KR20100078134A - Method of confirming paging information in wireless communication system - Google Patents

Abstract

PURPOSE: A method of confirming paging information in a wireless communication system is provided to reduce the amount of wireless resources necessary for transmitting a terminal identifier, thereby increasing a data rate. CONSTITUTION: UE receives a paging message(S410). The paging message includes a multiplexed bit array. The UE determines bit positions to check according to a UE ID(S420). Based on the bit positions, the UE confirms the multiplexed bit array(S430). The UE performs production and transmission of the multiplexed bit array. A base station receives the multiplexed bit array. The base station extracts multiplexed information from the multiplexed bit array.

Description

How to check paging information in wireless communication system {METHOD OF CONFIRMING PAGING INFORMATION IN WIRELESS COMMUNICATION SYSTEM}

The present invention relates to wireless communication, and more particularly, to a method for exchanging paging information in a wireless communication system.

Wireless communication systems are widely deployed to provide various kinds of communication services such as voice and data. In general, a wireless communication system is a multiple access system capable of supporting communication with multiple users by sharing available system resources (bandwidth, transmission power, etc.). Examples of multiple access systems include code division multiple access (CDMA) systems, frequency division multiple access (FDMA) systems, time division multiple access (TDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, and single carrier frequency (SC-FDMA). division multiple access) system.

In a wireless communication system, generally, one base station provides a service to a plurality of terminals. The base station schedules user data for a plurality of terminals, and transmits control information including scheduling information for the user data together with the user data. In general, a channel carrying the control information is called a control channel, and a channel carrying user data is called a data channel. The terminal monitors the control channel to find its control information, and processes its data when the control information is successfully received.

Identifiers are often used for the terminal to transmit and receive data over a control channel or data channel. For example, the base station includes a terminal identifier in a message and transmits the message. After receiving the message, the base station checks whether the terminal is own data through the terminal identifier included in the message.

Since the terminal identifier is determined according to cell capacity or system capacity, the terminal identifier is large. For example, a Cell-Radio Network Temporary Identity (C-RNTI), which is an intra-cell terminal identifier used in a 3rd Generation Partnership Project (3GPP), has a size of 16 bits.

If the terminal identifier is included in all messages, the size of the message increases. In addition, the capacity to send information bits within the same radio resource is reduced.

There is a need for a method that can efficiently exchange terminal identifiers.

An object of the present invention is to provide a paging information checking method for reducing the amount of radio resources used.

Another object of the present invention is to provide a paging message transmission method for reducing the amount of radio resources required for transmission.

In one aspect, a method of checking paging information in a wireless communication system includes receiving a paging message including a multiplexed bitstream, determining a plurality of bit positions to verify in the multiplexed bitstream, and based on the plurality of bit positions And determining whether paging information is included in the paging message from the multiplexed bit string.

In another aspect, a method of transmitting a paging message in a wireless communication system includes generating a multiplexed bit string mapped from a plurality of terminal identifiers, and transmitting a paging message including the multiplexed bit string.

The amount of radio resources required for transmission of the terminal identifier can be reduced. Therefore, the data rate can be increased and the radio resource can be efficiently used.

The following techniques include code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), orthogonal frequency division multiple access (OFDMA), single carrier frequency division multiple access (SC-FDMA), and the like. It can be used in various wireless communication systems. CDMA may be implemented with a radio technology such as Universal Terrestrial Radio Access (UTRA) or CDMA2000. TDMA may be implemented with wireless technologies such as Global System for Mobile communications (GSM) / General Packet Radio Service (GPRS) / Enhanced Data Rates for GSM Evolution (EDGE). OFDMA may be implemented in a wireless technology such as IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802-20, Evolved UTRA (E-UTRA). UTRA is part of the Universal Mobile Telecommunications System (UMTS). 3rd Generation Partnership Project (3GPP) long term evolution (LTE) is part of an Evolved UMTS (E-UMTS) using E-UTRA, and employs OFDMA in downlink and SC-FDMA in uplink. LTE-Advanced (LTE-A) is an evolution of LTE.

For clarity, the following description focuses on 3GPP LTE / LTE-A, but the technical spirit of the present invention is not limited thereto.

1 shows a wireless communication system.

