Random access channel (RACH) of the long term evolution (LTE) system is used for initial network access and uplink timing synchronization. Unlike the legacy 4-step RACH procedure, a 2-step RACH procedure has been discussed in 3GPP standardization meetings for 5G. Note that, compared with the 4-step RACH procedure in the LTE, the simplified 2-step RACH procedure reduces signaling overhead and transmission latency.
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However, there is no specification for physical channel design for the 2-step RACH procedure. In detail, resource allocation and numerology/format for data transmission/reception on the RACH is not considered in the LTE specification. Thus, the network cannot extract/decode the data received from the UE in the 2-step RACH procedure.
It is therefore an objective to provide a method of data transmission and reception in a random access procedure in order to solve the abovementioned problems.
The present invention discloses a method of data transmission in a random access procedure for a UE of a wireless communication system including a network. The method comprises obtaining a resource allocated for data transmission and a resource allocated for preamble transmission with these resources allocated in a frequency division multiplexing FDM manner, transmitting a preamble and data in the random access procedure to the network according to the obtained resources, and monitoring a response corresponding to the transmitted preamble and data from the network.
The present invention discloses a method of data transmission in a random access procedure for a user equipment (UE) of a wireless communication system including a network. The method comprises transmitting the preamble and data in the random access procedure to the network according to an association among any combination of preambles, multiple access (MA) resources for data transmission and demodulation reference signals (DMRSs) for uplink channel estimation, and monitoring a response corresponding to the transmitted preamble and data from the network.
The present invention discloses a method of data reception in a random access procedure for a network of a wireless communication system including a UE. The method comprises receiving a preamble and data in the random access procedure on resources allocated in a frequency division multiplexing (FDM) manner, from the UE, and transmitting a response corresponding to the received preamble, to the UE.
The present invention discloses a method of data reception in a random access procedure for a network of a wireless communication system including a UE. The method comprises receiving a preamble and data in the random access procedure, from the UE, performing a channel estimation for demodulation of the received data, decoding the received data according to a channel estimation result and an association among any combination of preambles, multiple access (MA) resources for data transmission, and demodulation reference signals (DMRSs) for uplink channel estimation, and transmitting a response corresponding to the received preamble, to the UE.
The present invention further discloses that the resource allocated for data transmission in a random access procedure is predefined in the UE and/or configured by the network via broadcasted system information and/or UE-specific signaling.
These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings.
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Step 300: Start.
Step 310: Transmit the preamble and data in the random access procedure to the network according to an association among any combination of preambles, multiple access (MA) resources for data transmission and demodulation reference signals (DMRSs) for uplink channel estimation.
Step 320: Monitor a response corresponding to the transmitted preamble and data from the network.
Step 330: End.
According to the process 30, the UE decides the preamble, the DMRS if employed, and MA resource by one of the following methods:
In addition, the UE obtains the following information with broadcast system information and/or UE-specific signaling from the network or with pre-defined configurations in the UE. The information includes available resources (i.e. physical time-frequency resources) allocated for preambles and data, and association among any combination of preambles, MA resources and DMRSs if DMRS is employed.
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Step 400: Start.
Step 410: Receive a preamble and data in the random access procedure, from the UE.
Step 420: Perform a channel estimation for demodulation of the received data.
Step 430: Decode the received data according to a channel estimation result and an association among any combination of preambles, multiple access (MA) resources for data transmission, and demodulation reference signals (DMRSs) for uplink channel estimation.
Step 440: Transmit a response corresponding to the received preamble, to the UE.
Step 450: End.
According to process 40, the network processes (e.g. decoding/demodulating) the data in the random access procedure with the MA resource and the DMRS if DMRS is employed, wherein the DMRS and MA resource are directly or indirectly associated with the received preamble. Thus, the network is able to decode/demodulate the data in the random access procedure without blindly detecting all available MA resources for RACH data multiplexing and all available DMRS for uplink channel estimation, so that detection complexity is reduced.
