CN110945953B

CN110945953B - System and method for advancing random access preamble transmission

Info

Publication number: CN110945953B
Application number: CN201780093428.7A
Authority: CN
Inventors: 张峻峰; 郝鹏
Original assignee: ZTE Corp
Current assignee: ZTE Corp
Priority date: 2017-07-27
Filing date: 2017-07-27
Publication date: 2021-06-08
Anticipated expiration: 2037-07-27
Also published as: WO2019019101A1; CN110945953A

Abstract

A system and method for random access preamble transmission is disclosed. In one embodiment, a method performed by a first communication node comprises: identifying a Random Access Channel (RACH) preamble set, the preamble set comprising: at least one RACH preamble comprising at least one symbol, each symbol having a predetermined length; and a RACH preamble Cyclic Prefix (CP) for each RACH preamble, each RACH preamble CP having a length equal to a combined length of a plurality of first cyclic prefixes, each first cyclic prefix being associated with a respective first symbol; and transmitting a set of RACH preambles having a time advance offset length between the shortest first cyclic prefix length and a combined length of the plurality of first cyclic prefixes.

Description

System and method for advancing random access preamble transmission

Technical Field

The present disclosure relates generally to wireless communications, and more particularly, to systems and methods for random access.

Background

A fifth generation new wireless communication system (e.g., 5G NR) may be implemented in higher and wider frequency bands (e.g., above 3 GHz) in order to achieve higher data rates than the previous generation communication systems. However, high frequency communications may be characterized by more significant channel and penetration losses during transmission of electromagnetic waves (e.g., radio signals) in air at such high frequencies. Due to the shorter wavelength of the high frequency signals, a large number of small antenna arrays can be used to enable the beamforming technique to achieve a more accurate beam direction. Such narrow beam techniques can improve coverage of high frequency signals and compensate for transmission losses, which may be one of the main causes of communication system failure at such high frequencies.

With the continuous development of wireless technology, future wireless access networks are expected to be able to support the explosive growth of wireless services. To support this growing demand, various techniques such as beamforming have been further developed. These further developments in beamforming have been applied to various aspects of wireless communications, such as beamforming for uplink communications in control channels, synchronization signals and Random Access Channels (RACH).

To provide more RACH resources for a beam, the RACH preamble and its corresponding RACH format may be shortened relative to RACH formats used in previous generation wireless communication systems, such as LTE format 0/1/2/3. By shortening the RACH preamble sequence, the RACH resources in the time domain (e.g., more RACH resources per unit time) may be increased. A shorter preamble sequence may be achieved by having a larger subcarrier spacing. For example, 15/30/60/120 kilohertz (kHz) subcarrier spacing may be used for RACH symbols, which may be different from 1.25kHz subcarrier spacing that may be used for long term evolution. The increase in subcarrier spacing does not adversely affect wireless traffic because the 5G NR can provide a wider carrier bandwidth. Another reason for using 15/30/60/120kHz subcarrier spacing for RACH symbols (e.g., symbols of the RACH preamble) may be to match the subcarrier spacing of data and control channels. When the RACH symbols and the data or control channels use the same subcarrier spacing, interference of the RACH symbols on the data and control channels can be mitigated.

The configuration of the short preamble sequence is shown in table 1 below:

table 1: preamble format for short prefix sequences

Referring to table 1, a path profile Ts may characterize a multi-path delay from a User Equipment (UE) to a Base Station (BS). Such multipath delays may be caused by the surrounding environment of the wireless signal (e.g., a hill) reflecting the wireless signal to cause a delay relative to the line-of-sight wireless signal. The path profile (us) may be expressed in increments of 1/30.72MHz of base unit. Furthermore, the boundaries of RACH preamble (or physical random access channel Preamble (PRACH)) symbols may be aligned with Orthogonal Frequency Division Multiplexing (OFDM) symbol boundaries of data (in a data channel or a control channel) having the same set of parameters (e.g., for the corresponding symbols). For each short preamble sequence of table 1, an additional 16Ts every 0.5 milliseconds (ms) may be included in the cyclic prefix time TCP when the RACH preamble is transmitted on or from a 0.5ms boundary. For preamble format a, the guard interval (GP) may be within the last RACH preamble of the continuously transmitted RACH preambles. Further, for 30/60/120kHz subcarrier spacing, the preamble format may be scaled according to the subcarrier spacing. For example, for a 30kHz subcarrier spacing, Ts is 1/(2 × 30720) ms; for a 60kHz subcarrier spacing, Ts is 1/(4 × 30720) ms; for 120kHz subcarrier spacing, Ts is 1/(8 × 30720) ms. Thus, some formats may not be applicable to all subcarrier spacings.

Referring to format a of table 1, a subcarrier spacing of Physical Uplink Shared Channel (PUSCH) and/or Physical Uplink Control Channel (PUCCH) symbols may be the same as a subcarrier spacing of corresponding RACH symbols (e.g., at 15 kHz). Thus, for format a, the RACH preamble may be aligned with the OFDM symbol boundary for data with the same set of parameters. In other words, the OFDM symbol boundaries reserved for PUSCH/PUCCH symbols may be the same as the boundaries reserved for RACH symbols. Such alignment may allow a Base Station (BS) to receive symbols from the RACH preamble, the common synchronization code, and the common synchronization code using the same receive beam. Furthermore, all cyclic prefixes of PUSCH or PUCCH OFDM symbols may be grouped together and consistent with the RACH preamble as the only cyclic prefix of the RACH preamble.

Fig. 1A is a block diagram illustrating an exemplary relationship between a Physical Uplink Shared Channel (PUSCH) or Physical Uplink Control Channel (PUCCH) symbol without delay and a Random Access Channel (RACH) preamble according to format a 1. The BS may utilize two receive beams, a first receive beam 102A and a second receive beam 102B. A receive beam may refer to a beam received (e.g., detected) at an antenna configuration, such as a beam received at a BS from a UE. The cyclic prefix 103 of the RACH preamble 104 may be 288 samples in length, which may be equal to the total number of samples of the cyclic prefixes of the two PUSCH symbols 106A and 106B (e.g.,

cyclic prefixes

105A and 105B, each having 144 samples). Thus, RACH preamble boundaries (e.g., start and end points) may be aligned with the boundaries of the corresponding two PUSCH symbols 106A and 106B.

However, a delay may occur in a radio signal due to a propagation time of an electric wave signal or transmission between the BS and the UE. This type of delay may be referred to as a "round trip delay," or more simply, a "delay. The round trip delay may reflect how time is required for a wireless signal to propagate (e.g., transmit) from the BS to the UE and from the UE back to the BS.