Referring to FIG. 1, the wireless communication system 10 includes at least one base station 11 (BS). Each base station 11 provides a communication service for a particular geographic area (generally called a cell) 15a, 15b, 15c. The cell may again be divided into multiple regions (referred to as sectors). The UE 12 may be fixed or mobile, and may include a mobile station (MS), a user terminal (UT), a subscriber station (SS), a wireless device, and a personal digital assistant (PDA). , Wireless modem, handheld device, or other terms. The base station 11 generally refers to a fixed station communicating with the terminal 12, and may be referred to as other terms such as an evolved-NodeB (eNB), a base transceiver system (BTS), an access point, and the like. have.

Hereinafter, downlink means communication from the base station to the terminal, and uplink means communication from the terminal to the base station. In downlink, a transmitter may be part of a base station, and a receiver may be part of a terminal. In uplink, a transmitter may be part of a terminal, and a receiver may be part of a base station.

2 shows a structure of a radio frame in 3GPP LTE.

Referring to FIG. 2, a radio frame consists of 10 subframes, and one subframe consists of two slots. The time it takes for one subframe to be transmitted is called a transmission time interval (TTI). For example, one subframe may have a length of 1 ms and one slot may have a length of 0.5 ms.

One slot includes a plurality of orthogonal frequency division multiplexing (OFDM) symbols in the time domain, and includes a plurality of resource blocks (RBs) in the frequency domain. The OFDM symbol is used to represent one symbol period since 3GPP LTE uses OFDMA in downlink, and may be referred to as an SC-FDMA symbol or a symbol period depending on a system. The RB includes a plurality of consecutive subcarriers in one slot in resource allocation units.

The structure of the radio frame is only an example, and the number of subframes included in the radio frame or the number of slots included in the subframe and the number of OFDM symbols included in the slot may be variously changed.

3 is an exemplary diagram illustrating a resource grid for one downlink slot.

Referring to FIG. 3, the downlink slot includes a plurality of OFDM symbols in a time domain. Here, one downlink slot includes 7 OFDMA symbols and one resource block includes 12 subcarriers in a frequency domain, but is not limited thereto.

Each element on the resource grid is called a resource element, and one resource block includes 12 × 7 resource elements. The number N ^DL of resource blocks included in the downlink slot depends on the downlink transmission bandwidth set in the cell.

4 shows a structure of a subframe.

Referring to FIG. 4, the subframe includes two slots. The maximum 3 OFDM symbols of the first slot in the subframe are the control region to which the PDCCH is allocated, and the remaining OFDM symbols are the data region to which the PDSCH is allocated. The PCFICH transmitted in the first OFDM symbol of a subframe carries information about the number of OFDM symbols used for transmission of PDCCHs in the subframe.

PDCCH includes resource allocation and transmission format of DL-SCH, paging information on PCH, system information on DL-SCH, resource allocation of higher layer control messages such as random access response transmitted on PDSCH, individual UEs in any UE group. It can carry a set of transmit power control commands for, enable VoIP, and so on. A plurality of PDCCHs may be transmitted in the control region, and the terminal monitors the plurality of PDCCHs. The PDCCH is transmitted on an aggregation of one or several consecutive control channel elements (CCEs). CCE is a logical allocation unit used to provide a PDCCH with a coding rate according to a state of a radio channel. The CCE corresponds to a plurality of resource element groups. The format of the PDCCH and the number of bits of the PDCCH are determined according to the correlation between the number of CCEs and the coding rate provided by the CCEs.

Control information transmitted through the PDCCH is called downlink control information (DCI). DCI transmits uplink or downlink scheduling information or an uplink transmission power control command for certain UE groups. DCI is DCI format 0 for transmission of uplink shared channel (UL-SCH) allocation, DCI format 1 for transmission of DL-SCH allocation for single input multiple output (SIMO) operation, DL-SCH allocation for SIMO operation. DCI format 1A for simple transmission or PDSCH transmission of system information or random access response, DCI format 1B for multiple input multiple output (MIMO) rank 1 transmission based on simple resource allocation, PDSCH transmission or randomization of system information DCI format 1C for access response, DCI format 2 for transmission of DL-SCH allocation for MIMO operation, and DCI formats 3 and 3A for transmission of a transmission power control (TPC) command for an uplink channel may be classified. .

5 is a flowchart showing the configuration of a PDCCH.

