JP2007243405A - Wireless buffer device, wireless communication device, and wireless buffer control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily allocate wireless resources for each wireless frame, based on QoS which a user requires. <P>SOLUTION: The wireless buffer device comprises: a packet buffer 11 in which packets for wireless transmission is stored; a transmission limit deciding part 14 which decides transmission limit in unit of wireless frame of packets based on QoS required by a user; a transmission packet information table 13 which stores transmission limit of each packet; and a control packet 12 which outputs a packet from the packet buffer 11, based on the transmission limit. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a wireless buffer device, a wireless communication device, and a wireless buffer control method.

  As a next-generation wireless access system, the IEEE (Institute of Electrical and Electronic Engineers) standard “IEEE802.16” is known to realize high-speed and wideband transmission (see, for example, Non-Patent Document 1). In the IEEE 802.16 standard, an orthogonal frequency division multiple access (OFDMA) system is adopted as one of transmission systems. The OFDMA system is one of multicarrier transmission systems that perform communication using a wideband signal composed of a plurality of subcarriers whose frequencies are orthogonal to each other. Realize multiple access between one base station and multiple users.

  As a similar multi-carrier transmission method, the Orthogonal Frequency Division Multiplexing (OFDM) method is known. The OFDM method occupies a wide frequency band by one user, whereas the OFDMA method In general, since the frequency with a good environment varies depending on the user, a subcarrier with a good environment is selected and communicated for each user.

  The IEEE 802.16 standard defines a QoS (Quality of Service) control mechanism. In QoS control, radio resources such as a frequency band and a time slot for a specific communication are reserved, and a communication speed, a delay amount until arrival of a packet, a jitter of arrival of a packet, and the like are guaranteed. In the IEEE 802.16 standard, a control mechanism for guaranteeing a scale for achieving such communication quality is specified, but a QoS control method is not specified.

  FIG. 7 is a diagram illustrating a conventional configuration example of a radio frame (hereinafter referred to as “downlink frame”) 100 of an OFDMA downlink (link from a base station to a terminal station). The downlink frame 100 in FIG. 7 conforms to the IEEE802.16 standard. In FIG. 7, a downlink frame 100 includes a plurality of OFDMA symbols and a plurality of subcarriers. The OFDMA symbols are multiplexed in the time direction in a downlink subframe duration. Also, frequency multiplexing for the number of subcarriers per OFDMA symbol is possible. In the OFDMA system, arrangement information indicating which subcarrier of which OFDMA symbol the packet addressed to each user is arranged is determined for each downlink frame 100. The transmitter of the base station determines radio resources to be used for downlink packet transmission according to the arrangement information. Also, the receiver of each terminal station receives a packet addressed to itself from the downlink frame according to the arrangement information.

  As shown in FIG. 7, “Preamble”, “FCH”, “DL-MAP”, and “DL burst” are arranged in the downlink frame 100. “Preamble” is a portion for storing a known signal. “FCH” is a part for storing a control channel signal. “DL-MAP” is a part for storing arrangement information. “DL burst” is a part for storing packets. The location of “Preamble”, “FCH”, and “DL-MAP” is fixed. With regard to “DL burst”, the number and location can be arbitrarily determined within the limits defined by the IEEE 802.16 standard. In the example of FIG. 7, six “burst” for downlink, that is, “DL burst” are provided. The installation method complies with the IEEE 802.16 standard.

The IEEE 802.16 standard defines how to assign OFDMA symbols and subcarriers in the downlink frame 100, that is, how to provide "DL burst". According to the regulation, as in the frame configuration shown in FIG. 7, one “burst” secures rectangular resources in the time direction (OFDMA symbol direction) and frequency direction (subcarrier direction), Must be assigned data. The “burst” is defined as follows.
(1) “burst” is a data sequence in which packets are connected. In one “burst”, the same modulation scheme and the same error correction coding rate are applied and transmitted.
(2) Within one “burst”, packets addressed to different users may be mixed.
(3) The maximum number of “burst” is limited.
IEEE Std 802.16-2004, “Air Interface for Fixed Broadband Wireless Access Systems,” 2004.

  As described above, according to the IEEE 802.16 standard, there are various restrictions in determining which subcarrier of which OFDMA symbol a packet addressed to each user is placed in an OFDMA downlink frame. For this reason, conventionally, complex control is required to configure the downlink frame under the restriction, and further, the packet arrangement on the downlink frame is determined in consideration of the QoS requested by the user. Was not easy.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a radio buffer device and a radio communication device that can facilitate radio resource allocation for each radio frame based on QoS requested by a user. And providing a wireless buffer control method.

