Uplink access method of mobile communication system

0001Description

UPLINK ACCESS METHOD OF MOBILE COMMUNICATION

SYSTEM

0004Disclosure of Invention Technical Solution

0005[1] The present invention relates to uplink access method for transmitting and receiving a point-to-multipoint service (i.e., Multimedia Broadcast Multicast Service (MBMS)) in an E-UMTS (Evolved Universal Mobile Telecommunications System) and, more particularly, a network transmits a response request message with respect to a point- to-multipoint service to a terminal, the terminal transmits a response message using an allocated uplink access preamble included in the response request message, thereby effectively performing a counting procedure with respect to the point-to-multipoint at a minimum overhead.

0006[2] Figure 1 is a network structure of the E-UMTS, a mobile communication system applicable to the related art and the present invention.

0007[3] The E-UMTS system has been evolved from the UMTS system, for which the 3GPP is proceeding with the preparation of the basic specifications applicable thereto. The E- UMTS system may be referred to as an LTE (Long Term Evolution) system.

0008[4] With reference to HG. 1 , the E-UMTS network includes an E-UTRAN and an EPC

0009(Evolved Packet Core). An interface between the E-UTRAN and the EPC can be used. An Sl interface can be used between the eNodeBs and the EPC. The eNodeBs are connected with each other through an X2 interface, and the X2 interface may be present between adjacent eNodeBs in a meshed network structure.

0010[5] Figure 2 and 3 illustrates a structure of the radio access interface protocol for the E-

0011UMTS.

0012[6] The radio access interface protocol has horizontal layers including a physical layer, a data link layer and a network layer, and has vertical planes including a user plane for transmitting data information and a control plane for transmitting control signals.

0013[7] The protocol layers can be divided into a first layer (Ll), a second layer (L2) and a third layer (L3) based upon the three lower layers of an open system interconnection (OSI) standard model that is well-known in the art of communication systems.

0014[8] The physical layer, the first layer, provides an information transmission service to an upper layer by using a physical channel. The physical layer is connected with a medium access control (MAC) layer located at a higher level through a transport channel, and data between the MAC layer and the physical layer is transferred via the transport channel. Between different physical layers, namely, between physical layers of a transmission side and a reception side, data is transferred via the physical channel.

0015[9] The MAC layer of the second layer provides a service to a radio link control (RLC) layer, an upper layer, via a logical channel. The RLC layer of the second layer supports a reliable data transmission. The function of the RLC layer can be implemented as a function block within the MAC layer, and in this case, the RLC layer may not be present. A PDCP layer of the second layer performs a header compression function for reducing unnecessary control information so that data transmitted by using IP packets such as IPv4 or IPv6 can be effectively transmitted via a radio interface with a relatively small bandwidth.

0016[10] A radio resource control (RRC) layer located at the lowest portion of the third layer

0017(L3) is only defined in the control plane and controls logical channels, transport channels and the physical channels in relation to the configuration, reconfiguration, and release of the radio bearers (RBs). Here, the RB signifies a service provided by the second layer (L2) for data transmission between the terminal and the E-UTRAN. A Non- Access Stratum (NAS) layer located on the most upper portion of the RRC layer performs functions such as a SAE (System Architecture Evolution) bearer management, an authentication, an idle mode mobility handling, a paging origination in LTE-IDLE, or a security control for the signalling between aGW and UE, etc.

0018[11] Downlink transport channels for transmitting data from the network to the terminal, include a broadcast channel (BCH) for transmitting system information and a downlink shared channel (SCH) for transmitting the user traffic or the control message. Downlink multicast, traffic of a broadcast service or a control message can be transmitted through the downlink SCH or through a separate downlink multicast channel (MCH).

0019[12] Uplink transport channels for transmitting data from the terminal to the network include a random access channel (RACH) for transmitting an initial control message and an uplink SCH for transmitting the user traffic and the control message.

0020[13] Logical channels located above the transport channels and mapped to the transport channels, include a broadcast control channel (BCCH), a paging control channel (PCCH), a common control channel (CCCH), a multicast control channel and a multicast traffic channel (MTCH).