Referring to FIG. 5, in step S110, the base station determines the PDCCH format according to the DCI to be sent to the terminal and attaches a CRC (Cyclic Redundancy Check) to the control information. The CRC is masked with a unique identifier (referred to as RNTI (Radio Network Temporary Identifier)) according to the owner or purpose of the PDCCH. If the PDCCH is for a specific terminal, a unique identifier of the terminal, for example, a C-RNTI (Cell-RNTI) may be masked to the CRC. Alternatively, if the PDCCH is for a paging message, a paging indication identifier, for example, P-RNTI (P-RNTI), may be masked to the CRC. If it is a PDCCH for system information, a system information identifier and a system information-RNTI (SI-RNTI) may be masked to the CRC. A random access-RNTI (RA-RNTI) may be masked to the CRC to indicate a random access response that is a response to the transmission of the random access preamble of the UE. The following table shows examples of identifiers masked on the PDCCH.

Type Identifier Description UE-specific C-RNTI used for the UE corresponding to the C-RNTI
Common P-RNTI used for paging message SI-RNTI used for system information (It could be differentiated according to the type of system information.) RA-RNTI used for random access response (It could be differentiated according to subframe or PRACH slot index for UE PRACH transmission.) TPC-RNTI used for uplink transmit power control command. (It could be differentiated according to the index of UE TPC group.)

If the C-RNTI is used, the PDCCH carries control information for the corresponding specific terminal. If another RNTI is used, the PDCCH carries common control information received by all or a plurality of terminals in the cell.

In step S120, the DCI to which the CRC is added is subjected to channel coding to generate coded data. In step S130, rate mathing is performed according to the number of CCEs allocated to the PDCCH format. In step S140, the coded data is modulated to generate modulation symbols. In step S150, modulation symbols are mapped to physical resource elements.

A plurality of PDCCHs may be transmitted in one subframe. The UE monitors the plurality of PDCCHs in every subframe. Here, monitoring means that the UE attempts to decode each of the PDCCHs according to the monitored PDCCH format. In the control region allocated in the subframe, the base station does not provide the UE with information about where the corresponding PDCCH is. The UE finds its own PDCCH by monitoring a set of PDCCH candidates in a subframe. This is called blind decoding. For example, if the CRC error is not detected by demasking its C-RNTI in the corresponding PDCCH, the UE detects the PDCCH having its DCI.

We now describe the sending and receiving of paging messages. The paging message is a message indicating the arrival of the downlink data, the base station arbitrarily sent to the terminal. The terminal receiving the paging message confirms that there is downlink data to be transmitted to the terminal, and attempts to monitor the downlink channel. If the paging message is not received, the terminal enters a sleep mode at predetermined intervals. The sleep mode is a mode in which the UE stops monitoring the downlink channel in order to minimize battery consumption. The period in which the terminal is in the sleep mode is called a DRX (discontinuous) cycle, and the period in which the terminal wakes up for monitoring the downlink channel is called a non-DRX cycle.

6 illustrates an example of receiving a paging message.

Referring to FIG. 6, the UE does not receive any subframe (or PDCCH) in the DRX cycle. This is called a DRX subframe. In the non-DRX cycle, the UE monitors the PDCCH every subframe (this is called a non-DRX subframe). If a CRC error is not detected as a result of decoding using the P-RNTI in the PDCCH candidate, the DCI of the corresponding PDCCH is read. The terminal receives a paging message on the PDSCH using the downlink resource allocation included in the DCI. This is said to receive a paging message on the PDSCH indicated by the PDCCH indicated by the P-RNTI.

The P-RNTI is not specific to each terminal but is a common RNTI. That is, all the terminals receive the PDCCCH using the same P-RNTI, and whether or not it is its paging information is distinguished using the UE identifier in the paging message.

7 shows an example of information included in a paging message. The paging message includes UE IDs (UE ID1, UE ID2, ...) that will receive the messaging message and messaging information for each terminal.

If the UE IDs of all terminals to receive the paging message are included in the messaging message, the size of the paging message may be too large. In general, since the UE ID has a size of several tens of bits, excessive downlink resources may be allocated to a paging message when paging is simultaneously attempted to several terminals. Moreover, in order to reduce the time delay of paging, since the paging message is generally transmitted simultaneously in multiple cells, the consumption of downlink resources can be further increased.

