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Patent Application Titled "Mobile Communication System, Control Device, Base Station Device, System Control Method and Device Control Method"...

June 12, 2014



Patent Application Titled "Mobile Communication System, Control Device, Base Station Device, System Control Method and Device Control Method" Published Online

By a News Reporter-Staff News Editor at Politics & Government Week -- According to news reporting originating from Washington, D.C., by VerticalNews journalists, a patent application by the inventors UEDA, Yoshio (Minato-ku, JP); HAYASHI, Sadafuku (Minato-ku, JP), filed on January 24, 2014, was made available online on May 29, 2014.

The assignee for this patent application is Nec Corporation.

Reporters obtained the following quote from the background information supplied by the inventors: "In 3GPP (3.sup.rd Generation Partnership Project), the HSDPA (High Speed Downlink Packet Access) standard for W-CDMA mobile communication has been standardized (see non-patent document 1). In HSDPA, the MAC-hs protocol or MAC-ehs protocol is used for the MAC (Medium Access Control) layer. HSDPA provides packet-based high-speed data communication on a downlink from an RNC (radio network controller) to a UE (user equipment) via a Node-B. In HSDPA data communication, flow control is performed between the RNC (radio network controller) and the Node-B (base station).

"In the flow control, the Node-B notifies the RNC of the data capacity, and the RNC transmits data within the data capacity to the Node-B. Here, the Node-B determines the data capacity, taking into consideration, e.g., the capacity of the radio channel, the product quality report provided by the UE, the priority allocated to the bearer, and the state of the transmission path between the RNC and the Node-B as parameters. Notification of the data capacity is provided via a frame protocol control message called CAPACITY ALLOCATION.

"In the HSDPA data communication, there are three types of cases contemplated for communication modes. Parameters conforming to each case are set for RNCs and Node-Bs.

"FIG. 1 is a chart illustrating an example of parameter settings for the respective cases of HSDPA. Referring to FIG. 1, examples of parameter settings for respective cases 1 to 3 are illustrated. Case 1 has already been defined in 3GPP Release 5 onwards, and cases 2 and 3 are expected to be defined in 3GPP Release 7 onwards.

"In case 1, the size of PDUs (protocol data units) in the RLC (radio link control) layer (hereinafter referred to as 'RLC PDU size' has a fixed length, and for the MAC layer, the MAC-hs protocol is used. A PDU is a unit of a transmit signal in a predetermined protocol. For example, a PDU includes a header according to a predetermined protocol and a payload including data in the protocol.

"In the MAC-hs protocol, neither 64QAM (Quadrature Amplitude Modulation) nor MIMO (Multiple Input Multiple Output) are used.

"In case 2, the RLC PDU size has a fixed length as in case 1, but the MAC-ehs protocol is used for the MAC layer. In the MAC-ehs protocol, 64QAM and MIMO can be used. Also in the MAC-ehs, a transmission method called Improved Layer 2 in Downlink is used.

"64QAM, which is one of digital modulation methods, expresses 64 values through a combination of eight phase types and eight amplitude types. MIMO is a radio communication technique for expanding a data communication band using a plurality of antennas simultaneously. In Improved Layer 2, the MAC-ehs protocol provided in Node-B segments user data. Improved Layer 2 enables more efficient data transfer compared to a transmission method in which user data is divided by a fixed length in an RLC.

"In case 3, the RLC PDU size has a variable length, and for the MAC layer, the MAC-ehs protocol is used. In this case, a Node-B designates a maximum length of the RLC PDU size. An RNC can select an RLC PDU size within a range equal to or less than the maximum length designated by the Node-B. In flow control, the Node-B can control the maximum value of the RLC PDU size.

"In flow control in 3GPP Release 7 into which the MAC-ehs protocol has been introduced, a format called CAPACITY ALLOCATION TYPE 2 is used instead of a format called CAPACITY ALLOCATION TYPE 1 that is used in 3GPP Release 5.

"With a frame in CAPACITY ALLOCATION TYPE 2, a Node B can control the following four elements.

"(1) Maximum MAC-d/c PDU Length (MAC-d PDU length) (2) HS-DSCH Credit (the number of MAC-d PDUs that can be transmitted during an interval of transmission in an HS-DSCH) (3) HS-DSCH Interval (duration in which the number of MAC-d PDUs indicated by the HS-DSCH credit are transmitted) (4) HS-DSCH Repetition Period (repetition count indicating the number of repetitions of the above duration)

"For example, where a radio channel is going into a congestion, the MAC-d/c PDU Length (Maximum MAC-d/c PDU length) may be reduced or the HS-DSCH credit may be reduced in order to suppress the downlink data amount. An HS-DSCH (High-Speed Downlink Shared Channel) is a channel shared by a plurality of HSDPA data communications.

