WO2006112293A1

WO2006112293A1 - Radio base station, mobile station, and data transmission method

Info

Publication number: WO2006112293A1
Application number: PCT/JP2006/307571
Authority: WO
Inventors: Atsushi Harada; Nobuhiko Miki; Sadayuki Abeta; Mamoru Sawahashi
Original assignee: Ntt Docomo, Inc.
Priority date: 2005-04-13
Filing date: 2006-04-10
Publication date: 2006-10-26
Also published as: TW200701702A; JP2006295724A; JP4403097B2; TWI313987B

Abstract

A radio base station includes storage means stored with plural PDU formats, division means for selecting the PDU format to be used, from the plural PDU formats thereby to divide the packet data into a predetermined PDU size on the basis of the selected PDU format, and mapping means for mapping at least one divided packet data to a predetermined size.

Description

Specification

Radio base station, mobile station, and data transmission method

Technical field

TECHNICAL FIELD [0001] The present invention relates to a radio base station, a mobile station, and a data transmission method for dividing an IP packet into basic transmission units in a radio section and transmitting the packet.

Background art

[0002] The mapping of IP packets to physical channels will be described with reference to FIG.

[0003] In W-CDMA (Wideband-CDMA), an IP packet is divided into a certain radio size, for example, RLC—PDU (Radio Link Control-Protocol Data Unit) size (IP packet division). A header (HD) and a CRC (Cyclic redundancy check) error detection code are added to each RLC-PDU that has been transmitted, and transmitted according to the transmission rate. HD stores information related to the control signal for split Z assembly of IP packets. In addition, retransmission is performed in units of R LC-PDUs.

[0004] Also, in HSDPA (High-Speed Downlink Packet Access), which is an extension of W-CDMA, a plurality of RLC-PDUs are combined to create a MAC-PDU, and a header, for example, for each created MAC-P DU, SN — HARQ (Sequence Number-Hybrid Automatic Repeat Quest) and CRC error detection code are added (PDU combination).

[0005] Multiple channel-coded MAC—blocks of PDUs are combined, and P adding is added as necessary (block combination), interleaved and mapped to form a radio frame (interleaved Z mapping) ).

[0006] In HSDPA, the modulation scheme and coding rate of a radio channel can be changed from a selected MCS (Modulation and Coding Set) according to a transmission state between a base station and a mobile station. In HSDPA, error detection is performed using a new PDU, that is, a CRC error detection code added to the MAC-PDU, and retransmission control is performed between the base station and the mobile station in units of MAC-PDUs. Is called.

[0007] Further, in IEEE 802.11, which is one of the wireless LAN standards, the wireless size is determined according to the size of the IP packet. For this reason, IP packets are transmitted without being divided. Disclosure of the invention

Problems to be solved by the invention

However, the background art described above has the following problems.

[0009] In W—CDMA and HSDPA, RLC—PDU size and MAC—PDU size are transmitted as a unit, but this size is the same for audio data and image data. There are problems that are not optimized for it.

[0010] Further, in IEEE 802.11, since an IP packet is transmitted without being divided, there is a problem that transmission is not performed in a size suitable for wireless transmission.

Therefore, an object of the present invention is to provide a radio base station, a mobile station, and a data transmission method that perform IP packet mapping suitable for mobile radio.

Means for solving the problem

[0012] In order to solve the above problems, the radio base station of the present invention divides packet data into a plurality of fixed-length PDUs, adds header information to the PDUs, and transmits the PDUs to the radio base stations. Storage means for storing the PDU format, dividing means for selecting the PDU format to be used from a plurality of PDU formats, and dividing the packet data into a predetermined P DU size based on the selected PDU format; Mapping means for mapping at least one divided packet data to a predetermined size.

[0013] With this configuration, an appropriate PDU format can be selected from a plurality of PDU formats, and packet data is divided into PDU sizes and transmitted based on the selected PDU format. it can.

[0014] Also, the mobile station of the present invention divides packet data into a plurality of fixed-length PDUs, adds header information to the PDUs, and transmits the PDUs different from the radio base station. Storage means for storing the PDU format in which the size is set.

[0015] With this configuration, packet data can be divided and transmitted to a PDU size different from that of the radio base station.

[0016] In addition, the data transmission method according to the present invention uses a plurality of PDU formats in a data transmission method in which packet data is divided into a plurality of fixed-length PDUs and header information is added to the PDUs. Select the PDU format and the selected P Based on the DU format, the method includes a step of dividing packet data into a predetermined PDU size and a step of mapping at least one divided packet data into a predetermined size.

