Method and apparatus for accessing a random access channel by selectively using dedicated or contention-based preambles during handover

Method and device for selective use of dedicated or competition-based pre-sequence storage codes to obtain random access channels by borrowing oil during handover

This application is related to wireless communication.

In the 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) wireless communication system, when the wireless transmit/ receive unit (WTRU) performs handover to the target cell, the WTRU uses a dedicated preamble code to access the network road. The preamble code is a signal sent from the WTRU to the evolved node-B (eNB) to detect timing misalignment in the uplink (UL) during the handover procedure. Therefore, the target cell needs to reserve a dedicated preamble code for the WTRU. However, when a large number of WTRUs switch to the same target cell in a short amount of time, the non-contention-based random access channel (RACH) used by the eNB to provide configuration information of the dedicated preamble will become excessive. load. Due to the RACH overload, a more effective mechanism is needed to use the dedicated pre-sequence code during the handover.

Here is disclosed a method and device that allows efficient use of dedicated preamble memory codes to access RACH in Evolved Universal Terrestrial Radio Access (E-UTRA) during handover. The WTRU may use a dedicated pre-sequence code stored in a reserved (or pre-configured) frame instead of in each frame. Or, when the dedicated preamble code is not reserved, or the RACH access attempt using the dedicated preamble code is unsuccessful, the WTRU may use the contention-based preamble code in other random access opportunities.

The term "wireless transmit/receive unit (WTRU)" referred to below includes but is not limited to user equipment (UE), mobile station, fixed or mobile subscriber unit, pager, cellular phone, personal digital assistant (PDA), computer or Any other type of user equipment that can operate in a wireless environment. The term "base station" referred to below includes but is not limited to evolved node-B (eNB), site controller, access point (AP), or any other type of interface connection device that can operate in a wireless environment.

Disclosed herein is a method and device that allow the effective use of dedicated preamble codes for the WTRU to perform handover in E-UTRA. The WTRU may use reserved (or pre-configured) frames instead of dedicated preamble codes in each frame. Or, when the dedicated preamble is not reserved, the WTRU can use the contention-based preamble in other random access occasions.

The eNB will reserve a dedicated preamble code in N of every M random access occasions, instead of reserving the dedicated preamble code of the WTRU used for handover in each random access occasion (for example, every 10ms), where The parameter M is defined as the period of reserved dedicated pre-sequence code storage. The random access timing is the period when the RACH can be accessed. In this case, the preferable value of N is 1.

As shown in Figure 1, this value causes the eNB to interleave some WTRUs that share a dedicated preamble memory code in the time domain. WTRU 1 uses the dedicated preamble memory code only in the first random access occasion of every four random access occasions. WTRU 2 uses the dedicated preamble memory code only in the second random access occasion of every four random access occasions. WTRU 3 uses the dedicated preamble memory code only in the third random access occasion of every eight random access occasions. Therefore, the dedicated preamble memory code is effectively shared by 3 WTRUs in the time domain.

The network will monitor and determine the values of the parameters N and M based on the load on the non-contention RACH. Although different values of M can be configured, the larger period must be an integer multiple of the smaller preamble code period. In this way, WTRUs with different dedicated preamble configurations can share the same preamble without conflict in the time domain. A set of preferred examples of different reserved dedicated preamble memory cycles are M=1, 2, 4, and 8.

Figure 2 shows a wireless communication system 200, which includes a WTRU 205 and an eNB 210. The eNB 210 reserves a dedicated preamble memory code for the WTRU in N of the M random access occasions, and the duration reaches the maximum allowable handover interruption time. When a handover decision is made, through a handover command or through a specific medium access control (MAC) protocol data unit (PDU), the eNB 210 may transmit the reserved dedicated preamble configuration information 215 to the WTRU 205. The WTRU 205 includes a transmitter 225, a receiver 230 that receives the preamble from the WTRU 205, a processor 235, and a maximum handover interrupt timer 240. The eNB 110 includes a transmitter 245 configured to transmit reserved dedicated preamble configuration information 215, a receiver 250 that receives the preamble from the WTRU 205, and a processor 255. The processor 255 includes a preamble resource manager 260 for allocating preamble codes to the WTRU 205.

The WTRU 205 transmits a dedicated or contention-based preamble 220 to the eNB 210 so that the WTRU 205 can access the RACH to complete the handover procedure. If the RACH access attempt performed by the WTRU 205 fails when the dedicated preamble code is used, the WTRU 205 will use the contention-based preamble code in subsequent random access opportunities until the WTRU 205 RACH access attempt Success, or until a random access opportunity occurs where there is a reserved dedicated preamble code.