Fig. 1B is a block diagram 120 illustrating round trip delay. Block diagram 120 shows the timing between Uplink (UL) and downlink (downlink) signals as signal stream 122B received at BS 122A, UE and signal stream 122C received at the BS. A signal stream may refer to the timing and boundaries of a signal. Ideally, without delay, the transmitted signal streams would be aligned (e.g., the signal streams at the BS and the received signal streams at the BS would be aligned). However, due to the distance between devices through which the signal propagates, the signal delay caused by the propagation time of the electric wave signal can be calculated as d/c, where d is the distance between the BS and the UE and c is the speed of light. Thus, the downlink signal received at the UE from the BS may have some amount of delay, as reflected by the UE in the received signal stream 122B. Furthermore, the uplink signal received by the BS from the UE may also add the same specific amount of delay, as reflected by the BS in the received signal stream 122C. The combination of the amount of delay between uplink and downlink communications may be referred to as the round trip delay 124. This round-trip delay may be exacerbated as the cell radius becomes larger and/or the UE location becomes more distant.

Due to round trip delay, the RACH preamble may not be aligned with the OFDM symbol boundary of the data, especially when the UE is far away from the base station. Such misalignment may result in incomplete accumulation of preamble sequence energy (e.g., radio frequency signals) within one beam duration, resulting in the base station missing a RACH preamble due to partial detection of the RACH preamble. Fig. 1C is a block diagram 160 showing how round trip delay may interfere with random access communications. The delay 162 (e.g., radio signal propagation delay) of the RACH preamble 164 of a remote UE (e.g., a UE near the edge of a BS cell) may misalign the detection duration (e.g., 4384 samples) of the receive

beams

166A and 166B at the BS (e.g., an antenna configuration for receiving a particular signal) with the duration of the RACH preamble 164. Furthermore, due to delay 162, a single symbol may not fall within the expected symbol length of 2048 sample points to align with a particular receive beam. Taking first RACH symbol 168A as an example, detection of first RACH symbol 168A using first receive beam 166A may fail because first RACH symbol 168A may not fall within the samples of first beam 166A. Therefore, the BS may not be able to correctly detect and receive all symbols 168A of the RACH preamble 164 of the remote UE. (at least because it does not fall within the detection duration of receive beam 166A of the BS). Further, the delay 162 may offset the RACH preamble 164 of the remote UE such that it may spread 170 and interfere with signals following the RACH preamble 164 of the remote UE. In some embodiments, the symbols 168A and 168B may be the same symbol. Thus, for receive beam 166B, symbol 168B may be detected as a combination of the terminal portion of symbol 168A and the initial portion of symbol 168B within the sample point covered by receive beam 166B. In contrast, the RACH preamble 172 of a neighboring UE (e.g., a UE in the vicinity of the relevant BS) may not actually be affected by the delay 162 (e.g., may not have the delay 162 of the RACH preamble of the far-end UE). Thus, the RACH preamble 172 of the neighboring UE may not have the negative effects of delay 162, such as symbol detection failure and spreading signals after the RACH preamble 172 of the interfering neighboring UE.

These negative effects may be even more severe if the RACH preamble has no guard interval. For example, referring to table 1, the preamble formats of a0-A3, B0, C0, and C1 may have no guard interval (e.g., the guard interval time TGP is zero). Thus, any delay results in a corresponding spreading, interfering with the signals following the RACH preamble in the RACH preamble formats of a0-A3, B0, C0 and C1. While the signal after the delayed RACH preamble may have a cyclic prefix to prevent such interference spreading, such cyclic prefix may not be long enough (e.g., more than 140 or 160 samples) to avoid the spread interference caused by the delay. Furthermore, positioning the UE near the BS, or shrinking the cell radius, may unnecessarily increase the overhead of the wireless communication system. Thus, conventional techniques for RACH preamble format and transmission may not be entirely satisfactory.

Disclosure of Invention

The exemplary embodiments disclosed herein are intended to solve the problems associated with one or more of the problems presented in the prior art, as well as to provide additional features that will become apparent by reference to the following detailed description in conjunction with the accompanying drawings. In accordance with various embodiments, exemplary systems, methods, devices, and computer program products are disclosed herein. It is to be understood, however, that these embodiments are given by way of illustration and not of limitation, and that various modifications to the disclosed embodiments may be apparent to those skilled in the art upon reading this disclosure while remaining within the scope of the invention.

In one embodiment, a method performed by a first communication node comprises: identifying a Random Access Channel (RACH) preamble set comprising: at least one RACH preamble comprising at least one symbol, each symbol having a predetermined length; and a RACH preamble cyclic prefix for each RACH preamble, each RACH preamble cyclic prefix having a length equal to a combined length of a plurality of first cyclic prefixes, each first cyclic prefix being associated with a respective first symbol; and transmitting a set of RACH preambles having a time advance offset length between the shortest first cyclic prefix length and a combined length of the plurality of first cyclic prefixes.

In another embodiment, a method performed by a first communication node comprises: receiving, from a second communication node, a Random Access Channel (RACH) preamble set having a time advance offset length between a shortest first cyclic prefix length and a combined length of a plurality of first cyclic prefixes, the RACH preamble set comprising: at least one RACH preamble comprising at least one symbol, each symbol having a predetermined length; and a RACH preamble Cyclic Prefix (CP) for each RACH preamble, each RACH preamble cyclic prefix having a length equal to a combined length of a plurality of first cyclic prefixes, each first cyclic prefix associated with a respective first symbol; and transmitting a random access response involving the at least one RACH preamble to the second communication node.

In another embodiment, the first communication node comprises: at least one processor configured to: identifying a Random Access Channel (RACH) preamble set comprising: at least one RACH preamble comprising at least one symbol, each symbol having a predetermined length; and a RACH preamble cyclic prefix for each RACH preamble, each RACH preamble cyclic prefix having a length equal to a combined length of a plurality of first cyclic prefixes, each first cyclic prefix being associated with a respective first symbol; and a transmitter configured to: transmitting a set of RACH preambles having a time advance offset length between a shortest first cyclic prefix length and a combined length of the plurality of first cyclic prefixes.

In yet another embodiment, the first communication node comprises: a receiver configured to: receiving a Random Access Channel (RACH) preamble set from a second communication node, the random access channel preamble set having a time advance offset length between a shortest first cyclic prefix length and a first cyclic prefix length, the RACH preamble set comprising: at least one RACH preamble comprising at least one symbol, each symbol having a predetermined length; and a RACH preamble Cyclic Prefix (CP) for each RACH preamble, each RACH preamble CP having a length equal to a combined length of a plurality of first cyclic prefixes, each first cyclic prefix being associated with a respective first symbol; a transmitter configured to: transmitting a random access response involving the at least one RACH preamble to the second communication node.

Drawings

Various exemplary embodiments of the present invention are described in detail below with reference to the accompanying drawings. The drawings are provided for purposes of illustration only and merely depict exemplary embodiments of the invention to facilitate the reader's understanding of the invention. Accordingly, the drawings are not to be considered limiting of the breadth, scope, or applicability of the present invention. It should be noted that for clarity and ease of illustration, the drawings are not necessarily drawn to scale.