[0017] By doing so, an appropriate PDU format can be selected from a plurality of PDU formats, and packet data can be divided into PDU sizes based on the selected PDU format and transmitted.

The invention's effect

[0018] According to the embodiment of the present invention, it is possible to realize a radio base station, a mobile station, and a data transmission method that perform IP packet mapping suitable for mobile radio.

Brief Description of Drawings

FIG. 1 is an explanatory diagram showing mapping of IP packets to physical channels.

FIG. 2 is a block diagram showing a mobile station and a radio base station according to an embodiment of the present invention.

FIG. 3 is an explanatory diagram showing a configuration of a PDU.

FIG. 4A is an explanatory diagram showing the structure of a PDU.

FIG. 4B is an explanatory diagram showing the configuration of the PDU.

FIG. 4C is an explanatory diagram showing the configuration of the PDU.

FIG. 4D is an explanatory diagram showing the configuration of the PDU.

FIG. 5A is an explanatory diagram showing a PDU format that is useful in an embodiment of the present invention.

FIG. 5B is an explanatory diagram showing a PDU format that is useful in an embodiment of the present invention.

FIG. 6 is an explanatory diagram showing mapping to physical channels according to an embodiment of the present invention.

FIG. 7 is an explanatory diagram showing mapping to physical channels according to an embodiment of the present invention.

FIG. 8 is an explanatory diagram showing mapping to physical channels according to an embodiment of the present invention.

FIG. 9 is an explanatory diagram showing mapping to physical channels according to an embodiment of the present invention.

FIG. 10 is an explanatory diagram showing mapping to physical channels according to an embodiment of the present invention.

FIG. 11 is a flowchart showing the operation of the radio base station according to the embodiment of the present invention. Explanation of symbols

[0020] 100 radio base station

200 mobile stations BEST MODE FOR CARRYING OUT THE INVENTION

Next, embodiments of the present invention will be described with reference to the drawings.

In all the drawings for explaining the embodiments, the same reference numerals are used for those having the same function, and repeated explanation is omitted.

A mobile communication system according to an embodiment of the present invention will be described with reference to FIG.

A mobile communication system according to the present embodiment includes a radio base station 100 and a mobile station 200 that can perform radio communication with the radio base station 100 and includes a storage unit 201.

Radio base station 100 includes control unit 101 and storage unit 102 connected to control unit 101. The control unit 101 includes a dividing unit 103 connected to the storage unit 102, a combining unit 104 connected to the dividing unit 103, a channel code unit 105 connected to the combining unit 104, and a channel code unit 1 includes a mapping unit 106 connected to 05 and a retransmission control unit 107 connected to mapping unit 106.

[0025] The IP packet is divided into a predetermined PDU size by the dividing unit 103, HD and CRC are attached to each divided RLC-PDU, and input to the combining unit 104. In this case, the dividing unit 103 divides the IP packet based on the PDU format stored in the storage unit 102.

For example, as shown in FIG. 3, an IP packet is composed of a header (HD) part and a payload part.

[0027] The header part is composed of a Sequence Number (hereinafter referred to as SN), a Length Indicator (hereinafter referred to as LI), and an Extension bit (hereinafter referred to as E).

[0028] SN stores information used for PDU number and IP packet division Z assembly. In the LI, when a plurality of IP packets exist in the PDU, information indicating the division point is stored. The unit of this dividing point is indicated by, for example, Octet. In the case of Padding, airi “is stored. In E, information indicating whether the next field is LI or Payload is stored. For example,“ 0 ”for Payload,“ 1 ”for LI. 〃 is stored.

[0029] The payload section stores the data body to be transmitted. In HSDPA, by adaptive modulation, transmission data is transmitted at a high rate such as 16QAM (Quadrature Amplitude Modulation) if the communication state is good, and is transmitted at a low rate if the transmission state is bad. In this case, since the code rate and the like differ depending on the modulation method, the amount of data to be stored also differs.

Next, the configuration of the PDU will be described with reference to FIGS. 4A to 4D.

[0031] In a PDU, for example, when there is only one IP packet in the PDU, when there are two IP packets in the PDU, that is, when a PDU is created across two IP packets When there are 3 IP packets in the PDU, that is, when a PDU is created across 3 IP packets, Padding may exist in the PDU.

[0032] When there is only one IP packet in the PDU, as shown in FIG. 4A, the PDU is composed of SN, E in which "0" is stored, and Payload.