0021[14] Figure 4 shows an exemplary structure of the physical channel. The physical channel transfers signalling and data between the UE Layer 1 (Ll) and the eNB Layer 1 (Ll). As shown in Figure 4, the physical channel transfers the signalling and the data, which consists of a plurality of sub-carriers in frequency and a plurality of symbols in time (i.e., 6 or 7 symbols constitute one sub-frame which is 0.5 ms in length). One sub- frame consists of a plurality of resource blocks and one resource block comprises a plurality of symbols and a plurality of sub-carriers. One sub-frame is 0.5ms and TTI (Transmission Time Interval) which is a unit time for data transmission is lms corresponded to two sub-frames. The particular symbol(s) of the sub-frame (e.g. the first symbol of the sub-frame) can be used for the L1/L2 control channel. The L1/L2 control channel carries L1/L2 control information (signalling).

0022[15] Usually, a network can perform a MBMS counting procedure if the network needs to know there is any existed terminal that receives a particular MBMS service in a particular cell or needs to count a number of terminals. Here, the MBMS counting procedure is referred that the processing steps of transmitting an access information message via a MCCH (Multicast Control Channel) by the network and transmitting a RRC connection setup message or a cell update message in response to the access information message by the terminal.

0023[16] In the related art, a RRC connection request message or a cell update message is transmitted via a RACH (Random Access Channel) channel. The RACH channel can be divided into a RACH preamble part and a RACH message part. When the terminal transmits the response message in response to the access information message, the RACH preamble is transmitted first, then the RRC connection message or the cell update message is transmitted through the RACH message to the network.

0024[17] Thus, in the related art, the RACH preamble has to be transmitted before a transmission of the uplink RACH message. This causes a time delay and/or a great amount of overhead to perform the counting procedure [i.e., MBMS counting procedure].

0025[18] The present invention has been developed in order to solve the above described problems of the related art. As a result, the present invention may provide a method for transmitting and receiving a point-to-multipoint (i.e., MBMS service) to reduce a time for performing a counting procedure and to minimize an uplink overhead.

0026[19] To implement at least the above feature in whole or in parts, the present invention may provide a method of receiving a response request with respect to a particular service from a network; transmitting a response message to the network using an allocated uplink access preamble included in the received response request;

0027[20] The present invention may also provide a method of transmitting a response request with respect to a particular service, wherein the response request includes uplink transmission information related to a preamble that will be used by a terminal for transmitting a response that responds to the response request, wherein the uplink transmission information includes a service dedicated signature; and receiving the response from the terminal that uses the uplink transmission information for a transmission of the response.

0028[21] The present invention may also provide a mobile terminal for uplink access for a wireless communications system, the mobile terminal comprising: a transceiver adapted to transmit or receive a service data; a memory adapted to store the service data transmitted or received via the transceiver or from an external source; and a processor cooperating with the transceiver and the memory and adapted to perform the steps of, receiving a response request with respect to a service, wherein the response request includes uplink transmission information related to a preamble that will be used for transmitting a response that responds to the response request, wherein the uplink transmission information includes a service dedicated signature; and transmitting the response using the uplink transmission information.

0029[22] Additional features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.

0030[23] Figure 1 shows an exemplary network structure of the E-UMTS.

0031[24] Figure 2 shows an exemplary structure of the control plane of the radio access interface protocol for the E-UMTS.

0032[25] Figure 3 shows an exemplary structure of the user plane of the radio access interface protocol for the E-UMTS.

0033[26] Figure 4 shows an exemplary structure of the physical channel.

0034[27] Figure 5 shows an exemplary diagram illustrating an uplink access method for a point-to-multipoint service in accordance with the present invention.

0035[28] Figure 6 shows an exemplary diagram illustrating a transmission of an uplink access preamble between a terminal and a network when an access information message includes a Counting on in accordance with the present invention.