  In order to solve the above problems, a wireless buffer control device according to the present invention determines a transmission time limit for each packet of a wireless frame based on packet buffer means for storing a packet to be wirelessly transmitted and QoS requested by a user. And a transmission packet information table for storing a transmission time limit for each packet, and a control means for outputting a packet from the packet buffer means based on the transmission time limit.

  In the wireless buffer control device according to the present invention, the transmission time limit determining means updates the transmission time limit for each wireless frame.

  In the wireless buffer control device according to the present invention, the transmission packet information table stores transmission packet information in the order from the shortest transmission deadline.

  The wireless buffer control device according to the present invention is characterized by comprising transmission packet information output means for outputting transmission packet information including the transmission deadline for each packet for each wireless frame.

  In the wireless buffer control device according to the present invention, the transmission packet information is stored in the order of shortest transmission deadline.

  In the radio buffer control device according to the present invention, the packet buffer means stores the packet in units of radio transmission blocks, and the radio buffer device manages the packets in units of radio transmission blocks. To do.

  A wireless communication device according to the present invention includes the above-described wireless buffer device.

  The wireless buffer control method according to the present invention is a packet buffer control method for storing a packet to be transmitted wirelessly, and determines a transmission time limit for each wireless frame of the packet based on QoS requested by a user; The method includes storing a transmission deadline for each packet in a transmission packet information table, and outputting a packet from the packet buffer based on the transmission deadline.

  According to the present invention, packets are output from the radio buffer with a radio frame-by-radio transmission period based on the QoS requested by the user. Therefore, when radio resources are allocated for each radio frame, the QoS required by the user is specially requested. There is no need to consider. This makes it possible to easily perform radio resource allocation for each radio frame based on the QoS requested by the user.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing a configuration of a wireless buffer device 1 according to an embodiment of the present invention. The wireless buffer device 1 of FIG. 1 is provided in, for example, an OFDMA wireless communication device (such as a base station device).

In FIG. 1, the wireless buffer device 1 includes a packet buffer 11, a control unit 12, a transmission packet information table 13, a transmission time limit determination unit 14, and a transmission packet information output unit 15.
The packet buffer 11 stores a packet to be wirelessly transmitted. The transmission packet output from the packet buffer 11 receives radio resource assignment, is stored in a radio frame, and is transmitted.

  The control unit 12 controls the packet buffer 11 based on the transmission packet information table 13. The transmission packet information table 13 stores information for each transmission packet, such as a transmission time limit.

  The transmission time limit determination unit 14 determines the transmission time limit of the transmission packet based on the QoS information. The transmission deadline is a transmission deadline for each radio frame. In other words, the transmission deadline indicates how many frames the packet should be transmitted within. The transmission time limit determining unit 14 grasps a radio frame section from the radio frame information. The radio frame information is, for example, a timing signal for each radio frame, a radio frame number, or the like. The QoS information represents QoS requested by the user (for example, maximum allowable delay amount, minimum transmission rate, etc.). The transmission time limit determining unit 14 determines how many frames within the transmission packet should be transmitted from the maximum allowable delay amount and the minimum transmission rate indicated by the QoS information.

  In the IEEE 802.16 standard, the QoS levels include voice-enabled real-time service (unsolicited grant service (UGS)), video-enabled real-time service (real-time polling service: rtPS), and non-real-time service (non-real-time polling service: nrtPS) is specified. In these three QoS levels, for example, it is conceivable to set transmission deadlines in the order of UGS, rtPS, nrtPS in ascending order of maximum allowable delay amount. That is, the shortest transmission deadline is set for the UGS with the smallest maximum allowable delay amount, the next shortest transmission deadline is set for the rtPS with the smallest maximum allowable delay amount, and the nrtPS with the largest maximum allowable delay amount For this, the longest transmission deadline may be set.

  The transmission packet information output unit 15 outputs the transmission packet information in the transmission packet information table 13. This transmission packet information can be used for radio resource allocation to the transmission packet.

Next, the operation of the wireless buffer device 1 according to this embodiment will be described.
2 to 5 are explanatory diagrams for explaining the radio buffer control method according to the present embodiment. Note that, here, a case will be described as an example where transmission is performed using a downlink radio frame (downlink frame) applied to an OFDMA-based downlink conforming to the IEEE 802.16 standard.

  In the downlink of the IEEE 802.16 standard, packets arrive at the packet buffer 11 of the base station in data units called “medium access control layer (MAC) SDU (service data unit)”. The base station transmits a MAC SDU unit packet as it is in a “MAC PDU (protocol data unit)”, or further applies one MAC SDU data unit when applying ARQ (automatic repeat request). The MAC PDU is divided into data units “ARQ BLOCK” having a smaller size called “ARQ BLOCK SIZE” and transmitted.

