JP6212094B2 - Random access structure for wireless networks - Google Patents

Description

  As wireless systems become pervasive, the growing user base and demand for new services requires the development of technologies that can meet the ever-increasing expectations of users. Mobile telecommunications equipment users expect a variety of data services such as email, text messaging and Internet access, as well as reliable voice communications available worldwide.

  Thus, the random access channel is intended to cover a wider range of functions than conventional or current cellular networks, thus increasing the expected load. In addition, a random access signal through which the UE initiates a random access procedure provides Node B with enough information to reliably accept variable cell sizes and efficiently prioritize resource requests. Must. Also, due to its potential asynchronous nature, random access signals must be designed to minimize interference with other UL orthogonal communications. Thus, a more efficient random access method is needed.

  One exemplary embodiment for more efficient random access is provided by an apparatus for transmitting a random access signal, including a CAZAC root sequence selector coupled to a CAZAC root sequence generator. . Here, the CAZAC root sequence generator generates at least one CAZAC root sequence, and the CAZAC root sequence selector spontaneously selects a preamble root sequence from at least two CAZAC root sequences. .

  Another exemplary embodiment is a method for accessing a wireless network that includes transmitting a signal that includes one CAZAC sequence that is voluntarily selected from a plurality of CAZAC sequences.

  Yet another exemplary embodiment of the present disclosure is a method for allocating uplink resources, which includes at least one CAZAC sequence selected from a plurality of CAZAC sequences and a wideband pilot signal , Analyzing the signal to estimate a frequency response of an uplink transmission channel, and allocating uplink resources based on the estimation of the frequency response.

In the detailed description that follows, reference will be made to the accompanying drawings.
The drawings illustrate exemplary embodiments and are described in detail below. However, the description and accompanying drawings are not intended to limit the claimed disclosure to those exemplary embodiments, but on the contrary, all modifications that fall within the spirit and scope of the appended claims, It is intended to disclose and protect equivalents and alternatives.

1 illustrates an example telecommunications network. FIG. FIG. 3 illustrates an example uplink time / frequency assignment. FIG. 3 illustrates exemplary 1 and 2 subframe random access signals. 1 shows a first exemplary embodiment of a random access signal transmitter. FIG. FIG. 4 shows a second exemplary embodiment of a random access signal transmitter. FIG. 4 shows a third exemplary embodiment of a random access signal transmitter. FIG. 3 illustrates an example asynchronous random access signal receiver. FIG. 4 is a flow diagram of an exemplary random access preamble signal length adjustment and transmission method. FIG. 6 is a flow diagram of an alternative exemplary random access preamble signal length adjustment and transmission method. FIG. 3 is a signal flow diagram of a conventional exemplary random access procedure. FIG. 5 is a signal flow diagram of an alternative conventional exemplary random access procedure. FIG. 5 is a signal flow diagram of an exemplary hybrid random access procedure. FIG. 4 is a flow diagram of an exemplary random access, collision, and handling method. The figure which shows the orthogonality principle employ | adopted as the orthogonal frequency division multiplexing system. FIG. 5 shows a mismatch between a random access preamble signal and a schedule data OFDM symbol. FIG. 6 illustrates alternative exemplary 1 and 2 subframe random access signals.

Disclosed herein are various systems and methods for employing a random access channel in a telecommunications system. The disclosed apparatus and method includes:
A device for transmitting and receiving random access signals.
A method for improving uplink resource allocation utilizing a random access preamble signal or a wideband pilot signal in a random access signal.
A method of encoding information in a random access signal by selecting a random access preamble signal or frequency band.
A method of allocating uplink resources using a random access preamble signal or information encoded in a frequency band.
A method for enabling high-speed load balancing using a random access preamble signal or information encoded in a frequency band.
A method of extending the length of a random access preamble signal to adapt the random access signal to a variable cell size, noise, interference state, etc.
A method for optimizing the number of recognizable random access attempts for a given time-frequency radio resource.
A method to minimize interference between random access and pre-scheduled access.
A method of adapting a prime-length random access preamble signal to be used for a random access signal.
Random access signal collision recovery method.