8 is a block diagram illustrating an information multiplexing method according to an embodiment of the present invention.

Referring to FIG. 8, in step S310, a set S = {s ₁ , s ₂ ,..., S _t } and a multiplexed bit array v are determined. Each element s _j (1 ≦ _j ≦ t) of the set S is composed of n bits, and the multiplexed bit string v is composed of m bits. The number of bits m of the multiplexed bit string may be smaller than the number of bits n of the element s _j (that is, m <n). All bits of the multiplex bit string v are initialized to zero.

In steps S320 to S350, for each element s _j , the bit corresponding to the bit position indicated by the hash function h _i (s _j ) (1 ≦ _i ≦ k) among the bits belonging to the multiplexed bit string v Set to 1. The hash function h _i (s _j ) is a function that maps to a value of the set {1, ..., m} for a given s _j . If the corresponding bit is already set to 1, leave it as is. If there are k hash functions, up to k bits can be set to 1 for one element s _j .

In steps S360 and S370, the above steps S320 to S350 are repeated for all the elements belonging to the set S. Accordingly, a multiplexed bit string mapped to all elements belonging to the set S can be obtained.

To determine whether a specific element x belongs to the set S, it is necessary to check whether bits of the multiplexed bit string corresponding to all h _i (x) are set to 1. If no bit is set to 1, x does not belong to set S.

9 shows an example of applying information multiplexing to a UE ID. Set S = {UE ID1, UE ID2} and m = 10. This may assume that one paging message includes paging information of a first terminal having UE ID1 and paging information of a second terminal having UE ID2. The multiplexing bit string is initialized to v = '0000000000'. Assume that the number of hash functions k = 3. When h ₁ (UE ID1) = 1, h ₂ (UE ID1) = 4, and h ₃ (UE ID1) = 9 with respect to UE ID1, the multiplexed bit string v = '1001000010'. Then, it is recorded for the _{ID2 h 1 (UE ID2) =} 3, h 2 (UE ID2) = 4, h 3 (UE ID2) to said = 8, multiplexed bit stream v = '1011000110'. As a result, the multiplexed bit string v = '1011000110', which is not UE ID1 and UE ID2, is included in the paging message and transmitted.

The base station may include the multiplexed bit string obtained through the above process in the paging message as it is, or may include the bit string whose length is reduced through a predetermined compression process in the paging message. In this case, the terminal first restores the original multiplexed bit string from the compressed bit string in the received paging message, and then checks the information according to the following procedure.

According to the above method, the overhead due to the transmission of the UE ID can be reduced. For example, if the number of bits of the UE ID is 16, 32 bits are required for transmitting two UE IDs, but the multiplexing bit string may be 10 bits. Therefore, the size of the paging message can be reduced, and the amount of radio resources required for transmitting the paging message can be reduced. Thus, the efficiency of radio resource usage in the system can be improved.

10 is a flowchart illustrating an information verification method using a multiplexed bit string. In step S410, the terminal receives a paging message including a multiplexed bit string. For example, assume that the multiplexed bit string v = '1011000110' is received. In step S420, the terminal determines bit positions to check according to its UE ID. If the UE knows the hash function h _i (s _j ) (1≤i≤k) and uses UE ID1 used in the embodiment of FIG. 9 as the UE ID, the bit positions are {1, 4, 9}. . In step S430, the terminal checks the multiplexed bit string based on the bit positions. In the multiplexing bit string v = '1011000110', since the 1st, 4th, and 9th bits are set to 1, the terminal may confirm that the received paging message includes its paging information. In contrast, if the bit positions to be checked are {1,2,3}, since the second bit is not set to 1 in the multiplexed bit string v = '1011000110', the terminal receives the paging message including its paging information. You can see that it does not.

The above embodiments exemplarily describe the technical idea of the present invention with respect to multiplexing of UE IDs, but are not limited thereto. For example, it may be applied to transmission of a channel quality indicator (CQI), a precoding matrix indicator (PMI), and a rank indicator (RI). Various downlink information and / or uplink information having n bits may be multiplexed into a bit string having m bits (m <n) and transmitted.

Although the above embodiments describe the transmission of a paging message, this is merely an example. The multiplexed bit string indicating the multiplexed information may be included and used in various downlink messages.