Fig. 1A is a block diagram illustrating an exemplary relationship between Physical Uplink Shared Channel (PUSCH) or Physical Uplink Control Channel (PUCCH) symbols and a non-delayed Random Access Channel (RACH) preamble.

Fig. 1B is a block diagram illustrating round trip delay.

Fig. 1C is a block diagram illustrating how round trip delay may interfere with random access communications.

Fig. 2 illustrates an exemplary cellular communication network in which techniques disclosed herein may be implemented, according to some embodiments of the invention.

Fig. 3 is a block diagram illustrating an exemplary Base Station (BS) and User Equipment (UE) in accordance with some embodiments of the present invention.

Fig. 4 is a block diagram illustrating advancing a RACH preamble in accordance with some embodiments of the present invention.

Fig. 5 is a block diagram illustrating an early RACH preamble with different lengths of time advance offset and guard interval in accordance with some embodiments of the present invention.

Fig. 6 is a block diagram illustrating a pre-RACH preamble during a beam sweep with four symbols in accordance with some embodiments of the present invention.

Fig. 7 is a block diagram illustrating a pre-RACH preamble during coverage enhancement according to some embodiments of the present invention.

Fig. 8 is a block diagram illustrating a pre-RACH preamble with digital beamforming or independent Radio Frequency (RF) chain in accordance with some embodiments of the present invention.

Fig. 9 is a block diagram illustrating a RACH preamble set with a time advance offset in accordance with some embodiments of the present invention.

Detailed Description

Various exemplary embodiments of the invention are described below with reference to the drawings to enable one of ordinary skill in the art to make and use the invention. It will be apparent to those skilled in the art upon reading this disclosure that various changes or modifications can be made to the examples described herein without departing from the scope of the invention. Accordingly, the present invention is not limited to the exemplary embodiments and applications described and illustrated herein. Additionally, the particular order or hierarchy of steps in the methods disclosed herein is merely exemplary. The particular order or hierarchy of steps in the methods or processes disclosed may be rearranged while remaining within the scope of the present invention. Accordingly, one of ordinary skill in the art will understand that the methods and techniques disclosed herein present the various steps or actions in a sample order, and the invention is not limited to the specific order or hierarchy presented unless specifically indicated otherwise.

As described below, the following discussion may refer to functional entities, e.g., BSs, UEs, cells, etc. (in physical or virtual form), which are similar to the entities mentioned above with respect to conventional communication systems. However, as will be appreciated by one of ordinary skill in the art, such conventional functional entities do not perform the functions described below and, therefore, would require modification or specialized configuration to perform one or more of the operations described below. In addition, after reading this disclosure, one of ordinary skill in the art will be able to configure the functional entities to perform the operations described herein. The term "configured" as used herein with respect to a particular operation or function refers to a system, device, component, circuit, structure, machine, etc. Physically or virtually constructed, programmed and/or arranged to perform the specified operations or functions.

Fig. 2 illustrates an example wireless communication network 200 in which the techniques disclosed herein may be implemented, in accordance with embodiments of the present disclosure. Exemplary communication network 200 may cover a geographic area 201 and may include a Base Station (BS)202 and a User Equipment (UE) device 204 capable of communicating with each other via a communication link 210 (e.g., a wireless communication channel), and a set of

conceptual cells

226, 230, 232, 234, 236, 238, and 240. In fig. 2, BS 202 and UE 204 are contained within the geographic boundaries of cell 226. Each of the

other cells

230, 232, 234, 236, 238 and 240 may include at least one Base Station (BS) operating at its allocated bandwidth to provide sufficient wireless coverage for its intended users. For example, the BS 202 may operate at the allocated channel transmission bandwidth to provide sufficient coverage to the UE 204. BS 202 and UE 204 may communicate via downlink radio frames 241 and uplink radio frames 243, respectively. Each radio frame 245/247 may be further divided into subframes 249/251, which may include data symbols 253/255.

In the present disclosure, a Base Station (BS)202 and a User Equipment (UE)204 are described herein as non-limiting examples of "communication nodes," which may practice the methods disclosed herein in general. Such a communication node may be capable of wireless and/or wired communication in accordance with various embodiments of the present invention. Each of these communication nodes may be a transmitter in one case and a receiver in another case. For example, the BS 202 may transmit to the UE 204, e.g., during the downlink (D1), which will be discussed further below. Thus, the BS 202 may be a transmitter and the UE 204 may be a receiver. However, in another case, such as in the Uplink (UL), which will be described further below, the UE 204 may be a transmitter and the BS 202 may be a receiver. Thus, as will be discussed further below, both the BS 202 and the UE 204 may be receivers or transmitters for advancing random access preamble transmissions.

In network 200, signals transmitted from BS 202 may be subject to environmental and/or operating conditions that result in undesirable channel characteristics, such as doppler spread, doppler shift, delay spread, multipath interference, and the like, as described above. For example, the multipath signal components may be the result of reflections, scattering and diffraction of the transmitted signal by natural and/or man-made objects. At the receiver antenna 114, a large number of signals may arrive from many different directions with different delay times, attenuations, and phases. In general, the time difference between the arrival times of the first received multipath component (typically the line-of-sight component) and the last received multipath component (typically the non-line-of-sight (NLOS) component) is referred to as the delay spread. The combination of signals having different delay times, attenuations, and phases may produce distortions in the received signal, such as inter-symbol interference (ISI) and inter-channel interference (ICI). Distortion may complicate the reception and conversion of the received signal into useful information. For example, delay spread may cause ISI in the useful information (data symbols) contained in radio frame 224.

Fig. 3 shows a block diagram of an exemplary system 300, the exemplary system 300 including a Base Station (BS)302 and a User Equipment (UE)304 for transmitting and receiving wireless communication signals (e.g., OFDM/OFDMA signals) between each other. System 300 may include components and elements configured to support known or conventional operating features, which need not be described in detail herein. In one exemplary embodiment, as described above, system 300 can be employed to transmit and receive data symbols in a wireless communication environment, such as wireless communication environment 200 of fig. 1.

The BS 302 includes a BS transceiver module 310, a BS antenna 312, a BS processor module 314, a BS memory module 316, and a network communication module 318, each coupled and interconnected with each other as needed via a data communication bus 320. The UE 304 includes a UE transceiver module 330, a UE antenna 332, a UE memory module 334, and a UE processor module 336, each coupled and interconnected with each other as needed through a data communication bus 340. The BS 302 communicates with the UE 304 via a communication channel (e.g., link) 350, which communication channel 350 may be any wireless channel or other medium known in the art suitable for data transmission as described herein.