"As described above, in cases 2 and 3, which are to be defined in 3GPP Release 7 onwards, 64QAM and MIMO, which could not used in and before 3GPP Release 6, can be used.

"Between cases 2 and 3 to be defined in 3GPP Release 7 onwards, there is a difference in whether the RLC PDU size has a fixed length or a variable length.

"In case 3, since the RLC PDU size is variable, the maximum value of the RLC PDU size can be changed in a range equal to or less than 1504 octets in flow control. As a result of such flow control, more efficient data communication can be provided according to the changing communication status.

"Meanwhile, case 2 enables use of 64QAM and MIMO while performing flow control using an existing and simple algorithm with the RLC PDU size fixed as in case 1."

In addition to obtaining background information on this patent application, VerticalNews editors also obtained the inventors' summary information for this patent application: "Technical Problem

"In order to use 64QAM or MIMO, it is necessary to use the MAC-ehs protocol. Where the MAC-ehs protocol is used, the RLC PDU size may have a fixed length or a variable length, and thus, for an RLC to operate, it is necessary to set the RLC PDU size to have a fixed length or a variable length.

"However, in the NBAP protocol (Node B Application Part, 3GPP TS25.433), which is a current call control protocol, an RNC cannot notify a Node B of whether the RLC PDU size has a fixed length or a variable length. FIG. 2 is a chart illustrating parameters in the NBAP protocol. This chart is one illustrated in 3GPP TS 24.4339.2.1.31IA. Referring to FIG. 2, it can be seen that there is no information element for notifying a setting of whether the RLC PDU size has a fixed length or a variable length, and thus, notification of such setting cannot be provided by the NBAP protocol. Consequently, there is a problem that a discrepancy in the setting states of whether the RLC PDU size has a fixed length or a variable length may occur between an RNC and a Node-B.

"When the MAC-ehs protocol is used, the current NBAP supposes that the HS-DSCH MAC-d PDU Size Format IE has a 'Flexible MAC-d PDU Size'. Consequently, an RNC sets the RLC PDU size to have a fixed length, and a Node-B sets the RLC PDU size to have a variable length, which may result in a discrepancy in the state between the RNC and the Node-B.

"If the RLC PDU size is set to have a variable length, the Node-B may give an instruction to change the RLC PDU size to the RNC in flow control. However, the RNC cannot change the RLC PDU size because the RLC PDU size is set to have a fixed length.

"For example, where the Node-B gives an instruction to provide a size larger than the fixed length set in the RNC, to the RNC, the Node-B should be able to receive a PDU with a size larger than the fixed length. However, where the RLC PDU size is set to have a fixed length in the RNC, the RNC segments the data by the fixed length. In that case, use efficiency of system resources such as a band cannot be sufficiently enhanced.

"Also, for example, if the Node-B gives an instruction to provide a size smaller than the fixed length set in the RNC, to the RNC, the RNC in which the RNC PDU size is set to have the fixed length cannot transmit data to the Node-B or sends data with a size exceeding the limit, to the Node-B. In such case, serious failures occur in the flow control and/or system operation.

"FIG. 3 is a chart illustrating a communication mode example for describing a failure in flow control. FIG. 4 illustrates an example of a sequence resulting in occurrence of a defect in flow control.

"In the FIG. 3 example, the RLC PDU size is 82 bytes, the MAC-ehs protocol is used, and MIMO and 64QAM are used.

"In this case, NBAP Maximum MAC-d PDU Size Extended IE, which designates a maximum value of the MAC-d PDU size, is set to 82 bytes.

"Referring to the FIG. 4 sequence, first, an RNC sets the RLC PDU size to have a fixed length (step 901). When MAC-ehs is used, no logical channel multiplexing is performed in the MAC-d layer, and thus, no MAC-d header is provided. Accordingly, in this example, the MAC-d PDU size is equal to the RLC PDU size (step 902).

"The RNC prepares an NBAP: RL SETUP REQUEST message (step 903) and transmits the message to a Node B (step 904). This NBAP: RL SETUP REQUEST message includes a Maximum MAC-d PDU Size Extended IE set to 82 bytes, which is the maximum value of the MAC-d PDU size.