First, the operation of the wireless buffer device 1 will be described with reference to FIG. FIG. 2 shows a case in which a MAC SDU unit packet is directly transmitted as a MAC PDU.
In FIG. 2, a packet buffer 11 stores packets in units of MAC SDUs. The packet buffer 11 is provided for each CID (connection identifier). In the downlink of the IEEE 802.16 standard, an identifier (CID) is assigned for each communication performed by the user. In the example of FIG. 2, a configuration related to the packet buffer 11 for CID “# 0” is shown. The transmission packet information table 13 stores transmission packet information for each MAC SDU. Transmission packet information has the number of bytes and a transmission time limit (Deadline) for each MAC SDU. Since the packet has a variable length, the number of bytes for each MAC SDU is included in the transmission packet information. At this time, the number of bytes of additional information such as the header of the MAC PDU is also included. The transmission deadline “Deadline” indicates the number of frames within which the MAC SDU must be transmitted. For example, regarding “MAC SDU # 0”, the number of bytes is 100 bytes, and it is indicated that it must be transmitted within 10 frames. The control unit 12 outputs the MAC SDU from the packet buffer 11 based on the transmission time limit in the transmission packet information table 13. As the output order, the MAC SDU with a short transmission time limit is output first.

Next, the operation of the wireless buffer device 1 will be described with reference to FIGS. 3 to 5 show a case where ARQ is applied.
3 to 5, the packet buffer 11 stores the MAC SDU divided into ARQ BLOCKs. The packet buffer 11 is provided for each CID. In the example of FIGS. 3 to 5, the configuration related to the packet buffer 11 for CID “# 0” is shown. The transmission packet information table 13 stores transmission packet information for each ARQ BLOCK. The transmission packet information has the number of bytes and a transmission deadline (Deadline) for each ARQ BLOCK. For example, FIG. 3 shows that “ARQ BLOCK # 0” has 100 bytes and must be transmitted within 10 frames. Further, “ARQ BLOCK # 1” is 100 bytes, and it is shown that it must be transmitted within 20 frames. Further, “ARQ BLOCK # 2” indicates that the number of bytes is 50 bytes and must be transmitted within 20 frames.

  “ARQ BLOCK # 1” and “ARQ BLOCK # 2” are obtained by dividing the same MAC SDU, and therefore the transmission deadlines are the same. In addition, when applying ARQ, even if ARQ BLOCK generated from the same MAC SDU can be stored in different MAC PDUs by applying fragmentation, MAC SDU can be stored in ARQ BLOCK. In this case, the number of bytes and the transmission deadline are managed for each ARQ BLOCK.

  The control unit 12 outputs ARQ BLOCK from the packet buffer 11 based on the transmission time limit in the transmission packet information table 13. As the output order, the ARQ BLOCK with a short transmission time limit is output first.

  FIG. 3 shows the state at the nth radio frame, FIG. 4 shows the state at the (n + 1) th radio frame, and FIG. 5 shows the state at the (n + 2) th radio frame. At the time of the nth radio frame shown in FIG. 3, the control unit 12 outputs “ARQ BLOCK # 0” with the shortest transmission time limit. Next, at the (n + 1) th radio frame shown in FIG. 4, the transmission deadline determination unit 14 updates the transmission deadline in the transmission packet information table 13. That is, each transmission time limit is shortened by one frame. At the (n + 1) -th radio frame shown in FIG. 4, the control unit 12 does not output ARQ BLOCK. Next, at the (n + 2) th radio frame shown in FIG. 4, the transmission time limit determining unit 14 shortens and updates each transmission time limit in the transmission packet information table 13 by one frame.

  Note that the update of the transmission deadline for each radio frame is the same when the MAC SDU unit packet shown in FIG.

  The transmission packet information table 13 facilitates output control of the packet buffer 11 by storing transmission packet information in ascending order of transmission deadlines.

  As described above, since the transmission packet is output from the packet buffer 11 with the transmission deadline in units of radio frames based on the QoS requested by the user, the user requests specially when allocating radio resources for each radio frame. There is no need to consider QoS. Thereby, the effect that the radio | wireless resource allocation for every radio | wireless frame based on QoS which a user requests | requires can be performed easily is acquired.