  Embodiments of the present disclosure are generally directed to wireless telecommunications systems and can be applied to the generation of random access transmissions. Random access transmission means transmitting at least one signal from a plurality of predefined signals by the mobile terminal. The plurality of predefined signals are specified by a random access structure. A mobile terminal, also called a user terminal (“UE”), is typically a fixed or portable wireless device, a cellular phone, a personal digital assistant, a wireless modem card, and so on. Random access transmissions are also referred to as ranging transmissions or other similar terms.

  User terminals are either synchronous uplink (“UL”) or asynchronous UL. If the UE UL is not time synchronized or has lost time synchronization, the UE can perform an asynchronous random access requesting allocation of uplink resources. In addition, the UE can perform asynchronous random access to register itself with the access point or for several other reasons. There are many users capable of random access transmission, and the scope of the present disclosure is not limited. For example, asynchronous random access adjusts the UE's transmission timing, allocating resources for subsequent uplink transmissions of the UE as needed, estimated by the access point ("Node B") Allow to do. Resource requests from asynchronous UL UEs occur for a variety of reasons. For example, new network access, data ready to be transmitted, handover procedure, etc. Node B is generally a fixed station and is referred to as a base transceiver system (BTS), access point, base station, or various other names.

  FIG. 1 illustrates an exemplary wireless telecommunications network 100. An exemplary telecommunications network includes base stations 101, 102, and 103, but in operation, the telecommunications network necessarily includes many other base stations. Each base station 101, 102 and 103 operates on a corresponding coverage area 104, 105 and 106. The coverage area of each base station is further divided into cells. In the illustrated network, the coverage area of each base station is divided into three cells. A handset or other UE 109 is shown in cell A 108, which is included in the coverage area 104 of the base station 101. The base station 101 performs transmission / reception with the UE 109. When the UE 109 leaves the cell A 108 and moves to the cell B 107, the UE 109 is handed over to the base station 102. Since UE 109 is synchronized with base station 101, UE 109 can employ asynchronous random access to initiate a handover to base station 102.

  Asynchronous UE 109 also employs asynchronous random access to request uplink 111 time or frequency or code resource allocation. If the UE 109 has data prepared for transmission, such as traffic data, measurement report, tracking area update, etc., the UE 109 can transmit a random access signal on the uplink 111. The random access signal notifies the base station 101 that the UE 109 is requesting uplink resources to transmit UE data. The base station 101 sends a message including resource parameters allocated for the uplink transmission of the UE 109 to the UE 109 via the downlink 110, with possible timing error correction. Reply by. After receiving the resource allocation and possible timing, further messages are transmitted on the downlink 110 by the base station 101. The UE 109 adjusts its transmission timing (if possible) and transmits data on the uplink 111 using the allocated resources during the indicated time interval.

  FIG. 2 shows an exemplary uplink transmission frame 202 and the allocation of frames for the schedule channel and random access channel. The exemplary uplink transmission frame 202 includes a plurality of transmission subframes. Subframe 203 is reserved for scheduled UE uplink transmission. Between the schedule subframe 203, the time and frequency resources allocated to the random access channel 201 are scattered and inserted. In FIG. 2, a single subframe supports two random access channels. The illustrated number and spacing of random access channels is for convenience only. In particular transmission frame embodiments, more or fewer resources may be allocated to the random access channel. Inclusion of multiple random access channels allows multiple UEs to transmit random access bursts simultaneously without collision. However, since each UE independently selects the random access channel on which it transmits, collisions may occur between the UE's random access signals. Such a collision needs to be resolved.