0036[29] Figure 7 shows an exemplary diagram illustrating a transmission of an uplink access preamble between a terminal and a network when an access information message includes a Counting off in accordance with the present invention.

0037[30] One aspect of the present invention is the recognition by the present inventors regarding the problems and drawbacks of the related art described above and explained in more detail hereafter. Based upon such recognition, the features of the present invention have been developed.

0038[31] Although the present invention is shown to be implemented in a mobile communication system, such as a UMTS and E-UMTS developed under 3GPP specifications, the present invention can also be applied to other communication systems operating in conformity with different standards and specifications.

0039[32] Thus, in order to reduce the delays occurring during the counting procedure and to reduce uplink overhead according to the present invention, the mobile terminal receives a response request message with respect to a particular service from the wireless network, then transmits a response message through an uplink access preamble with respect to the particular service that was set in the response request message, and receives a response message with respect to the uplink access preamble from the wireless network.

0040[33] The response request message may include information related to the uplink access preamble. The information related to the uplink access preamble may include a signature used by the uplink access preamble.

0041[34] The mobile terminal transmits the signature via the uplink access preamble.

0042[35] If a positive (affirmative) response with respect to the uplink access preamble is received, the mobile terminal may suspend (or interrupt) the transmission of the uplink access preamble. If a negative response with respect to the uplink access preamble is received, the mobile terminal may continue to transmit the uplink access preamble.

0043[36] According to the present invention, the wireless network may perform the counting procedure for the particular MBMS service. Figure 5 shows an exemplary diagram illustrating an uplink access method for a point-to-multipoint service in accordance with the present invention.

0044[37] In order to begin the counting procedure with respect to a particular service, the wireless network transmits an access information message via a MCCH channel. (SlO) The access information message may be transmitted periodically according to the period set by the wireless network. The access information message may include a service identifier with respect to that service or a service identifier with respect to a session of that service, and may include "Counting On" or "Counting Off, etc. to thus indicate (or instruct) whether the counting procedure with respect to that service should proceed or not or to indicate (or instruct) whether an uplink response is needed or not.

0045[38] Also, the access information message may include uplink transmission information for the uplink access preamble used when transmitting an uplink response with respect to the access information. The uplink transmission information may include a time frame(s) in which the preamble is transmitted, one or more frequencies, code(s), signature(s), and the like. Here, the signature refers to a service-dedicated signature that corresponds to the service. When the service-dedicated signature corresponding to the particular service is allocated, the wireless network may designate (or specify) the time period for when the signature is used or the point in time when the signature use is terminated (i.e., usage termination time), and the information related to such time period or usage termination time may be included in the uplink transmission information together with the signature.

0046[39] The mobile terminal that wishes to receive the particular service receives the access information message via the MCCH channel, and may check the access information message. (SIl) If the access information corresponds to the particular service (namely, if the service identifier with respect to the particular service or the session identifier with respect to a session of the particular service is included in the access information), and also, if the access information indicates (or instructs) the progress (or proceeding) of the counting procedure or if uplink response is requested (i.e., of "Counting On"), the mobile terminal responds to the access information by using the uplink transmission information included in the access information. Here, the mobile terminal responds by using an uplink access preamble. (S 12) The preamble used by the mobile terminal transmits the signature or code included in the uplink transmission information, and transmission on the uplink is performed upon being adapted to the time frame and frequency included in the uplink transmission information. Specifically, those mobile terminals wishing to receive the particular service transmit the uplink access preamble, by using the service-dedicated signature corresponding to the particular service, during the time period or until the usage termination time