Still referring to Figure 2, the WTRU 200 is configured to access the RACH during the handover. The processor 235 is configured to initiate the handover and start the maximum handover interrupt timer 240. The transmitter is configured to transmit the dedicated preamble to try to access the RACH under the condition that the dedicated preamble is reserved in the current random access opportunity and the maximum handover interrupt timer has not expired; and is configured It is used to transmit the contention-based preamble to try to access the RACH under the condition that the dedicated preamble is not reserved in the current random access opportunity.

The transmitter 225 in the WTRU 200 is further configured to transmit a contention-based preamble to try to access the RACH when the maximum handover interrupt timer has expired. The transmitter 225 is further configured to transmit the contention-based preamble memory code in the subsequent random access opportunity under the condition that the failure to access the RACH has failed, until a successful RACH access attempt occurs, or until a successful RACH access attempt occurs. Where there is a reserved dedicated pre-sequence memory code random access timing occurs.

Under the condition that the dedicated pre-stored code is reserved in the current random access opportunity and the maximum handover interrupt timer has not expired, a non-contention-based procedure is used. Under the condition that the dedicated pre-stored code is not reserved in the current random access opportunity and the maximum handover interrupt timer has expired, a contention-based random access procedure is used.

Fig. 3 is a flowchart of a procedure 300 for using reserved dedicated preamble or contention-based random access preamble during the handover. Referring to Figures 2 and 3, the processor 235 in the WTRU 205 initiates handover to the target cell and starts the maximum handover interrupt timer 240 in the WTRU 205 (305). When a random access opportunity occurs (310), the processor 235 makes a determination as to whether the maximum handover interrupt timer 240 has expired (315). If the maximum switching interrupt timer 240 has not expired before the random access opportunity occurs, the processor 235 determines whether there is a reserved dedicated preamble in the current random access opportunity (step 320).

If there is a reserved dedicated preamble code in the current random access opportunity, the WTRU uses the dedicated preamble code in random access, and uses a non-contention random access procedure between the WTRU 205 and the eNB 210 to A RACH access attempt is made (step 325). The non-contention-based random access procedure is a two-step random access procedure, which does not include the transmission of RACH message 3 in the uplink and contention resolution in the downlink (and contention resolution). Random access program comparison).

If the reserved dedicated preamble code does not exist in the current random access opportunity, the WTRU uses the contention-based preamble code in random access, and uses the contention-based code between the WTRU 205 and the eNB 210 Random access procedure for RACH access attempt (step 330). The contention-based random access procedure is a four-step random access procedure, which includes the transmission of the RACH message 3 in the uplink and contention resolution in the downlink. The contention-based preamble code can be randomly selected from a group of contention-based preamble code.

In step 335, a determination is made whether the RACH access attempt was successful. If the WTRUs RACH access attempt fails when the WTRU uses the reserved dedicated preamble, then the WTRU will use the contention-based preamble in subsequent random access opportunities until the WTRUs RACH access attempt Success, or until there is a reserved dedicated preamble random access opportunity occurs.

Since the possibility of successful RACH access is high when a dedicated preamble code is used, the method of attempting RACH access attempts by alternating non-contention and contention-based RACH access attempts is effective for preamble code resources.

Example

1. A method for a wireless transmit/receive unit (WTRU) to access a random access channel (RACH) during a handover, the method comprising: the WTRU initiates a handover procedure; and starts a maximum handover interrupt timer in the WTRU; And under the condition that the dedicated preamble code is reserved in the current random access opportunity and the maximum handover interrupt timer has not expired, the WTRU transmits the dedicated preamble code to try to access the RACH.

2. A method for a wireless transmit/receive unit (WTRU) to access a random access channel (RACH) during a handover, the method comprising: the WTRU initiates a handover procedure; and starts a maximum handover interrupt timer in the WTRU; And under the condition that the dedicated preamble code is not reserved in the current random access opportunity, the WTRU transmits the contention-based preamble code to try to access the RACH.

3. The method according to any one of embodiments 1 and 2, further comprising: determining that the maximum handover interrupt timer has expired; and the WTRU transmits a contention-based preamble to try to access RACH.

4. The method according to any one of the embodiments 1-3, the method further includes: failing to access the RACH; and the WTRU transmits the contention-based preamble in the subsequent random access opportunity, Until a successful RACH access attempt occurs, or until a random access opportunity in which there is a reserved dedicated preamble memory code occurs.

5. The method as described in any one of embodiments 1-4, wherein the dedicated preamble code is reserved in the current random access opportunity and the maximum handover interrupt timer has not expired Use non-contention based procedures.