  FIG. 3 shows one embodiment of a random access signal. The random access signal 301 occupies one subframe 308, while the random access signal 311 occupies two subframes. The illustrated embodiment of one subframe random access signal 301 prevents interference between the random access preamble signal 304 and any transmission on the random access preamble signal frequency band in the previous subframe. For this reason, an interval 302 is included before transmission of the random access preamble signal 304. The details of the interval 302 are not related to the novelty of the present disclosure, but may be adopted as a cyclic prefix (“CP”) attached at the start of the preamble so as to realize a simplified frequency domain receiver. Or you don't have to. A random access preamble signal 304 follows interval 302. The random access preamble signal 304 is designed to maximize the total number of resource opportunities while maximizing the preamble detection probability by the Node B and minimizing the false preamble detection probability by the Node B.

  Embodiments of the present disclosure generate a random access preamble signal using a constant amplitude autocorrelation zero (“CAZAC”) sequence. The CAZAC sequence is a complex value sequence and has the following two properties. 1) constant amplitude (CA), 2) zero cyclic autocorrelation (ZAC). Well-known (but not limited) examples of CAZAC sequences include Chu sequences, Frank-Zadoff sequences, Zadoff-Chu sequences (ZC) and generalized A chirp-like (GCL) sequence is included.

  As is well known in the art, the Zadoff-Chu (“ZC”) sequence defined as follows is a representative example of a CAZAC sequence.

For odd N a _M (k) = exp [j2π (M / N) [k (k + 1) / 2 + qk]]
A _M (k) = exp for even ^{N [j2π (M / N)} [k 2/2 + qk]]

In the above equation, “M” and “N” are relatively prime, and “q” is an arbitrary fixed integer. “N” is the length of the sequence, “k” is the index of the sequence element, and “M” is the index of the root ZC sequence. By making “N” a prime number, the set of non-orthogonal root ZC sequences having optimal cross-correlation can be maximized. Thus, when “N” is a prime number, there are “(N−1)” possible choices for “M”, and each selection results in one individual root ZC CAZAC sequence. In this disclosure, the terms Zadoff-Chu, ZC and ZC CAZAC are used interchangeably. The term CAZAC means any CAZAC sequence, ZC or others.

  In the main embodiment of the present disclosure, the random access preamble signal 304 (or 314) is constructed from a CAZAC sequence, such as a ZC sequence. Additional modifications can be made to the chosen CAZAC sequence using any of the following operations: multiplication by complex constants, DFT, IDFT, FFT, IFFT, cyclic shift, zero Padding, sequence block repetition, sequence truncation, sequence rotation-extension and others. Thus, in the main embodiment of the present disclosure, the UE applies a combination of the above modifications to the selected CAZAC sequence, if possible, by selecting the CAZAC sequence, and modulates the modified sequence, A random access preamble signal (304 or 314) is constructed by transmitting the resulting random access signal by broadcast.

  In an actual system, it is necessary to specify or predefine a set of allowed random access preamble signals. In this way, the UE may spontaneously select (or be assigned) at least one random access preamble signal (304 or 314) from a predefined set of random access preamble signals. To do. Subsequently, the UE transmits the selected signal by broadcasting. Node B can search in a finite predefined set of random access signals and thus detect the occurrence of random access transmissions by the UE.

  One way to predefine a set of random access preamble signals is to allow a selection of modifications to one fixed root CAZAC sequence, such as a ZC CAZAC sequence. For example, in one embodiment of the present disclosure, an individual random access preamble signal is constructed by applying an individual cyclic shift when performing root CAZAC sequence modifications. That is, in this embodiment of the present disclosure, the UE spontaneously selects a random preamble access signal by selecting one value for the cyclic shift. The chosen value of the cyclic shift is applied during the root CAZAC sequence modification process. The sequence [c (0) c (1) c (2). . . c (L−1)], the corresponding cyclic shifted sequence is [c (n) c (n + 1) c (n + 2). . . c (L-1) c (0) c (1). . . c (n-1)]. Here, “n” is a cyclic shift value. Thus, in this embodiment, the set of possible cyclic shifts defines the set of allowed random access preamble signals.