0047[40] The wireless network attempts reception of the uplink access preamble according to the uplink transmission information. The uplink access preamble includes the service- dedicated signature. Accordingly, the wireless network may simultaneously receive the same service-dedicated signature from a plurality of mobile terminals via the same sub-carrier. Because multiple mobile terminals transmit with the same signature, the wireless network cannot distinguish each of the mobile terminals, and if multiple mobile terminals transmitted the same service-dedicated signature, a single uplink access preamble that transmits the same service-dedicated signature is received. Here, as the number of mobile terminals that transmit the same preamble increases, the probability for the wireless network of receiving a preamble having even greater energy is increased. Upon receiving the uplink access preamble, the wireless network may measure the reception energy or power of the preamble, and such measured energy or power may be used to determine the existence of any mobile terminals wishing to receive the service in the current cell and to determine the approximate total number of mobile terminals. (S 13) For example, a threshold value for the energy or power may be set, and if the reception energy or power of the service-dedicated signature(s) received during a certain period of time is found to exceed a particular threshold value, it would be determined that one or more mobile terminals wishing to receive the particular service exists in the current cell, and otherwise, it can be determined that there are no mobile terminals wishing to receive the particular service within the current cell.

0048[41] When the wireless network receives the uplink access preamble, a response may be performed in two ways. The first method is to respond via an access information message. (S 14) As the access information message is transmitted periodically, a single access information message may simultaneously provide responses with respect to preambles transmitted for the particular service during a previous access period. The second method is to respond via an uplink access response message. (S 14) In this case, the uplink access response message is transmitted on the downlink during a particular time period after receiving the preamble, and includes a service identifier or session identifier of the particular service and a service-dedicated signature, a positive response or negative response information. In response to the uplink access preamble, the wireless network may transmit an access information message or an uplink access response message, or an access information message and an uplink access response message may be transmitted together.

0049[42] The wireless network may transmit the uplink access response message via a downlink SCH channel. In this case, a L1/L2 control channel (PDCCH) for the downlink SCH channel may inform whether the uplink access response message is transmitted or not, and the L1/L2 control channel also inform a radio resource that used for transmitting the uplink access response message. Here, in order to inform whether the uplink access response message is transmitted or not, the L1/L2 control channel may transmit a service identity/session identity of the service, a MBMS RNTI (Radio Network Temporary Identity) that corresponds with the service identity, a RA- RNTI (Random Access RNTI) that corresponds with the uplink access preamble, or a RA-RNTI that used for all MBMS in a corresponding cell.

0050[43] The terminal may receive the L1/L2 control channel, and the terminal may receive the uplink access response message via the downlink SCH channel when the L1/L2 control channel includes the identity described above. When the terminal fails to receive the uplink access response message that responds to a previously transmitted uplink access preamble, the terminal may retransmit the uplink access preamble after certain time period. (S 15) To do this, the terminal may re-obtain uplink transmission information by receiving the access information again. Thereafter, the terminal may retransmit the uplink preamble using the re-obtained uplink transmission information. Or, the terminal may retransmit the uplink access preamble according to an access information message by receiving transmitted access information in next access period after transmitting the uplink access preamble in current access period.

0051[44] To be more specific, the terminal may receive a transmitted access information message in next (coming) access period, in case of an uplink access preamble is transmitted, an uplink access response message with respect to a transmitted uplink access preamble is not received, or an uplink access response message with respect to a transmitted uplink access preamble is received but it contains a negative response. Here, the uplink access preamble may be retransmitted (S 15) when the access information indicates to perform a counting procedure or to request an uplink response [i.e., access information indicates "Counting on"] (S 14). The uplink access preamble may not be retransmitted when the access information indicates to stop performing of the counting procedure or not to request an uplink response [i.e., access information indicates "Counting off] (S17).

0052[45] The terminal may terminate a retransmission of an uplink access preamble, in case of the terminal receives a response message after transmitting an uplink access preamble but it contains a negative response, or such negative response indicates to stop a transmission of the uplink access preamble. If the negative response of the uplink access response message includes uplink access delay time information, the terminal may retransmit the uplink access preamble only after such delay time. In this case, the terminal may retransmit [i.e., "Counting on"] or may terminate to retransmit [i.e., "Counting off] the uplink access preamble according to an access information message which is a transmitting access information message after the delay time.

0053[46] If terminal receives an access information message and the received access information message indicates a "Counting off with having a delay time, the terminal may retransmit the uplink access preamble after such delay time. Namely, the terminal may receive a transmitting access information message after the delay time, then may retransmit the uplink access preamble based on the access information that indicates a "Counting on", or may terminate to retransmit the uplink access preamble based on the access information that indicates a "Counting off."