[0033] If there are two IP packets, eg, IP # 1 and IP # 2, in the PDU, as shown in Figure 4B, the PDU is SN, E containing 〃1 ", and LI And E in which 〃0 "is stored, Payload (IP # 1), and Payload (IP # 2). LI stores information indicating the dividing point between Payload (IP # 1) and Payload (IP # 2).

[0034] If there are three IP packets in the PDU, for example, IP # 1, IP # 2, and IP # 3, the PDU contains SN and "1" as shown in Figure 4C E, LI # 1, "1" is stored E, LI # 2, 〃0 "is stored E, Payload (IP # 1), Payload (IP # 2), Payload (LI # 1) stores information indicating the dividing point between IP # 1 and IP # 2, and LI # 2 divides between IP # 2 and IP # 3. Information indicating points is stored.

[0035] When Padding is present in the PDU, as shown in Fig. 4D, the PDU is SN, E that stores "1", LI # 1, and E that stores 〃1 " , All "l", E in which 〃0 "is stored, Payload, and Padding. LI # 1 stores information indicating the division point between Payload and Padding.

Next, the PDU format will be described with reference to FIGS. 5A and 5B.

[0037] First, the downlink PDU format will be described with reference to FIG. 5A.

[0038] In the downlink, a plurality of formats, for example, two types of formats are set. For example, Format # 1 is applied when the spreading factor (SF) is 16 or less, and Format # 2 is applied when the spreading factor is 16 or more and 128 or less. These formats are stored in the storage unit 102.

[0039] Each Format will be described. [0040] In Format # 1, PDUsize is 140 octets, SN + E is 2 octets (15 bits + lbit), and LI + E is 2 octets (15 bits + lbit).

[0041] In Format # 2, PDUsize is 14 octets, SN + E is 2 octets (15 bits + lbit), and LI + E is loctet (7 bits + lbit).

[0042] In a mobile communication system, it is necessary to support from low-rate transmission to high-rate transmission.

[0043] For example, when only one PDU format having a small PDU size power S is prepared, even if data can be transmitted at a high rate, header information is added to the data, and transmission efficiency deteriorates. .

[0044] By preparing a plurality of PDU formats in this way, it is possible to change the PDU size according to transmission data, and accordingly, the number and size of headers can be changed. Can be reduced. For example, by selecting Format # 2, it is possible to reduce the amount of LI + E information for one header.

[0045] The dividing unit 103 may select the PDU format to be used from two types of PDU formats based on the data to be transmitted, and based on the required transmission rate or the state of the transmission path. Let's make a selection.

In addition, the storage unit 102 may be provided with a PDU format for each modulation scheme, for example, or may be provided for each MCS (modulation and code key set). When adaptive modulation is performed, the amount of data stored in the PDU varies depending on the modulation rate and other factors. For this reason, a PDU format is prepared for each MCS. Also, a PDU format may be prepared for some MCS depending on the usage status.

Next, the uplink PDU format will be described with reference to FIG. 5B. The storage unit 201 stores, for example, the following PDU format.

[0048] In the uplink format, the PDUsize is 28 octets, and SN + E is 2 octets (15 bits

+ lbit) and LI + E as loctet (7bits + lbit).

[0049] By changing the uplink and downlink PDU sizes in this way, header information can be efficiently reduced.

[0050] For example, when dealing with a plurality of users, since SF becomes a large value, the downlink PD Format # 2 is selected as the U format. When this format # 2 is used for the uplink, since the PDUsize is small, the transmission data is subdivided and the header information is added, resulting in poor transmission efficiency. However, header information can be reduced and transmission efficiency can be improved by changing the uplink and downlink PDU formats and providing a PDU format with a large PDUsize.

[0051] The IP packet is divided by the dividing unit 103 when the size of the IP packet is larger than the wireless size. When the size of the IP packet is smaller than the wireless size, for example, when the size of the IP packet is small, such as multi-level QAM transmission, the IP packet is not divided and a plurality of IP packets are combined.

[0052] The combining unit 104 combines a plurality of input RLC-PDUs, creates MAC-PDUs, adds a header, for example, SN-HARQ and CRC error detection code, to each created MAC-PDU, Input to channel code field 105.

The channel coding unit 105 performs the channel code of the input MAC-PDU with the HD and CRC attached thereto, and inputs the channel code to the mapping unit 106.

[0054] Mapping section 106 maps the MAC-PDU with the channel-coded HD and CRC attached to the interleaver size.

[0055] Here, a method for mapping to a physical channel will be described with reference to FIGS. 6, 7, and 8, the horizontal axis is the time axis, and the vertical axis is the sign axis.

