 

that the receiver does not receive a certain PDU from the 

receiver, the transmitter retransmits the corresponding PDU. 

A timer may be set in each data block so as to prevent a 

deadlock. When the timers set in the SDUs expire, the pieces 

of the SDUs are not transmitted any more even when the 

reception failure is reported from the receiver. 

When receiving a data block having a sequence number 

outside the current window, the receiver adjusts the boundary 

of the window. The operation of the receiver uses the timer 

and the reception window. 

FIG. 13 is a diagram illustrating an example of a data 

transmission method according to an exemplary embodiment 

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US 7,869,396 B2 

15 

of the invention, where RLCs serving as an AM in the trans 

mitter and the receiver are shown. 

Referring to FIG. 13, in CD, SDU1 arrives at the buffer of 

the transmitter and a discard timer DT is activated. In (2), 

SDU2 arrives at the buffer of the transmitter and a discard 

timer DT is activated. The discard timers DT serve to define 

the maximum delay time set in the RLC entities. 

In (3), the receiver receives PDU3 and recognizes that 

PDU2 having a sequence number smaller than that of PDU3 

dose not arrive yet. In order to check whether the reception 

failure is generated due to the inversion of transfer order of the 

HARO, the receiver starts the HARQjitter timer J.T. 

In (4), when the HARQjitter timer JT expires, the receiver 

reports to the transmitter that it does not receive PDU2. At the 

same time, in order to prevent the report from being lost, a 

periodic timer PT for PDU2 is activated. 

In (5), the transmitter receives the report transmitted from 

the receiver. Since the discard timer DT for SDU1 does not 

expire yet, the transmitter retransmits PDU2. 

In (6), the discard timer DT for SDU1 expires. The pieces 

of SDU1 are not transmitted any more. At this time, the 

transmitter may inform the receiver that the discard timer DT 

for SDU1 expires and thus it does not transmit the pieces of 

SDU1 any more. It is possible to prevent waste of radio 

resources by preventing an unnecessary retransmission 

request. 

In (7), the periodic timer PT for PDU2 expires. Since the 

receiver does not receive PDU2 hitherto, the receiver trans 

mits the status report information for PDU2 again. The peri 

odic timer PT may be activated again at the same time of 

transmitting the status report information. 

In (8), since the transmitter receives the status report infor 

mation transmitted from the receiver again but the transmitter 

discards SDU1 due to the expiration of the discard timer DT. 

PDU2 is not retransmitted any more. 

In (9), a release timer RT for SDU2 expires in the receiver. 

The release timer RT is activated when the successfully reconstructed SDU cannot be sent to a higher-level layer 

because an SDU having a sequence number Smaller than that 

thereof does not arrive at the receiver. For example, the 

receiver successfully receives SDU2 by receiving a part of 

PDU3, PDU4, and PDU5, the receiver does not complete the 

reception of SDU1 having a sequence number Smaller than 

that of SDU2 because not receiving PDU2. At the time of 

receiving SDU2, the release timer RT is activated. The release 

timer RT is used to prevent a certain SDU from staying in the 

buffer of the receiver too long. When the release timer RT 

expires, the receiver sends succeeded SDU2 to a higher-level 

layer and does not wait for failed SDU1 or PDUs associated 

the failed SDU (PDU2) any more. Since not waiting PDU2 

any more, the periodic timer PT is also stopped. 

It is possible to manage the retransmission request by the 

use of only the buffer of the RLC layer without using the 

buffer of the MAC layer. 

The ARQ used here may be a NACK based system. The 

NACK based system is effective when data are steadily trans 

mitted. More fine operations are required in consideration of 

transmission of packets or user data transmitted intermit 

tently or the final SDU or PDU of a certain data flow. The 

NACK based system can be used when certain data is not 

received and the reception failure is checked by the receiver. 

The receiver transmits the status report information as 

information on data not received. When the transmission of 

data is intermittent, that is, when the size of data is very Small, 

the receiver may not know the transmission of data itself and 

the receiver cannot thus transmit the status report informa 

tion. In this case, the receiver needs to report the transmitter 

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that the receiver receives the data successfully. The transmit 

ter also needs to request the receiver to transmit the status 

report information. In an exemplary embodiment, a PDU may 

contain a command for requesting the receiver to transmit the 

status report information. In another exemplary embodiment, 

for the purpose of more rapid transmission, the transmitter 

may directly command the receiver to transmit a report through a physical channel through which the scheduling 

information is transmitted. 