"By receiving the NBAP: RL SETUP REQUEST message, the Node B recognizes that the maximum value of the MAC-d PDU size is 82 bytes (step 904), and sets the maximum value together with information on 64QAM, MIMO and MAC-ehs (step 905).

"After establishment of HSDPA, flow control is started.

"Here, it is assumed that the Node-B decides to set the MAC-d PDU size to a size smaller than 82 bytes in flow control because of a radio channel congestion (step 908). The Node-B sets the maximum value of the MAC-d PDU size to a new value smaller than 82 bytes (step 909) and sends an HS-DSCH CAPACITY ALLOCATION TYPE 2 control frame including a Maximum MAC-d PDU Size Extended IE in which the value has been set, to the RNC (step 910). This frame is a frame used for the Node-B to notify the RNC of control information on the flow control. Examples of the control information in the flow control include MAC-d/c PDU Length, credits and a transmission interval.

"Since the RLC PDU size is set to a fixed length, the RNC cannot transmit data with a length shorter than the fixed length, resulting in data communication being stopped (step 911).

"An object of the present invention is to provide a technique preventing a discrepancy in a state of setting, between devices, regarding whether the data size in data communication has a fixed length or a variable length in a mobile communication system.

"Solution to Problem

"In order to achieve the above object, a mobile communication system according to an aspect of the present invention includes a control device and a base station device,

"wherein data communication between the control device and the base station device is conducted using a fixed-length data size and a variable-length data size;

"wherein the control device transmits information indicating whether a data size of the data communication has a fixed length or a variable length; and

"wherein the base station device receives the information from the control device.

"A control device according to the present invention includes:

"communication means for communicating with a base station device using a fixed-length data size and a variable-length data size; and

"transmission means for transmitting information indicating whether a data size of the data communication has a fixed length or a variable length to the base station device.

"A base station device according to an aspect of the present invention includes:

"communication means for communicating with a control device, using a fixed-length data size and a variable-length data size; and

"reception means for receiving information indicating whether a data size of the data communication has a fixed length or a variable length from the control device.

"A system control method according to an aspect of the present invention provides a communication control method for a mobile communication system including a control device and a base station device,

"wherein data communication between the control device and the base station device is conducted using a fixed-length data size and a variable-length data size;

"wherein the control device transmits information indicating whether a data size of the data communication has a fixed length or a variable length; and

"wherein the base station device receives the information from the control device.

"A device control method according to an aspect of the present invention includes:

"communicating with a base station device, using a fixed-length data size and a variable-length data size; and

"transmitting information indicating whether a data size of the data communication has a fixed length or a variable length, to the base station device.

BRIEF DESCRIPTION OF DRAWINGS

"FIG. 1 is a chart illustrating examples of parameters set in respective cases of HSDPA.

"FIG. 2 is a chart illustrating parameters in the NBAP protocol.

"FIG. 3 is a chart illustrating a communication mode example for describing a flow control failure.

"FIG. 4 is a diagram illustrating an example of a sequence resulting in the occurrence of a flow control failure.

"FIG. 5 is a block diagram illustrating a configuration of RNC 11 according to a first exemplary embodiment.

"FIG. 6 is a block diagram illustrating a configuration of Node-B 12 according to the first exemplary embodiment.

"FIG. 7 is a block diagram illustrating a configuration of a mobile communication system according to a second exemplary embodiment.

"FIG. 8 is a sequence diagram illustrating an operation of a mobile communication system according to the second exemplary embodiment.

"FIG. 9 is a diagram for describing an overview of an NBAP protocol message.

"FIG. 10 is a diagram illustrating an example of change of 3GPP TS 25.433.

"FIG. 11 is a diagram illustrating an example of an HS-DSCH DATA FRAME TYPE 2 according to a third exemplary embodiment.

"FIG. 12 is a sequence diagram illustrating an operation of a mobile communication system according to the third exemplary embodiment.

"FIG. 13 is a diagram illustrating an example of definition of an HS-DSCH MAC-d PDU Size Format according to a fourth exemplary embodiment."

For more information, see this patent application: UEDA, Yoshio; HAYASHI, Sadafuku. Mobile Communication System, Control Device, Base Station Device, System Control Method and Device Control Method. Filed January 24, 2014 and posted May 29, 2014. Patent URL: http://appft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=%2Fnetahtml%2FPTO%2Fsearch-adv.html&r=3625&p=73&f=G&l=50&d=PG01&S1=20140522.PD.&OS=PD/20140522&RS=PD/20140522

Keywords for this news article include: Nec Corporation.

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