As one of ordinary skill in the art will appreciate, the system 300 may further include any number of modules other than those shown in fig. 2. Those of skill in the art will appreciate that the various illustrative blocks, modules, circuits, and processing logic described in connection with the embodiments disclosed herein may be implemented as hardware, computer readable software, firmware, or any practical combination thereof. To clearly illustrate this interchangeability and compatibility of hardware, firmware, and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware, firmware, or software depends upon the particular application and design constraints imposed on the overall system. Persons familiar with the concepts described herein may implement such functionality in an appropriate manner for each particular application, but such implementation decisions should not be interpreted as limiting the scope of the present invention.

The UE transceiver 330 may be referred to herein as an "uplink" transceiver 330, which includes RF transmitter and receiver circuits each coupled to an antenna 332, according to some embodiments. A duplex switch (not shown) may alternatively couple the uplink transmitter or receiver to the uplink antenna in a time-duplex manner. Similarly, BS transceiver 310 may be referred to herein as a "downlink" transceiver 310, according to some embodiments, which includes RF transmitter and receiver circuits that are each coupled to an antenna 312. The downlink duplex switch may optionally couple a downlink transmitter or receiver to the downlink antenna 312 in a time-duplex manner. The operation of the two

transceivers

310 and 330 is coordinated in time so that while the downlink transmitter is coupled to the downlink antenna 312, the uplink receiver is coupled to the uplink antenna 332 for receiving transmissions over the wireless transmission link 350. Preferably, there is only a minimum guard time between changes in the duplex direction for tight time synchronization.

The UE transceiver 330 and the base station transceiver 310 are configured to communicate via a wireless data communication link 350 and cooperate with a suitably configured RF antenna arrangement 312/332 that is capable of supporting particular wireless communication protocols and modulation schemes. In some demonstrative embodiments, UE transceiver 608 and base station transceiver 310 are configured to support industry standards, such as Long Term Evolution (LTE) and the emerging 5G and New Radio (NR) standards. It should be understood, however, that the present invention is not necessarily limited to the application of a particular standard and associated protocol. Rather, the UE transceiver 330 and the base station transceiver 310 may be configured to support alternative or additional wireless data communication protocols, including future standards or variants thereof.

According to various embodiments, the base station 302 may be, for example, a next generation nodeB (gbnodeb or gNB), a serving gbb, a target gbb, a Transmit Receive Point (TRP), an evolved nodeB (eNB), a serving eNB, a target eNB, a femto station, or a pico station. In some embodiments, the UE 304 may be embodied in various types of user equipment, such as a mobile phone, a smartphone, a Personal Digital Assistant (PDA), a tablet, a laptop, a wearable computing device, and so forth. The

processor modules

314 and 336 may be implemented or realized with a general purpose processor, a content addressable memory, a digital signal processor, an application specific integrated circuit, a field programmable gate array, any suitable programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof, designed to perform the functions described herein. In this manner, the processor may be implemented as a microprocessor, controller, microcontroller, state machine, or the like. A processor may also be implemented as a combination of computing devices, e.g., a combination of a digital signal processor and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a digital signal processor core, or any other such configuration.

Furthermore, the steps of a method or algorithm described in connection with the embodiments disclosed herein may be embodied directly in hardware, in firmware, in a software module executed by the

processor modules

314 and 336, respectively, or in any practical combination thereof.

Memory modules

316 and 334 may be implemented as RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. In this regard, the

memory modules

316 and 334 may be coupled to the

processor modules

314 and 336, respectively, such that the

processor modules

314 and 336 may read information from the

memory modules

316 and 334 and write information to the

memory modules

316 and 334, respectively.

Memory modules

316 and 334 may also be integrated into their

respective processor modules

314 and 336. In some embodiments,

memory modules

316 and 334 may each include a cache memory for storing temporary variables or other intermediate information during execution of instructions to be executed by

processor modules

314 and 336, respectively. The

memory modules

316 and 334 may also each include non-volatile memory for storing instructions to be executed by the

processor modules

314 and 336, respectively.

The network communication module 318 generally represents the hardware, software, firmware, processing logic, and/or other components of the base station 302 that enable bi-directional communication between the base station transceiver 310 and other network components and communication nodes configured to communicate with the base station 302. For example, the network communication module 318 may be configured to support internet or WiMAX services. In a typical deployment, but not limited to, the network communication module 318 provides an 802.3 ethernet interface so that the base station transceiver 310 can communicate with a conventional ethernet-based computer network. In this manner, the network communication module 318 may include a physical interface (e.g., a Mobile Switching Center (MSC)) for connecting to a computer network.

To meet the performance requirements of International Mobile Telecommunications (IMT) Advanced systems, the LTE/LTE-Advanced standard has provided several features to optimize wireless networks in the frequency, time, and/or spatial domains. With the continuous development of wireless technology, future wireless access networks are expected to be able to support the explosive growth of wireless services. Among these features, expanding the system bandwidth is a simple method of improving link and system capacity, which has been tested and confirmed by deploying carrier aggregation in LTE-Advanced systems.

As the demand for capacity increases, the mobile industry and academia are increasingly interested in increasing the system bandwidth above 100 MHz. Furthermore, as the spectrum resources operating at frequencies below 6GHz become more crowded, high frequency communications above 6GHz are well suited to support system bandwidths in excess of 100MHz, and even up to 1 GHz.

In some embodiments, communication between the base station and the UE is implemented with signal frequencies greater than 6GHz, which is also referred to as "millimeter wave communication. However, high operating frequencies (i.e., greater than 6GHz) can result in significant propagation losses when using broad spectrum or ultra-wide spectrum resources. To solve this problem, antenna arrays (e.g., panel arrays) and Beamforming (BF) training techniques using massive MIMO have been adopted, for example, 1024 antenna elements are adopted for one node to achieve beam alignment and obtain sufficiently high antenna gain. To benefit from antenna array technology while reducing costs, analog phase shifters have become attractive for implementing millimeter wave Beamforming (BF), which means that the number of phases is limited, and other constraints (e.g., amplitude constraints) may be placed on the antenna elements to provide variable phase shift based BF. In view of such pre-specified beam patterns (e.g., Antenna Weight Vector (AWV) codebooks), a variable phase shift-based BF training target for identifying the best N beams for subsequent data transmission may be determined.

Misalignment between transmit (Tx) and receive (Rx) beams may result in a significant loss of receive power, especially for systems with narrow beams. Beam alignment can be used to find the best beam pair from all possible beam pairs to obtain the maximum beamforming efficiency. The best beam pair may be determined by selecting the beam pair with the largest array gain. Random access may be used to initiate communication and alignment between the user UE and the BS. For example, in random access, a preamble (e.g., RACH preamble or PRACH preamble) may be a kind of logical resource repeatedly transmitted/received from a UE and a BS in multiple directions to synchronize and align a user equipment and a base station. A single transmit beam may be transmitted by the UE until all transmit (Tx) beams are transmitted. A receiver (Rx) beam sweep may be performed at the BS for each transmit beam to measure the signal-to-noise ratio (SNR) for each Tx-Rx pair.