  An alternative way of predefining the set of random access preamble signals is to allow selection of an applicable root CAZAC sequence such as a ZC sequence. For example, in this embodiment of the present disclosure, the individual random access preamble signal is constructed by applying a predefined common modification to the individual root CAZAC sequence. Therefore, the UE voluntarily selects the random access preamble signal by selecting one dedicated root CAZAC sequence. The UE then makes modifications to generate a random access preamble signal. Thus, in this alternative embodiment of the present disclosure, the set of allowed root CAZAC sequences defines the set of allowed random access preamble signals, again.

  In the general embodiment of the present disclosure, the set of allowed random access preamble signals is defined by two other sets. 1) Set of allowed root CAZAC sequences, 2) Set of allowed modifications to one given root CAZAC sequence. For example, in a general embodiment of the present disclosure, a random access preamble signal is constructed by first selecting a root ZC CAZAC sequence and then selecting a cyclic shift value. The selection is made voluntarily by the UE, and the UE applies the chosen value of the cyclic shift during the modification process of the chosen root ZC CAZAC sequence.

  FIG. 4 is a block diagram illustrating an apparatus according to one embodiment of the present disclosure. The apparatus 400 includes a ZC root sequence selector 401, a cyclic shift selector 402, a repeat selector 403, a ZC root sequence generator 404, a DFT in cyclic shifters 405 and 406, and other in the tone maps 407 and 411. Elements of the device, including signal or zero padding, IDFT in 408, repeater in 409, CP addition in optional repeat samples 412, 410 and random access signal in 413 are fixed processor or programmable processor Realized as a component. In some embodiments, the IDFT block in 408 is implemented using an inverse fast Fourier transform (IFFT), and the DFT block in 406 is implemented using a fast Fourier transform (FFT). Apparatus 400 is used to select and perform random access preamble signaling as follows. The UE performs selection of the ZC CAZAC root sequence using the ZC root sequence selector 401 and selection of the cyclic shift value using the cyclic shift selector 402. The UE then generates a ZC sequence using the ZC root sequence selector 404. Next, if necessary, the UE performs a selected ZC sequence cyclic shift using the cyclic shifter 405. The UE performs DFT (Discrete Fourier Transform) of the ZC sequence cyclically shifted by the DFT 406. The result of the DFT operation is mapped to a specified set of tones (subcarriers) using tone map 407. Additional signals or zero padding 411 may or may not be present. The UE then performs IDFT of the mapped signal using IDFT 408. The IDFT size at 408 may optionally be larger than the 406 DFT size. Block repetition of the IDFTed signal is optional and is performed using 409. Note that the repeated signal 412 represents an optional repeated sample. This repetition is applicable when the preamble transmission occupies more than one subframe. 410 can be used to add an optional cyclic prefix (CP) to reach the random access signal 413. The random access signal 413 is transmitted by broadcasting.

  FIG. 5 is a block diagram illustrating an apparatus according to an alternative embodiment of the present disclosure. The apparatus 500 includes a ZC route sequence selector 501, a cyclic shift selector 502, a repeat selector 503, a ZC route sequence generator 504, a DFT in cyclic shifters 505, 506, and other in tone maps 507, 511. Signal or zero padding, IDFT in 508, repeater in 509, optional repeated samples 512, CP addition in 510 and random access signal in 513. The elements of the device are implemented as components in a fixed processor or programmable processor. In some embodiments, the IDFT block in 508 is implemented using an inverse fast Fourier transform (IFFT), and the DFT block in 506 is implemented using a fast Fourier transform (FFT). Apparatus 500 is used to select and perform random access preamble signaling as follows. The UE performs ZC CAZAC root sequence selection using the ZC root sequence selector 501 and cyclic shift value selection using the cyclic shift selector 502. The UE then generates a ZC sequence using the ZC root sequence generator 504. The chosen ZC sequence is transformed using 506 DFT. The result of the DFT operation is then mapped to a specified set of tones (subcarriers) using tone map 507. Additional signals or zero padding 511 may or may not be present. The UE then uses 508 to perform IDFT of the mapped signal. Using cyclic shifter 505, the selected value of the cyclic shift is applied to the signal that has been subjected to IDFT. The value of the cyclic shift is obtained from the cyclic shift selector 502. Block iteration of the cyclically shifted IDFT signal is optional and is performed using the repeater 509. Note that 512 represents an optional repeated sample. This repetition applies when the preamble transmission occupies more than one subframe. 510 can then be used to add an optional cyclic prefix (CP) to reach the random access signal 513. The random access signal 513 is transmitted by broadcasting.