0054[47] When the terminal retransmits the uplink access preamble, within a duration time or before a usage termination time, the terminal may retransmit the uplink access preamble using a previously used service dedicated signature. If recently received access information message transmits a new service dedicated signature, the terminal may retransmit the uplink access preamble using the new service dedicated signature instead of using the previously used service dedicated signature. Also, if the terminal tries to retransmit the uplink access preamble beyond the duration of time or after the usage termination time, the terminal may need to receive information related to a new service dedicated signature again by receiving access information one more time. As such, in this case, the terminal may have to retransmit the uplink access preamble with using the new service dedicated signature only.

0055[48] The terminal may transmit an uplink access preamble by selecting random signature when a previously service dedicated signature is no longer to be used (i.e., when the terminal retransmit an uplink access preamble beyond the duration of time or after the usage termination time and the terminal can not receive an access information) Here, when the terminal receives a response in response to the uplink access preamble, the terminal may transmit a service identity (for a service that the terminal wishes to receive), a session identity, or the like parameters via an uplink SCH channel to a wireless network.

0056[49] The wireless network may try to receive an uplink access preamble based on uplink transmission information, may perform counting procedure for a number of the uplink access preamble. (S 16) When the wireless network receives enough numbers of the uplink access preamble, the wireless network may broadcast to terminate the counting procedure through access information message. Also, the wireless network may broadcast to request a termination of a transmission of the uplink access preamble. (S17)

0057[50] Namely, as illustrated in Figure 7, the wireless network may indicate "Counting off via an access information message to the terminal that wishes to receive a particular service or already received the particular service. When the wireless network does not receive enough number of the uplink access preamble, the wireless network may broadcast to continue to perform the counting procedure and to request the transmission of the uplink access preamble. As such, as illustrated in Figure 6, the wireless network may indicate "Counting on" via the access information message to the terminal that wishes to receive a particular service or already received the particular service.

0058[51] The present invention may provide a method of uplink access for a wireless communications system, the method comprising: receiving a response request with respect to a service, wherein the response request includes uplink transmission information related to a preamble that will be used for transmitting a response that responds to the response request, wherein the uplink transmission information includes a service dedicated signature; and transmitting the response using the uplink transmission information, wherein the response request is an access information message, the response request is received through a MCCH (Multicast Control Channel), the response request is used for counting a number of terminals that subscribed to the service, the service is related to at least one of a point to multipoint service, a multicast service, a broadcast service, and a multimedia service, the response request includes at least one of a service identity, a session identity, a Counting on, or a Counting off, the uplink transmission information includes at least one of a time frame for a transmission of the preamble, a frequency of the preamble, a preamble code, or a signature of the preamble, the response includes a service identity or a session identity, the response is transmitted to a network only if the response request includes the Counting on, a transmission of preamble is stopped if a positive response with respect to a previously transmitted preamble is received from a network, and the transmission of the preamble continues if a negative response with respect to previously transmitted preamble is received from the network, receiving a response message in response to the transmitted response, the response message is either an access information message or an uplink access response message received on a downlink SCH, retransmitting the response if the response message is not received within a certain time frame, a duration time or a termination time for using the service dedicated signature is set by a network, information related to the duration time or the termination time for using the service dedicated signature is included in the uplink transmission information, the service dedicated signature is retransmitted by the network when previously received service dedicate signature was not used in the duration time or before the termination time, a MBMS Radio Network Temporary Identity (RNTI) that corresponds to a service identity is received through a PDCCH (Physical Dedicated Control Channel).