Random access is typically performed when a UE is turned on from a sleep mode, performs a handover (handover) from one cell to another, or loses uplink time synchronization. As part of random access, the UE may receive signals (e.g., synchronization signals and/or reference signals) and/or share channels (e.g., broadcast channels and/or shared channels) with the BS. Information from these signals and/or channels may indicate (e.g., inform or inform) how the UE communicates with the BS in random access. Based on information in the synchronization signal and/or the reference signal, the UE may transmit a preamble to the BS. When the BS successfully receives the preamble, the BS may transmit a random access response to the UE, the random access response indicating the preamble index, the uplink timing advance, and the uplink resource allocation information. Based on the random access response, the UE may determine whether its random access attempt is successful by matching the preamble index with the preamble transmitted by the UE to the BS. If there is a match, the UE may use the TA information to adjust its uplink timing and send a random access message including the UE's identity in the resource allocation according to the uplink resource allocation information.

Systems and methods in accordance with various embodiments describe advanced random access preamble transmission. The advanced random access preamble transmission may include a Random Access Channel (RACH) preamble with a time advance offset. The RACH preamble may be part of the RACH and, when considered as a physical resource, may be transmitted as part of a Physical Random Access Channel (PRACH). By having a time advance offset, the early RACH preamble can be set earlier (earlier than would be sent without the time advance offset), such as by being sent prior to initialization of the corresponding base station receive beam. Thus, the initiation of the transmission of the RACH preamble or the resource associated with the RACH preamble may not necessarily coincide in time with the initiation of the reception procedure of the RACH preamble (e.g., the base station receive beam). In other words, the OFDM symbol boundary alignment of data with the same set of parameters (e.g., synchronized data streams between the transmitter and receiver) may be advanced (e.g., transmitted in advance and not aligned) at the time of UE transmission (e.g., for an advanced RACH preamble) and not advanced (e.g., not transmitted in advance) for BS transmission. Further, in some embodiments, the early RACH preamble may also include an early guard interval following the RACH preamble to avoid interfering with signals following the early RACH preamble.

Advantageously, by transmitting earlier, the early RACH preamble may have time-early offset symbols that counteract the negative effects of delay, such as symbol detection failure and spreading interference to signals following the RACH preamble as described above. Further, the early RACH preamble can be characterized by a guard interval (e.g., an early guard interval) following the at least one early RACH preamble. The advanced guard interval may further prevent the negative effects of delay by preventing extended interference from advancing the signal after the RACH preamble as additional buffering. Furthermore, by having an early guard interval, the time advance offset need not be the only parameter that can be changed to counteract the negative effects of delay. In some embodiments, the advanced guard interval may be a byproduct of the time advance offset and may not be applied without applying the time advance offset.

The RACH preamble may be particularly suitable for featuring a time advance offset. For example, the RACH preamble may be transmitted without a previous signal (e.g., a signal also transmitted from the UE before the UE transmits the early RACH preamble). This may be applicable in certain situations, such as, for example, when initializing random access, when the UE turns on from sleep mode. Thus, advancing the RACH preamble (e.g., transmitting it earlier) does not affect any previous signals (since there may be no previous signals transmitted from the UE). Further, as another example, the previous signal may have a sufficiently large guard interval such that advancing the RACH preamble may advance (e.g., offset) to the guard interval of the previous signal without causing undesirable interference to the previous signal. Furthermore, in various embodiments, the advanced RACH preamble with time advance offset may start in a normal time slot or subframe and is not limited to a particular time slot consisting of downlink symbols and uplink symbols. Thus, the early RACH preamble may not need to occupy the guard interval between uplink and downlink symbols.

As will be discussed further below, the time advance offset may have various different lengths as required by different applications in different embodiments. For example, in some embodiments, the length of the time advance offset may range from the cyclic prefix length of the standard data symbols (e.g., standard data symbol cyclic prefix length) to the cyclic prefix length of the advanced RACH preamble. The standard data symbol may refer to the length of a data symbol, such as a data symbol in a PUSCH or PUCCH, or any type of control, data, broadcast, or shared channel. Each standard data symbol may have an associated cyclic prefix. A cyclic prefix may refer to a prefix of a symbol with a repetition of the end of the symbol.

In particular embodiments of beam scanning scenarios (e.g., with different BS receive beams), the time advance offset length may be less than the length of the cyclic prefix of the advanced RACH preamble. For example, the time advance offset length may be a standard data symbol cyclic prefix length, or may be 1/N of the advance RACH preamble cyclic prefix length, where N is an integer (and is selected based on a desired proportion (e.g., 1/N value) of the advance RACH preamble cyclic prefix length). In other embodiments of the coverage enhancement scenario (e.g., with uniform or identical BS receive beams), the time advance offset length may be an advance RACH preamble cyclic prefix length.

In certain embodiments, the configuration of the early RACH preamble (e.g., the time advance offset length and/or the value of the early guard interval) may be determined in RACH configuration signaling, e.g., in RMSI (remaining system information) by static or semi-static methods. These methods may be based on the scenario in which the base station is selected, e.g., whether there is beam scanning or coverage enhancement at the base station, and/or whether there is particular beam processing capability at the base station. In further embodiments, the configuration of the advanced RACH preamble (e.g., the time advance offset length and/or the value of the advanced guard interval) may be predefined in a communication specification for the UE and/or the BS.

In particular embodiments, when multiple advanced RACH preambles are concatenated end-to-end in one time slot (e.g., when multiple advanced RACH preambles are transmitted consecutively together), the same time advance offset (e.g., time advance) may be applied to all of the multiple concatenated advanced preambles. The advanced RACH preambles (e.g., formats of the advanced RACH preambles) may be used by only one UE or by a plurality of different UEs when communicating with the BS.

Fig. 4 is a block diagram illustrating an early RACH preamble 402 with a time advance offset in accordance with some embodiments of the present invention. The early RACH preamble 402 may include two symbols 404A and 404B, and an early RACH cyclic prefix 406. The length (e.g., duration or time domain resource allocation) of the early RACH cyclic prefix 406 may be the same as the sum of the cyclic prefix lengths of an equivalent number of corresponding data symbols. For example, the early RACH preamble 402 may have symbols 404A and 404B of the same length as the corresponding data symbols 408A and 408B. Further, the early RACH preamble 402 may have a cyclic prefix 406, the cyclic prefix 406 having the same length as the sum of the cyclic prefixes 410A and 410B associated with the respective data symbols 408A and 408B. As described above, these data symbols 408A and 408B may be part of the PUSCH or PUCCH. Further, BS receive

beams

412A and 412B may be aligned with (e.g., configured to sample within the time resources allocated to them) each pair of data symbols 408A or 408B and corresponding cyclic prefix 410A or 410B.