  FIG. 6 is a block diagram illustrating an apparatus according to the third embodiment of the present disclosure. Device 600 includes ZC root sequence selector 601, circular shift selector 602, repeat selector 603, ZC root sequence generator 604, circular shifter 605, other signals in signal map 607, 611 or zero padding, Include IDFT in 608, repeater in 609, optional repeated samples 612, CP addition in 610 and random access signal in 613. The elements of the device are implemented as components in a fixed processor or programmable processor. In some embodiments, the IDFT block in 608 is implemented using an inverse fast Fourier transform (IFFT). Apparatus 600 is used to select and perform random access preamble signaling as follows. The UE performs ZC CAZAC root sequence selection using the ZC root sequence selector 601 and cyclic shift value selection using the cyclic shift selector 602. The UE then generates a ZC sequence using the ZC root sequence generator 604. The chosen ZC sequence is mapped to a specified set of tones (subcarriers) using tone map 607. Additional signals or zero padding 611 may or may not be present. The UE then uses 608 to perform IDFT of the mapped signal. Using the cyclic shifter 605, the selected value of the cyclic shift is applied to the signal subjected to the IDFT. The value of the cyclic shift is obtained from the cyclic shift selector 602. Block iteration of the cyclically shifted IDFT signal is optional and is performed using 609. Note that 612 represents an optional repeated sample. This repetition applies when the preamble transmission occupies more than one subframe. 610 can then be used to add an optional cyclic prefix (CP) to reach random access signal 613. The random access signal 613 is transmitted by broadcasting.

  In various embodiments of the present disclosure, the set of allowable cyclic shifts can be sized according to the physical constraints of the cell, including the maximum round trip delay of the cell plus the channel delay spread. For example, a single root ZCCAZAC sequence is cyclically shifted by any integer multiple of the maximum round trip delay of the cell plus the delay spread, thereby generating a predefined set of random access preamble signals. The maximum round trip delay plus the channel delay spread needs to be converted to a sequence sampling unit. That is, if the maximum round trip plus the channel delay spread is given as “x”, the size of the possible selection of cyclic shift values is {0, x, 2x,. . . , (U−1) x} can be determined as n. Here, ux cannot exceed the length of the cyclically shifted sequence.

  Round trip delay is a function of cell size. Here, the cell size is defined as the maximum distance d that the UE can interact with the base station of the cell and can be approximated using the formula t = 6.67d. Here, t and d are represented by μs and km, respectively. Round trip delay is the earlier delay of the radio path. A typical faster path is a straight path, defined as a direct (straight) radio path between the UE and the base station. When the UE is surrounded by a reflector, the radio waves it radiates are reflected by those obstacles, creating multiple longer flight radio paths. Thus, multiple time-delayed copies of the UE transmission arrive at the base station. The time span in which these copies are delayed is called “delay spread”, for example, in some cases 5 μs is considered a conservative value.

  Set of cyclic shifts {0, x, 2x,. . . , (U−1) x} generates an additional root CAZAC sequence (eg, M = 2) for random access preamble signal generation if the number of individual random access preamble signals generated is insufficient. And for M = 3). In this situation, it becomes clear that the choice of prime number N is advantageous. That is, the set that can be selected for M by the prime number N is {1, 2,. . . , (N−1)}. Thus, in one embodiment of the present disclosure, the individual random access preamble signal is specified by a set of possible choices for cyclic shift values and a set of choices allowed for M. In addition to providing auxiliary cell-internal sequences, these additional root ZC CAZAC sequences provide good cell-to-cell interference mitigation when used in neighboring cells. Thus, in the design of cellular systems, scenarios where neighboring cells use the same root sequence must be avoided. This can be achieved through several possible techniques. These include, but are not limited to, cellular system planning, sequence hopping, or combinations thereof.