0059[52] The present invention may also provide a method of uplink access in a wireless communications system, the method comprising: transmitting a response request with respect to a service, wherein the response request includes uplink transmission information related to a preamble that will be used by a terminal for transmitting a response that responds to the response request, wherein the uplink transmission information includes a service dedicated signature; and receiving the response from the terminal that uses the uplink transmission information for a transmission of the response, the response request is an access information message, the response request is used for counting a number of terminals that subscribed to the service and the response request is transmitted through a MCCH (Multicast Control Channel), the service is related to at least one of a point to multipoint service, a multicast service, a broadcast service, and a multimedia service, the response request includes at least one of a service identity, a session identity, a Counting on, or a Counting off, the uplink transmission information includes at least one of a time frame for a transmission of the preamble, a frequency of the preamble, a preamble code, or a signature of the preamble, the response includes a service identity or a session identity, transmitting a response message in response to the received response, the response message is either an access information message or an uplink access response message received on a downlink SCH, setting a duration time or a termination time for using the service dedicated signature, information related to the duration time or the termination time for using the service dedicated signature is included in the uplink transmission information, retransmitting the service dedicated signature when previously transmitted service dedicate signature was not used by the terminal in the duration time or before the termination time, a MBMS Radio Network Temporary Identity (RNTI) that corresponds to a service identity is transmitted to the terminal through a PDCCH (Physical Dedicated Control Channel).

0060[53] Although the present invention is described in the context of mobile communications, the present invention may also be used in any wireless communication systems using mobile devices, such as PDAs and laptop computers equipped with wireless communication capabilities (i.e. interface). Moreover, the use of certain terms to describe the present invention is not intended to limit the scope of the present invention to a certain type of wireless communication system. The present invention is also applicable to other wireless communication systems using different air interfaces and/or physical layers, for example, TDMA, CDMA, FDMA, WCDMA, OFDM, EV- DO, Wi-Max, Wi-Bro, etc.

0061[54] The exemplary embodiments may be implemented as a method, apparatus or article of manufacture using standard programming and/or engineering techniques to produce software, firmware, hardware, or any combination thereof. The term "article of manufacture" as used herein refers to code or logic implemented in hardware logic (e.g., an integrated circuit chip, Field Programmable Gate Array (FPGA), Application Specific Integrated Circuit (ASIC), etc.) or a computer readable medium (e.g., magnetic storage medium (e.g., hard disk drives, floppy disks, tape, etc.), optical storage (CD-ROMs, optical disks, etc.), volatile and non- volatile memory devices (e.g., EEPROMs, ROMs, PROMs, RAMs, DRAMs, SRAMs, firmware, programmable logic, etc.).

0062[55] Code in the computer readable medium may be accessed and executed by a processor. The code in which exemplary embodiments are implemented may further be accessible through a transmission media or from a file server over a network. In such cases, the article of manufacture in which the code is implemented may comprise a transmission media, such as a network transmission line, wireless transmission media, signals propagating through space, radio waves, infrared signals, etc. Of course, those skilled in the art will recognize that many modifications may be made to this configuration without departing from the scope of the present invention, and that the article of manufacture may comprise any information bearing medium known in the art.

0063[56] Any reference in this specification to "one embodiment," "an embodiment,"

0064"example embodiment," etc., means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. The appearances of such phrases in various places in the specification are not necessarily all referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with any embodiment, it is submitted that it is within the purview of one skilled in the art to effect such feature, structure, or characteristic in connection with other ones of the embodiments.

0065[57] Although embodiments have been described with reference to a number of illustrative embodiments thereof, it should be understood that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the spirit and scope of the principles of this disclosure. More particularly, various variations and modifications are possible in the component parts and/or arrangements of the subject combination arrangement within the scope of the disclosure, the drawings and the appended claims. In addition to variations and modifications in the component parts and/or arrangements, alternative uses will also be apparent to those skilled in the art.

0066[58] As the present invention may be embodied in several forms without departing from the spirit or essential characteristics thereof, it should also be understood that the above-described embodiments are not limited by any of the details of the foregoing description, unless otherwise specified, but rather should be construed broadly within its spirit and scope as defined in the appended claims, and therefore all changes and modifications that fall within the metes and bounds of the claims, or equivalents of such metes and bounds are therefore intended to be embraced by the appended claims.