It may be noted that the BS (e.g., BS receive

beams

412A and 412B) may not necessarily receive (e.g., process) the entire early RACH cyclic prefix 406 length of 288 samples. Conversely, the BS may only need to receive the partial RACH cyclic prefix 406 to process the early RACH preamble 402 as long as the required number of samples (e.g., 2048 samples of symbols 404A or 404B) are detected. For example, point a may refer to the latest point in time at which the first receive beam 412A may begin processing (e.g., receiving) the advanced RACH preamble 402 in order to fully process the advanced RACH preamble 402 (e.g., process the symbols 404A, 404B of the advanced RACH preamble 402). Specifically, point a may refer to 144 samples of the advanced RACH preamble cyclic prefix 406 (e.g., 144 samples after the start of the advanced RACH preamble cyclic prefix 406).

Thus, the time advance offset 414 that advances the RACH preamble 402 may be 144 samples. By advancing 144 samples, the receive

beam

412A or 412B can detect the corresponding RACH preamble symbol 404A and 404B as a set of 2048 samples (e.g., the number of samples of a single symbol) without creating an extension of the advanced RACH preamble 402 that would interfere with subsequent signals (e.g., interfere with subsequent time slots). For example, the set of 2048 samples may be all of each of the early RACH preamble symbols 404A and 404B, a combination of a portion of the early RACH cyclic prefix 406 and a portion of the symbol 404A, or a combination of a portion of the symbol 404A and a portion of the symbol 404B.

As described above, when the UE is close to the BS, there may be a null value (e.g., zero) or a minimum round trip delay. By having a round trip delay of null value, the base station reception time can be practically identical to the time of UE transmission. Thus, the early RACH preamble 402A transmitted from a UE in proximity to the BS (e.g., early RACH preamble 402A of a nearby UE) may have a symbol boundary (e.g., symbol boundary B) that is substantially aligned between the early RACH preamble symbol 404A and the data symbol 408A. Further, from line a to line B, the detection window of the first receive beam 412A may be 2192 samples, sufficient to cover (e.g., completely overlap and detect) the first early RACH preamble symbol 404A. Further, due to the time advance offset 414, an advance guard interval 416 is automatically generated at the end of the advance RACH preamble 402A, which may provide further buffering (e.g., protection) for subsequent or subsequent signals (e.g., next slot data).

When the UE is far away from the BS (e.g., near the cell edge of a relatively large cell), there may be a non-negligible round trip delay 420 of approximately 288 sampling points. However, due to the time advance offset consistent with the advance RACH preamble 402B transmitted from the UE far away from the BS (e.g., the advance RACH preamble 402B of the far-end UE), the detection window of the first BS receive beam 412A may be sufficient to cover (e.g., completely overlap and detect) the first advance RACH preamble symbol 404A. This can be shown in the time domain resource window between line C and line D. The time domain resource window (within the time domain resources coinciding with the first receive beam 412A) may be 2048 samples. The delay 420 may extend the early RACH preamble 402B into a time resource reserved for a subsequent or subsequent signal (e.g., the next slot). However, the spreading amount (e.g., 144 samples) may be within the cyclic prefix of the subsequent signal (e.g., the next slot) and may not undesirably interfere with the encoded data of the subsequent signal (e.g., the next slot).

The time advance offset may have various lengths as desired for different applications in different embodiments. The value (e.g., amount or length) of the time advance offset may affect whether the symbols of the advanced RACH preamble 402 are fully (e.g., correctly) detected by the receive beam of the BS. For example, if the time advance offset is less than 144 samples and the round trip delay is 288 samples, the first receive beam 412A may not be able to fully detect the first advanced RACH preamble symbol 404A and the advanced RACH preamble may spread and cause undesirable interference to subsequent signals (e.g., signals within the next time slot). However, if the time advance offset is greater than 144 samples, the second receive beam 412B may not be able to fully detect the second RACH preamble symbol 404B.

Thus, in some embodiments, the length of the time advance offset may range from the length of the cyclic prefix of the standard data symbol (e.g., cyclic prefix 410A) to the length of the cyclic prefix of the advanced RACH preamble (e.g., cyclic prefix 406). Considering that the round trip delay may vary and may not always be a maximum value (where the maximum value is 288, or twice the length of the cyclic prefix of a standard data symbol), a time advance offset that is less than the cyclic prefix of a standard data symbol may result in a performance loss. Thus, in some embodiments, the time advance offset length may be a fraction of the advance RACH preamble cyclic prefix length, or 1/N of the advance RACH preamble cyclic prefix length, where N is an integer. N may be selected based on a desired proportion (e.g., 1/N value) of the advanced RACH preamble cyclic prefix length.

Fig. 5 is a block diagram illustrating a RACH preamble 502 with different lengths of time advance offset 504 and guard interval 506 in accordance with some embodiments of the present invention. In some embodiments, the cyclic prefix lengths (e.g., cyclic prefixes 508A and 508B) of particular data symbols (e.g., data symbols 510A and 510B) may be different. For example, when the first data symbols are at the 0.5 millisecond (ms) boundary, they may not be fixed at 144 sample points (e.g., at cyclic prefix 508B), but may also be 160 sample points (e.g., at cyclic prefix 508A). This may occur with a subcarrier spacing equal to 15 kilohertz (kHz) and a sampling rate of 30.72 megahertz (MHz). When the early RACH preamble 502 begins from a 0.5ms boundary, the time advance offset 504 may not be the longer of the cyclic prefix lengths of the data symbols (e.g., cyclic prefix 508A), but the normal (e.g., shorter or most common) of the cyclic prefix lengths of the following data symbols (e.g., cyclic prefix 508B).

Fig. 6 is a block diagram illustrating an early RACH preamble 602 during a beam sweep with four symbols in accordance with some embodiments of the present invention. The early RACH preamble 602 may include four