In an embodiment, an association table is established on both of the UE and the network, wherein the association table includes mapping information among preambles, DMRSs and MA resources. For example, the preamble is mapped to the MA resource, the preamble is mapped to the DMRS, and/or the DMRS is mapped to the MA resource. In such a manner, the UE and the network know which MA resource(s)/DMRS should be used for data transmission and reception when a preamble is selected/detected.
Note that, while preambles can be multiplexed by ZC-like sequences, data transmitted in the random access procedure (hereafter called RACH data) is multiplexed by means of an uplink multiple access (ULMA) scheme. RACH data from different UEs are multiplexed by an uplink multiple access scheme onto same or different time-frequency resources depending on the selected ULMA scheme. An ULMA scheme can be a non-orthogonal multiple access (NOMA) or an orthogonal multiple access (OMA) scheme. By the NOMA scheme, RACH data from different UEs can be multiplexed onto the same time-frequency resource. On the other hand, by the OMA scheme, RACH data from different UEs can be multiplexed onto same or different time-frequency resources depending on which MA resource have been chosen. With abovementioned ULMA scheme, the MA resource of the present invention is comprised of a MA physical resource and a MA signature wherein a MA physical resource is comprised of a physical time-frequency block and a MA signature includes at least one of the following: codeword, sequence, interleaving and/or mapping pattern, spatial-dimension, power-dimension, time-frequency resource, etc. For example, the Group Orthogonal Coded Access (GOCA) is a sequence-based uplink NOMA scheme which multiplexes different UEs in the sequence domain. Its corresponding MA signatures are hence the defined sequences. Another example is the Repetition Division Multiple Access (RDMA) uplink NOMA scheme which applies different cyclic repetition patterns for interleaving. Therefore, MA signatures for RDMA can be defined interleaving and/or mapping patterns. Yet another example is the Orthogonal Multiplexing Access (OMA) scheme. When its MA signature is defined by (smaller) time-frequency resource, it implies data from different users are multiplexed onto different time-frequency resources within the given (larger) MA physical block. In this case, RACH data from different UEs are multiplexed onto different time-frequency resources (within the given MA physical block). On the other hand, when the MA signature is defined in the power-dimension for the OMA scheme, then RACH data from different UEs can be multiplexed on the same time-frequency resource block.
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In an embodiment, the preamble is associated with DMRS. Please refer to
In another embodiments, the DMRS is associated with MA resource. Please refer to
In other embodiments, the preamble is directed associated with DMRSs and indirectly associated with MA resource. Please refer to
Regarding physical time-frequency resource allocation, the network can allocate the physical resource for RACH data transmission with respect to that for RACH preambles in a time division multiplexing (TDM) manner or in a frequency division multiplexing (FDM) manner.
With TDM-type resource allocation, the timing advance (TA) estimated by the preamble in the front can be directly applied to the demodulation of the following data. In
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The abovementioned steps of the processes/operations including suggested steps can be realized by means that could be a hardware, a software, or a firmware known as a combination of a hardware device and computer instructions and data that reside as read-only software on the hardware device or an electronic system. Examples of hardware can include analog, digital and mixed circuits known as microcircuit, microchip, or silicon chip. Examples of the electronic system can include a system on chip (SOC), system in package (SiP), a computer on module (COM) and the communication device 20.
In conclusion, the present invention is addressed at physical channel design for the 2-step RACH procedure, especially to resource allocation (TDM-type/FDM-type resource allocation) for preamble and data transmission in the 2-step RACH procedure. In addition, the present invention provides a mechanism to associate the preamble directly or indirectly with the MA resource and DMRS, so as to decode/demodulate the RACH data in the 2-step RACH procedure. Thus, 2-step RACH procedure with data transmission and reception can be realized in the 5G LTE for reduces signaling overhead and transmission latency.
Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.
This application claims the benefit of U.S. Provisional Application No. 62/416,740, filed on Nov. 3, 2016 and entitled “2-step random access physical channel design”, the contents of which are incorporated herein in their entirety.
Number | Date | Country | |
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62416740 | Nov 2016 | US |