In addition, the multiplexed bit string may be used for uplink transmission as well as downlink transmission. The terminal generates and transmits the multiplexed bit string, and the base station may receive the multiplexed bit string and extract the multiplexed information from the multiplexed bit string.

There is no limitation on how to determine the number m of multiplexed bit strings and / or the number k of hash functions. The number m of multiplexed bit strings and / or the number k of hash functions may be specified in advance between the terminal and the base station, or the base station may inform the terminal. The number m of multiplexed bit strings and / or the number k of hash functions may be constant values, and may vary with time or with specific conditions.

The hash function can be defined in the form of a function or in the form of a table. Information about the hash function may be previously specified between the terminal and the base station, or the base station may inform the terminal.

Although the multiplex bit string is initialized to '0' and '1' is set, this is not a limitation. In the opposite case, the multiplexed bit string is initialized to '1' and '0' may be set.

11 is a block diagram illustrating a transmitter and a receiver according to an embodiment of the present invention. In downlink, a transmitter may be part of a base station, and a receiver may be part of a terminal. In uplink, a transmitter may be part of a terminal, and a receiver may be part of a base station.

Referring to FIG. 11, the transmitter 600 includes a processor 610, a memory 620, and a transmit circuitry 630. Processor 610 generates a multiplexed bit string v from the set S of transmitted information. The memory 620 stores information about a hash function required for generating the multiplexed bit string v. The transmission circuit 630 transmits the multiplexed bit string v through the transmission antenna 690.

The receiver 700 includes a processor 710, a memory 720, and a receive circuitry 730. The receiving circuit 730 receives the multiplexed bit string v through the receiving antenna 790. The processor 710 extracts information from the multiplexed bit string v based on the bit positions. Memory 720 stores information about hash functions for determining bit positions.

The present invention may be implemented in hardware, software, or a combination thereof. (DSP), a programmable logic device (PLD), a field programmable gate array (FPGA), a processor, a controller, a microprocessor, and the like, which are designed to perform the above- , Other electronic units, or a combination thereof. In the software implementation, the module may be implemented as a module that performs the above-described function. The software may be stored in a memory unit and executed by a processor. The memory unit or processor may employ various means well known to those skilled in the art.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made therein without departing from the spirit and scope of the invention. You will understand. Therefore, the present invention is not limited to the above-described embodiment, and the present invention will include all embodiments within the scope of the following claims.

1 shows a wireless communication system.

2 shows a structure of a radio frame in 3GPP LTE.

3 is an exemplary diagram illustrating a resource grid for one downlink slot.

4 shows a structure of a subframe.

5 is a flowchart showing the configuration of a PDCCH.

6 illustrates an example of receiving a paging message.

7 shows an example of information included in a paging message.

8 is a block diagram illustrating an information multiplexing method according to an embodiment of the present invention.

9 shows an example of applying information multiplexing to a UE ID.

10 is a flowchart illustrating an information verification method using a multiplexed bit string.

11 is a block diagram illustrating a transmitter and a receiver according to an embodiment of the present invention.

Claims (7)

In the method of checking paging information in a wireless communication system, Receiving a paging message comprising a multiplexed bit string; Determining a plurality of bit positions to check in the multiplexed bit stream; And Determining whether paging information is included in the paging message from the multiplexed bit stream based on the plurality of bit positions. The method of claim 1, Wherein the plurality of bit positions are obtained from a plurality of hash functions, each hash function mapping a terminal identifier to a bit position in the multiplexed bit string. The method of claim 1, And when all bits corresponding to the plurality of bit positions are set to 1 in the multiplexed bit string, determining that the paging message includes its paging information. In the method of transmitting a paging message in a wireless communication system, Generating a multiplexed bit string mapped from the plurality of terminal identifiers; And Transmitting a paging message comprising the multiplexed bit string. The method of claim 4, wherein And the number n of terminals of the terminal identifier is larger than the number m of bits of the multiplexed bit string. The method of claim 4, wherein The multiplexed bit string is generated by setting a bit corresponding to a plurality of bit positions mapped from respective terminal identifiers to one. The method of claim 6, And wherein the plurality of bit positions are obtained from a plurality of hash functions that map a terminal identifier to bit positions in the multiplexed bit string.

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