symbols

604A, 604B, 604C, and 604D, and an early RACH cyclic prefix 606. The early RACH cyclic prefix 606 may have a length that is the same as the sum of the cyclic prefix lengths of an equivalent number of corresponding data symbols. For example, the early RACH preamble 602 may have symbols 604A-604D of the same length as the corresponding data symbols 608A-608D. Further, the early RACH preamble 602 may have a cyclic prefix 606, the cyclic prefix 606 having the same length as the sum of the cyclic prefixes 610A-610D associated with the respective data symbols 608A-608D. As described above, these data symbols 608A-608D may be part of a PUSCH or PUCCH. Further, base station receive beams 612A-612D can be aligned with (e.g., configured to sample within the time resources allocated to them) each pair of data symbols 608A-608D and corresponding cyclic prefixes 610A-610D. As described above, by being in a beam scanning scenario, each BS receive beam 612A-612B may be different. Thus, in a beam-sweeping scenario, the early RACH preamble may be aligned with the OFDM symbol boundary of data signals having the same set of parameters (e.g., as a synchronous data stream between the transmitter and the receiver). In some embodiments, the time advance offset length may be less than the length of the cyclic prefix of the advanced RACH preamble. For example, the time advance offset 614 may be the length of the cyclic prefix of a standard data symbol (e.g., the length of one of the cyclic prefixes 610A-610D) to handle the maximum delay that is the length of two standard data symbol cyclic prefixes. Thus, at maximum delay, the first receive beam 612A may detect the first symbol 604A by detecting a first portion of the first symbol 604A and the cyclic prefix 606 (where the cyclic prefix 606 includes a copy of a latter portion of the first symbol 604A). Fig. 7 is a block diagram illustrating a preamble RACH preamble 702 in advance of a coverage enhancement period in accordance with some embodiments of the present invention. Fig. 6 may be similar to fig. 7, except that in fig. 7, each of the receive beams 704A-704D has the same configuration, the time advance offset 706 may be longer, and the maximum delay 708 may be longer. As described above, the coverage enhancement scenario may describe that each of the receive beams 704A-704D of the BS has a uniform or same orientation. Further, each of the plurality of early RACH preamble symbols may be concatenated to improve the link budget by repeating the gain. In other words, since the reception beam of each standard data symbol (e.g., PUSCH symbol) is the same and the beams of a plurality of symbols are continuous, there may be no beam switching point between symbols. Therefore, there is no need to advance the symbol alignment of the RACH preamble 702 to any beam switching point. Therefore, it may not be necessary to advance the symbol alignment between the symbols of the RACH preamble 702 and the standard data symbols.

Further, the time advance offset 706 for the coverage enhancement scenario may be longer than the time advance offsets for other scenarios (e.g., the beam scanning scenarios of the previous figures). For example, the length of the time advance offset 706 may be an advance RACH preamble cyclic prefix length having 576 samples. A longer time advance offset 706 may result in a longer advance guard interval 710 to protect (e.g., buffer as it) signals (e.g., time slots) following the advance RACH preamble 702.

Fig. 8 is a block diagram 800 illustrating a pre-RACH preamble 802 in the context of digital beamforming or independent Radio Frequency (RF) chain, in accordance with some embodiments of the present invention. The early RACH preamble 802 may have early RACH preamble symbols 803A-803D and an early RACH preamble cyclic prefix 804. The early RACH preamble 802 may be transmitted with a time advance offset 805. The time domain resources (e.g., detection period) of BS transmit beams 806A-806D (associated with data symbols 807A-807D) may be different from BS receive beams 808A-808D (associated with early RACH preamble symbols 803A-803D).

In some embodiments, the boundaries between beams and/or between data symbols need not be aligned. In particular, alignment may not be required when performing digital beamforming, or if there are separate RF chains for the data symbols and the RACH symbols. For example, due to digital beamforming and/or a separate RF chain, the time domain resource boundaries of the BS receive beams 806A-806D need not be aligned with the BS receive beams 808A-808D for the RACH preamble for data such as PUSCH or PUSCH. Furthermore, the boundaries of the time domain resources between data symbols 807A-807D (e.g., PUSCH and/or PUUCH symbols) and RACH symbols 803A-803D (e.g., symbols of the early RACH preamble) need not be aligned. The case where the boundaries between data systems do not need to be aligned may be referred to as an alignment independent case. The time advance offset for the alignment independent case may be the same as the time advance offset for the coverage enhancement case. For example, the time advance offset length aligned to the independent case may be an advance RACH preamble cyclic prefix length.

However, in other embodiments, the time advance offset may be less than the cyclic prefix length of the advance RACH preamble due at least to the possibility of multipath delays in the advance RACH preamble or other signals in the RACH. For example, referring to table 1, when the path profile is the same as the multi-path delay, the maximum value of the path profile of the preamble format a is 144 sample points. Thus, the time advance offset length may be the advance RACH preamble cyclic prefix length minus the minimum path profile. As another example, when the number of symbols is 4 or 6, the corresponding time advance offsets may be 432 sampling points (calculated as 576-. By having a smaller time advance, symbols from a first path 820 (e.g., the signal path from the nearest UE to the BS) and a last path 822 (e.g., the signal path from the farthest UE to the BS) may be detected.

Fig. 9 is a block diagram illustrating an early RACH preamble set 902 according to some embodiments of the present invention. The set of early RACH preamble codes 902 may be a set of cascaded (e.g., consecutive, one after the other, end-to-end) early RACH preamble codes 904A and 904B. When multiple early RACH preambles 904A and 904B are concatenated end-to-end in one time slot, the same time advance offset 906 may be applied to all concatenated early RACH preambles 904A and 904B. These early RACH preambles 904A and 904B (and their associated formats) may be utilized by a single UE or by different UEs to communicate with a single BS.

While various embodiments of the present invention have been described above, it should be understood that they have been presented by way of example only, and not limitation. Likewise, the various figures may depict example architectures or configurations provided to enable one of ordinary skill in the art to understand the example features and functionality of the present invention. However, those skilled in the art will appreciate that the invention is not limited to the exemplary architectures or configurations shown, but may be implemented using a variety of alternative architectures and configurations. Furthermore, as one of ordinary skill in the art will appreciate, one or more features of one embodiment may be combined with one or more features of another embodiment described herein. Thus, the breadth and scope of the present disclosure should not be limited by any of the above-described exemplary embodiments.

It will also be understood that any reference herein to an element using a name such as "first," "second," etc., does not generally limit the number or order of those elements. Rather, these names may be used herein as a convenient means of distinguishing between two or more elements or instances of an element. Thus, reference to first and second elements does not mean that only two elements can be employed, or that the first element must precede the second element in some manner.

Further, those of ordinary skill in the art would understand that information and signals may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, and symbols (e.g., as may be referenced in the above description) may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

Those of ordinary skill would further appreciate that any of the various illustrative logical blocks, modules, processors, means, circuits, methods, and functions described in connection with the aspects disclosed herein may be implemented as electronic hardware (e.g., a digital implementation, an analog implementation, or a combination of the two), firmware, various forms of program or design code containing instructions (which may be referred to herein, for convenience, as "software" or a "software module"), or any combination of these technologies.

To clearly illustrate this interchangeability of hardware, firmware, and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware, firmware, or software, or as a combination of such technologies, depends upon the particular application and design constraints imposed on the overall system. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present disclosure. According to various embodiments, a processor, device, component, circuit, structure, machine, module, etc. May be configured to perform one or more of the functions described herein. The terms "configured" or "to" as used herein with respect to a particular operation or function refers to a processor, device, component, circuit, structure, machine, module, or the like. Which is physically constructed, programmed and/or arranged to perform the specified operations or functions.