As a mapping method, SS—MC (Single Slot-Multi Code) mapping, which is mapping to the code (code) axis, shown in FIG. 6, and MS—SC, which is mapping to the time axis, shown in FIG. Multi-Slot-Single Code (Multi Slot-Single Code) mapping and MS-MC (Multi Slot-Multi Code) mapping, which is mapping to the code axis and time axis, shown in Fig. 8, will be described separately.

[0057] In addition, as the retransmission unit in each mapping, multiple codes simultaneously (multi-code Z multi slot) (hereinafter, referred to as PP (p _er Packet)), (the smallest unit of physical channel) code unit (hereinafter, PC ( This is divided into two types, called Per Code).

[0058] First, SS-MC will be described with reference to FIG.

[0059] In SS-MC mapping (SS-MCZPP) in which the unit of retransmission is PP, CRC is attached in units of multiple codes, and the retransmission unit (Retrans.unit) is, for example, in units of IP packets. If CRC is attached, it is an IP packet. As for PER (Packet Error Rate), SF is almost saturated at 16 or less, so the coding gain is high and the time interleaving effect is eliminated. The PER characteristic of IP is equivalent to SS-MC mapping where the unit of retransmission is PC. is there. Latency is small. In addition, since one error detection code is added to multiple codes, there is an advantage that ACKZNAC can be reduced compared to the case where an error detection code is added to each code.

[0060] In the SS-MC mapping (SS-MCZPC) in which the retransmission unit is PC, CRC is added in code units, and the retransmission unit is a code channel. As for PER, since SF is almost saturated at 16 or less, the coding gain is high, and the time interleaving effect is absent. The IP PER characteristic is equivalent to SS-MC mapping, which is the unit power PP of retransmission. Also, the delay is small. In addition, since one error detection code is added for each code, there is an advantage that partial retransmission can be performed compared to the case where an error detection code is added to a plurality of codes at once. In addition, when the error correlation between codes is low, there is an advantage that the channel utilization efficiency can be increased by the effect of partial retransmission.

[0061] Next, MS-SC mapping will be described with reference to FIG.

[0062] In MS-SC mapping (MS-SCZPP) in which the unit of retransmission is PP, a CRC is added in units of multiple codes, and the retransmission unit is an IP packet when a CRC is added in units of IP packets. . As for PER, since SF is almost saturated at 16 or less, there is a time interleaving effect that the coding gain is high, and the PER characteristic of IP is inferior to SS-MC. In addition, the delay is large. Further, there is an advantage that no packet assembly is required.

[0063] In MS-SC mapping (MS-SC / PC) in which the retransmission unit is PC, CRC is added in code units, and the retransmission unit is a code channel. As for PER, since SF is almost saturated at 16 or less, the coding gain is high and the time interleaving effect is not good. The IP PER characteristic is bad. Also, the delay is large. In addition, when the error correlation between codes is low, there is an advantage that the channel utilization efficiency can be increased by the effect of partial retransmission.

[0064] Next, MS-MC mapping will be described with reference to FIG.

[0065] In the MS-MC mapping (MS-MCZPP) in which the unit of retransmission is PP, a CRC is added in units of multiple codes. If it is stale, it is an IP packet. Regarding PER, since SF is almost saturated at 16 or less, the coding gain is high and there is a time interleaving effect. IP PER characteristics are inferior to SS-MC. Delay is greater than SS—MC. In addition, there is an advantage that ACKZNAC can be reduced

[0066] Next, in MS-MC mapping (MS-MCZPC), which is a unit power of retransmission, a CRC is added in code units, and the retransmission unit is a code channel. Since PER is almost saturated at SF force S16 or less, the coding gain is high and there is a time interleaving effect. IP PER characteristics are inferior to SS-MC. Delay is greater than SS—MC. In addition, since one error detection code is added to each code, there is an advantage that partial retransmission can be performed compared to the case where an error detection code is added in units of multiple codes.

[0067] Fig. 9 shows a comparison of SS-MC, MS-SC, and MS-MC for mapping to physical channels.

[0068] Regarding the time interleaving effect, the MS-SC mapping in which the retransmission unit is PP is high, followed by the MS-MC mapping in which the retransmission unit power SPP is high. For MS-SC and MS-MC, which are SS-MC and retransmission unit power SPC, there is no time interleaving effect. Regarding the delay, SS—MC power, followed by MS—SC and MS—MC, where the retransmission unit is PC, are small. The amount of control channel signal that is retransmission unit power SPP increases. In addition, the channel utilization efficiency is high for SS-MC with retransmission unit of PC and MS-SC with retransmission unit of PP. As an example of applicable traffic, SS-MC is a multicast type, and MS-SC whose retransmission unit is PP is a multicast type.