6. The method as described in any one of the embodiments 1-4, wherein the dedicated pre-sequence stored code is not reserved in the current random access timing and the maximum handover interrupt timer has expired. Competition-based random access procedures.

7. A wireless transmit/receive unit (WTRU) configured to access a random access channel (RACH) during handover, the WTRU comprising: a maximum handover interrupt timer; a processor configured to initiate handover and Start the maximum handover interrupt timer; and the transmitter is configured to transmit the dedicated pre-dedicated pre-existing code under the condition that the dedicated preamble store code is reserved in the current random access opportunity and the maximum handover interrupt timer has not expired Store the code in order to try to access the RACH.

8. A wireless transmit/receive unit (WTRU) configured to access a random access channel (RACH) during handover, the WTRU comprising: a maximum handover interrupt timer; a processor configured to initiate handover and Start the maximum switching interrupt timer; and the transmitter is configured to transmit a contention-based preamble to try to access under the condition that the dedicated preamble is not reserved in the current random access opportunity The RACH.

9. The WTRU as in any one of embodiments 7 and 8, wherein the transmitter is configured to transmit a contention-based preamble to the condition that the maximum handover interrupt timer has expired Attempt to access the RACH.

10. The WTRU as in any one of embodiments 7-9, wherein the transmitter is configured to transmit contention-based data in subsequent random access occasions under the condition that failure to access the RACH has failed Until a successful RACH random access attempt occurs, or until there is a reserved dedicated pre-sequence memory code in the random access opportunity occurs.

11. The WTRU as in any one of embodiments 7-10, wherein the dedicated preamble code is reserved in the current random access opportunity and the maximum handover interrupt timer has not expired , Use a non-contention-based program.

12. The WTRU as in any one of embodiments 7-10, wherein the dedicated preamble code is not reserved in the current random access opportunity and the maximum handover interrupt timer has expired , Using a competition-based random access program.

Although the features and elements of the present invention are described above in specific combinations, each feature or element can be used alone without other features and elements, or in combination with or without other features and elements of the present invention. Used in various situations. The method or flowchart provided by the present invention can be implemented in a computer program, software, or firmware executed by a general-purpose computer or processor, where the computer program, software, or firmware is included in a computer-readable storage medium in a tangible manner , Examples of computer-readable storage media include read-only memory (ROM), random access memory (RAM), temporary memory, cache memory, semiconductor memory device, internal hard disk, and removable disk. Such as magnetic media, magneto-optical media, and optical media such as CD-ROM discs and digital versatile discs (DVD).

For example, suitable processors include: general-purpose processors, special-purpose processors, traditional processors, digital signal processors (DSP), multiple microprocessors, one or more microprocessors associated with the DSP core, Controller, microcontroller, dedicated integrated circuit (ASIC), field programmable gate array (FPGA) circuit, any other integrated circuit (IC) and/or state machine.

The software-related processor can be used to implement a radio frequency transceiver for use in a wireless transmit and receive unit (WTRU), user equipment (UE), terminal, base station, radio network controller (RNC), or any kind of host computer use. WTRU can be used in combination with modules implemented in hardware and/or software, such as cameras, camera modules, video phones, speaker phones, vibration devices, speakers, microphones, TV transceivers, hands-free headsets, keyboards, Bluetooth<img file="TW201014376A_D0001.tif" />Module, frequency modulation (FM) radio unit, liquid crystal display (LCD) display unit, organic light-emitting diode (OLED) display unit, digital music player, media player, video game console module, Internet browser and / Or any kind of wireless local area network (WLAN) or wireless ultra-wideband (UWB) module.

<p>200. . . Wireless communication system</p><p>205. . . Wireless Transmit/Receive Unit (WTRU)</p><p>210. . . Evolved Node-B (eNB)</p><p>215. . . Configuration information of reserved special pre-sequence code</p><p>220. . . Pre-stored code</p><p>225, 245. . . launcher</p><p>230, 250. . . receiver</p><p>235, 255. . . processor</p><p>240. . . Maximum switching interrupt timer</p><p>260. . . Pre-sequence code storage resource management unit</p>

The present invention can be understood in more detail from the following descriptions, which are given by way of examples and can be understood in conjunction with the accompanying drawings, in which:

Figure 1 shows an example of multiple WTRUs sharing a dedicated preamble during different reserved dedicated preamble cycles;

Figure 2 is a block diagram of a wireless communication system including WTRU and eNB; and

Figure 3 is a flowchart of the procedure for using dedicated or competition-based pre-stored codes during the handover using the system of Figure 2.