Furthermore, those of ordinary skill in the art will appreciate that the various illustrative logical blocks, modules, devices, components, and circuits described herein may be implemented or performed within an Integrated Circuit (IC) that may include a general purpose processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other programmable logic device, or any combination thereof. The logic blocks, modules, and circuits may also include antennas and/or transceivers to communicate with various components within the network or within the device. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a digital signal processor and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a digital signal processor core, or any other suitable configuration for performing the functions described herein.

If implemented in software, the functions may be stored as one or more instructions or code on a computer-readable medium. Thus, the steps of a method or algorithm disclosed herein may be implemented as software stored on a computer-readable medium. Computer-readable media includes both computer storage media and communication media including any medium that can transfer a computer program or code from one place to another. A storage media may be any available media that can be accessed by a computer. By way of example, and not limitation, such computer-readable media can comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to store desired program code in the form of instructions or data structures and that can be accessed by a computer.

In this document, the term "module" as used herein refers to any combination of software, firmware, hardware, and the like, for performing the associated functions described herein. Further, for purposes of discussion, the various modules are described as discrete modules; however, it will be apparent to one of ordinary skill in the art that two or more modules may be combined to form a single module that performs the relevant functions according to embodiments of the present invention.

Additionally, in embodiments of the present invention, memory or other storage and communication components may be used. It will be appreciated that the above description for clarity has described embodiments of the invention with reference to different functional units and processors. It will be apparent, however, that any suitable distribution of functionality between different functional units, processing logic elements, or domains may be used without detracting from the invention. For example, functionality illustrated to be performed by separate processing logic elements or controllers may be performed by the same processing logic elements or controllers. Thus, references to specific functional units are only to references to suitable means for providing the described functionality rather than indicative of a strict logical or physical structure or organization.

Various modifications to the embodiments described in this disclosure will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the scope of the disclosure. Thus, the disclosure is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the novel features and principles as disclosed herein, as set forth in the following claims.

Claims

1. A method performed by a first communication node, the method comprising:

identifying a Random Access Channel (RACH) preamble set, the RACH preamble set comprising:

at least one RACH preamble comprising at least one symbol, each symbol having a predetermined length; and

a RACH preamble Cyclic Prefix (CP) for each RACH preamble, each RACH preamble CP having a length equal to a combined length of a plurality of first cyclic prefixes, each first cyclic prefix associated with a respective first symbol; and is

Transmitting a RACH preamble set having a time advance offset length between a shortest first cyclic prefix length and a combined length of the plurality of first cyclic prefixes.

2. The method of claim 1, wherein the RACH preamble set comprises a RACH preamble set guard interval length between a longest first cyclic prefix length and the combined length.

3. The method of claim 2, wherein the longest first cyclic prefix length and the shortest first cyclic prefix length are the same.

4. The method of claim 1, wherein the respective first symbol is associated with at least one of a Physical Uplink Shared Channel (PUSCH) and a Physical Uplink Control Channel (PUCCH).

5. The method of claim 1, wherein the value of the time advance offset length is transmitted using a first channel comprising at least one of a broadcast channel and a shared channel.

6. The method of claim 1, wherein the RACH preamble set comprises a plurality of RACH preambles.

7. The method of claim 1, wherein the time advance offset length is the shortest first cyclic prefix length.

8. The method of claim 1, wherein the time advance offset length is a combined length of the plurality of first cyclic prefixes.

9. The method of claim 1, wherein the time advance offset length is the combined length minus the shortest first cyclic prefix length.

10. The method of claim 1, wherein the time advance offset length is identified based on the respective first symbol.

11. A method performed by a first communication node, the method comprising:

receiving, from a second communication node, a Random Access Channel (RACH) preamble set having a time advance offset length between a shortest first cyclic prefix length and a combined length of a plurality of first cyclic prefixes, the RACH preamble set comprising:

a RACH preamble Cyclic Prefix (CP) for each RACH preamble, each RACH preamble CP having a length equal to a combined length of the plurality of first cyclic prefixes, each first cyclic prefix associated with a respective first symbol; and is

Transmitting a random access response involving the at least one RACH preamble to the second communication node.

12. The method of claim 11, wherein the respective first symbol is associated with at least one of a Physical Uplink Shared Channel (PUSCH) and a Physical Uplink Control Channel (PUCCH).

13. The method of claim 11, wherein the time advance offset length is the shortest first cyclic prefix length.

14. The method of claim 11, wherein the time advance offset length is a combined length of the plurality of first cyclic prefixes.

15. The method of claim 11, wherein the time advance offset length is the combined length minus the shortest first cyclic prefix length.

16. The method of claim 11, wherein the time advance offset length is identified based on the respective first symbol.

17. A first communication node, the first communication node comprising:

at least one processor configured to:

a RACH preamble Cyclic Prefix (CP) for each RACH preamble, each RACH preamble CP having a length equal to a combined length of a plurality of first cyclic prefixes, each first cyclic prefix associated with a respective first symbol; and

a transmitter configured to:

18. The first communication node of claim 17, wherein the RACH preamble set comprises a RACH preamble set guard interval length between a longest first cyclic prefix length and the combined length.

19. The first communications node of claim 17, wherein the respective first symbol is associated with at least one of a Physical Uplink Shared Channel (PUSCH) and a Physical Uplink Control Channel (PUCCH).

20. The first communication node of claim 17, wherein the time advance offset length is the shortest first cyclic prefix length.

21. The first communication node of claim 17, wherein the time advance offset length is a combined length of the plurality of first cyclic prefixes.

22. The first communication node of claim 17, wherein the time advance offset length is the combined length minus the shortest first cyclic prefix length.

23. The first communication node of claim 17, wherein the time advance offset length is identified based on the respective first symbol.

24. A first communication node, the first communication node comprising:

a receiver configured to:

a RACH preamble Cyclic Prefix (CP) for each RACH preamble, a length of each RACH preamble CP being equal to the combined length of the plurality of first cyclic prefixes, each first cyclic prefix being associated with a respective first symbol; and

a transmitter configured to:

25. The first communication node of claim 24, wherein the RACH preamble set comprises a RACH preamble set guard interval length between a longest first cyclic prefix length and the combined length.

26. The first communications node of claim 24, wherein the respective first symbol is associated with at least one of a Physical Uplink Shared Channel (PUSCH) and a Physical Uplink Control Channel (PUCCH).

27. The first communications node of claim 24, wherein said time advance offset length is said shortest first cyclic prefix length.

28. The first communication node of claim 24, wherein the time advance offset length is a combined length of the plurality of first cyclic prefixes.

29. The first communications node of claim 24, wherein said time advance offset length is said combined length minus said shortest first cyclic prefix length.

30. The first communication node of claim 24, wherein the time advance offset length is identified based on the respective first symbol.