Next, the operation of the transmission packet information output unit 15 will be described with reference to FIG. FIG. 6 is an example of transmission packet information.
The transmission packet information output unit 15 reads the transmission packet information from the transmission packet information table 13 and outputs it.
In FIG. 6, the transmission packets are ranked in the transmission order. The transmission packet information has a CID, the number of bytes, and a transmission time limit (Deadline) for each transmission block (Block = # 1, # 2, # 3,...).

  The transmission block is a transmission unit when transmitting a packet, and is, for example, MAC SDU or ARQ BLOCK. In the downlink of the IEEE 802.16 standard, an identifier (CID) is assigned for each communication performed by the user, and the CID is included in the transmission packet information. Since the packet has a variable length, the number of bytes of the transmission packet is included in the transmission packet information as the number of bytes for each transmission block. The transmission deadline “Deadline” indicates the number of frames within which the packet must be transmitted.

  In FIG. 6, for example, a transmission block “Block = # 1” is a transmission block of a packet of CID “# 0”, the number of bytes of the transmission block is 100 bytes, and the transmission deadline “Deadline = 1” is within one frame. It is.

  As shown in FIG. 6, the transmission packet information output unit 15 arranges the transmission packet information in order from the earliest transmission time limit. The transmission packet information output unit 15 outputs transmission packet information for each radio frame.

  The transmission packet information output from the wireless buffer device 1 can be used for radio resource allocation for the transmission packet. For example, in the downlink frame of the OFDMA system compliant with the IEEE802.16 standard, the arrangement information indicating which subcarrier of which OFDMA symbol the packet addressed to each user is arranged on the basis of transmission packet information for each downlink frame Can be determined. This makes it possible to perform more detailed radio resource allocation corresponding to the QoS level requested by the user for each downlink frame.

  As described above, according to the present embodiment, for example, when the downlink radio frame (downlink frame) is configured by applying to the downlink of the OFDMA system compliant with the IEEE802.16 standard, the Therefore, it is not necessary to consider the QoS requested by the user. As a result, in the downlink of the OFDMA system compliant with the IEEE 802.16 standard, radio resource allocation for each downlink frame based on the QoS requested by the user, that is, the packet on the downlink frame based on the QoS requested by the user The special effect that it becomes easy to realize the arrangement is obtained.

The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and includes design changes and the like within a scope not departing from the gist of the present invention.
For example, the present invention is not limited to the IEEE 802.16 standard and can be applied to various wireless communication systems.

It is a block diagram which shows the structure of the radio | wireless buffer apparatus 1 which concerns on one Embodiment of this invention. It is explanatory drawing for demonstrating the radio | wireless buffer control method which concerns on the same embodiment. It is explanatory drawing for demonstrating the radio | wireless buffer control method which concerns on the same embodiment. It is explanatory drawing for demonstrating the radio | wireless buffer control method which concerns on the same embodiment. It is explanatory drawing for demonstrating the radio | wireless buffer control method which concerns on the same embodiment. It is an example of the transmission packet information which concerns on the same embodiment. 1 is a diagram illustrating a conventional configuration example of an OFDMA downlink frame 100. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Wireless buffer apparatus, 11 ... Packet buffer, 12 ... Control part, 13 ... Transmission packet information table, 14 ... Transmission deadline determination part, 15 ... Transmission packet information output part

Claims (8)

Packet buffer means for storing packets to be transmitted wirelessly;
A transmission time limit determining means for determining a transmission time limit for each radio frame of the packet based on QoS requested by the user;
A transmission packet information table for storing a transmission time limit for each packet;
Control means for outputting a packet from the packet buffer means based on the transmission deadline;
A wireless buffer device comprising:   2. The wireless buffer device according to claim 1, wherein the transmission time limit determining unit updates the transmission time limit for each wireless frame.   The wireless buffer device according to claim 1, wherein the transmission packet information table stores transmission packet information in an order from the shortest transmission deadline.   4. The wireless buffer device according to claim 1, further comprising transmission packet information output means for outputting transmission packet information including a transmission time limit for each packet for each wireless frame.   5. The wireless buffer device according to claim 4, wherein the transmission packet information stores transmission packet information in an order from the shortest transmission deadline. The packet buffer means stores the packet in units of radio transmission blocks,
6. The wireless buffer device according to claim 1, wherein the wireless buffer device manages the packet in units of the wireless transmission block.   A wireless communication device comprising the wireless buffer device according to any one of claims 1 to 6. A method for controlling a packet buffer for storing packets to be transmitted wirelessly,
Determining a transmission time limit for each radio frame of the packet based on QoS requested by the user;
Storing a transmission deadline for each packet in a transmission packet information table;
Outputting a packet from the packet buffer based on the transmission deadline;
A wireless buffer control method comprising:

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