[0069] The mapping unit 106 performs mapping by selecting an appropriate mapping method from the above-described mapping methods.

[0070] For example, as shown in FIG. 10, an optimal mapping method may be selected according to the type of traffic.

In the case of the unicast type, the communication form is one-to-one, and it is necessary to be able to retransmit and to have low delay, so SS-MC that is code direction mapping is used. By mapping in the code direction in this way, transmission can be performed with low delay.

[0072] Also, in the case of the multicast type, since the communication form is one-to-many and retransmission is difficult, Packet errors need to be lowered. For this reason, MS-SC, which is mapping in the time direction, is used. By mapping in the time axis direction in this way, packet errors can be reduced using the time interleaving effect.

[0073] The retransmission control section 107 performs retransmission control based on the retransmission unit set in each mapping.

Next, the operation of radio base station 100 will be described with reference to FIG.

[0075] Transmission data is generated (step S1102). Next, for example, the spreading factor is set based on the transmission data and the state of the transmission path (step S 1104), and the PDU format is determined based on the set spreading factor (step S1106).

[0076] The IP packet is divided into a predetermined PDU size based on the determined PDU format (step S 1108), and HD and CRC are added to each divided RLC-PDU (step S1108). S 1110). Multiple RLC-PDUs with HD and CRC attached are combined to create a MAC-PDU (step S1112), and a header and CRC error detection code are added to each created MAC-PDU. (Step SI 114).

[0077] Next, channel coding is performed on the MAC-PDU to which HD and CRC are added (step S1116) and mapped to the interleaver size (step S1118). In this case, an appropriate mapping method is selected and mapping is performed.

In the above-described embodiment, by applying to the power W-CDMA described in the case of performing data transmission by HSDPA, transmission can be performed with a PDU size optimized for transmission data.

Further, by applying this embodiment to a wireless LAN, data transmission can be performed with a size suitable for wireless transmission.

[0080] This international application claims priority based on Japanese Patent Application No. 2005-116108 filed on Apr. 13, 2005. The entire contents of 2005-116108 are incorporated herein by reference. .

Industrial applicability

[0081] The radio base station, mobile station, and data transmission method according to the present invention can be applied to a communication system that transmits IP packets by dividing them into basic transmission units in a radio section.

Claims

The scope of the claims

[1] For a radio base station that divides packet data into a plurality of fixed-length PDUs (Protocol Data Units), adds header information to the PDUs, and transmits:

Storage means for storing multiple PDU formats;

A dividing unit that selects a PDU format to be used from the plurality of PDU formats and divides the packet data into a predetermined PDU size based on the selected PDU format;

Mapping means for mapping at least one divided packet data to a predetermined size;

A radio base station comprising:

[2] In the radio base station according to claim 1:

The radio base station characterized in that the dividing means selects a PDU format to be used from the plurality of PDU formats based on at least one of transmission data, a transmission rate, and a transmission path state.

[3] In the radio base station according to claim 1:

The radio base station characterized in that the division means adds header information corresponding to the selected PDU format to the PDU.

[4] In the radio base station according to claim 1:

The radio base station characterized in that the storage means comprises a PDU format for each modulation scheme or each set of modulation and code.

[5] In the radio base station according to claim 1:

The radio base station characterized in that the mapping means maps a PDU with header information added to at least one of a code axis and a time axis.

[6] In the radio base station according to claim 5:

The radio base station, wherein the mapping means adds an error detection code in units of at least one code.

[7] In the radio base station according to claim 5,

The mapping means performs the mapping process according to the type of traffic. A featured radio base station.

[8] In the radio base station according to claim 5:

Retransmission means for retransmitting at least one code as a unit;

A radio base station comprising:

[9] Divide the packet data into a plurality of fixed-length PDUs (Protocol Data Units), add the header information to the PDU, and send it to the mobile station:

A storage means that stores a PDU format with a PDU size different from that of the radio base station;

A mobile station comprising:

[10] According to a data transmission method in which packet data is divided into a plurality of fixed-length PDUs (Protocol Data Units) and header information is added to the PDUs and transmitted:

Selecting a PDU format to be used from a plurality of PDU formats; dividing the packet data into a predetermined PDU size based on the selected PDU format;

A data transmission method comprising: mapping at least one divided packet data to a predetermined size.