The receiver should transmit the status report information 

to the transmitter as soon as it receives the request for the 

status report information. When not receiving the status 

report information within a predetermined time, the transmit 

ter can automatically retransmit the data. When the timer is 

used, the retransmission can be performed regardless of the 

status report information. 

The present invention can be embodied in hardware, soft 

ware, or combinations thereof. Examples of the hardware can 

include an ASIC (Application Specific Integrated Circuit), a 

DSP (Digital Signal Processing), PLD (Programmable Logic 

Device), an FPGA (Field Programmable Gate Array), a pro 

cessor, a controller, a micro processor, other electronic units, 

and combinations thereof, which are designed to perform the 

above-mentioned functions. In Software, the invention can be 

embodied by modules for performing the above-mentioned 

functions. The Software can be stored in a memory unit and 

executed by a processor. As the memory unit or processor, 

means well known to those skilled in the art can be employed. 

Although the embodiments of the present invention have 

been described in detail with reference to the attached draw 

ings, it should be understood by those skilled in the art that the 

invention can be modified and changed in various forms 

without departing from the technical spirit and scope of the 

invention. Accordingly, the invention is not limited to the 

above-mentioned embodiments, but includes all the embodi 

ments without departing from the scope of the appended 

claims. 

The invention claimed is: 

1. A method of performing automatic repeat request (ARQ) 

in a wireless communication system, the method performed 

by a receiver and comprising: 

detecting whether at least one data block to be received 

from a transmitter is missed; 

starting a timer when the at least one data block is detected 

as missed; 

stopping the timer when the at least one data block is 

received from the transmitter while the timer is running, in order to prevent a triggering of a status report before 

the timer expires; and 

transmitting the status report to the transmitter after the 

timer expires, wherein the status report comprises a 

positive acknowledgement indicating receipt of at least one received data block. 

2. The method of claim 1, wherein the at least one data 

block is detected as missed when a sequence number (SN) of 

a currently received data block is larger than a SN of a previ 

ously received data block. 

3. The method of claim 1, wherein the at least one data 

block is detected as missed when a sequence number (SN) 

following a SN of a data block with a highest SN among 

received data blocks is larger than a lowest SN of the at least one data block to be received. 

4. The method of claim 1, wherein the at least one data 

block is detected as missed when a sequence number (SN) 

following a SN of a data block with a highest SN among 

received data blocks is larger than a SN following a last 

in-sequence received data block. 

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US 7,869,396 B2 

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5. The method of claim 1, wherein the timer is stopped when a sequence number (SN) following a SN of a data block 

with a highest SN among received data blocks when the timer 

was started is the same as a SN following the last in-sequence 

received data block. 

6. The method of claim 1, wherein the at least one data 

block comprises a Radio Link Control (RLC) Protocol Data 

Unit (PDU). 

7. The method of claim 1, wherein the status report further 

comprises a negative acknowledgement indicating a 

sequence number (SN) of the at least one data block detected as missed. 

8. A receiver for performing automatic repeat request 

(ARO) in a wireless communication system, the receiver 

comprising a Radio Link Control (RLC) entity, wherein the 

RLC entity is configured to: 

detect whether at least one data block to be received from 

a transmitter is missed; 

start a timer when the at least one data block is detected as 

missed; 

5 

10 

15 

18 

stop the timer when the at least one data block is received 

from the transmitter while the timer is running, in order 

to prevent a triggering of a status report before the timer 

expires; and 

transmit the status report to the transmitter after the timer 

expires, wherein the status report comprises a positive acknowledgement indicating receipt of at least one 

received data block. 

9. The receiver of claim 8, wherein the at least one data 

block is detected as missed when a sequence number (SN) 

following a SN of a data block with a highest SN among 

received data blocks is larger than a SN following a last 

in-sequence received data block. 

10. The receiver of claim 8, wherein the timer is stopped 

when a sequence number (SN) following a SN of a data block 

with a highest SN among received data blocks when the timer 

was started is the same as a SN following the last in-sequence 

received data block. 

Case 1:20-cv-22051-JEM Document 1-26 Entered on FLSD Docket 05/15/2020 Page 21 of 21