  The set of allowed random access preamble signals is signaled to the UE prior to random access transmission. This can be achieved in a number of different ways, including how to hardwire this information in the UE. However, the preferred method is to allow the Node B to broadcast the information so that the UE can guess the set of allowed random access preamble signals. For example, Node B can broadcast: 1) Which root CAZAC sequence is allowed, and 2) Which value of “cyclic shift” is allowed. The UE reads the broadcast information, infers an allowed set of random access preamble signals, selects at least one signal from the set, and performs random access transmission. The random access preamble signal will eventually result in the selection of the root ZC CAZAC sequence, the selection of the cyclic shift value, and possibly the frequency range (in the case where multiple ranges are configured per random access time slot) Please be careful. In certain cases, additional broadcast information is added, such as whether the UE needs to perform signal repetition. Overall, this approach is preferred in that it allows optimization of the cellular network based on physical information such as cell size, based on the broadcast of additional information. Thus, any given UE is flexible enough to use for any type of cell, and system optimization is performed by cell design.

  A sequence resulting from a cyclic shift of only one CAZAC root sequence (ZC or others) has a cyclic shift value greater than the maximum temporal uncertainty of the received signal, including delay spread and spill over Are orthogonal to each other. In other words, the cyclic shift creates a zero-correlation zone between the individual random access preamble signals. That is, a cyclically shifted sequence can be observed without interference from sequences generated using different cyclic shifts. Sequences obtained from cyclic shifts of different Zadoff-Chu (ZC) sequences are not orthogonal, but have optimal cross-correlation as long as the sequence length is a prime number. Therefore, orthogonal sequences are preferred over non-orthogonal sequences in various embodiments. For this reason, an additional Zadoff-Chu (ZC) root sequence is used if the required number of sequences cannot be generated due to the cyclic shift of a single root sequence. As a result, the size of the cyclic shift is an important concern in random access sequence design. As mentioned above, the cyclic shift value is dimensioned to allow for the largest temporal uncertainty in random access preamble reception. This time uncertainty reflects the sum of Node B-UE-Node B signal propagation delay (round trip time) and delay spread. Thus, the cyclic shift sizing ensures that individual random access signals generated from a single root CAZAC sequence are received in a zero cross-correlation zone. It can be assumed that the delay spread is constant, but the signal round trip time depends on the cell size. That is, as the cell grows, the cyclic shift used to generate the orthogonal sequence grows, and accordingly the Zadoff-Chu (ZC) root sequence used to provide the required number of sequences. The number of increases.

  Table 1 shows an example design of a random access preamble sequence corresponding to different cell sizes. Table 1 shows how the number of root ZC CAZAC sequences increases from 1 to 8 as the cell size increases from 0.8 km (cell scenario 1) to 14 km (cell scenario 4). Show. Table 1 was derived using the following parameters: maximum delay spread of 5 microseconds, root ZC CAZAC sequence length of 863 samples, preamble sampling rate of 1.07875 MHz and spill over guard guard The interval is 2 samples. As the cell size decreases, the expected inter-cell interference and load (user density) increases, so small cells need to be better protected from simultaneous preamble interference than larger cells. Thus, the relationship between cell size and the required Zadoff-Chu (ZC) route sequence allows system optimization, and Node B is used independently in each cell. The basic cyclic shift must be configured as follows. Accordingly, the set of cyclic shift values to be used is configured to be an integer multiple of the basic cyclic shift value. As shown in Table 1, the system can be optimized by configuring the basic cyclic shift value or by configuring the number of different root Zadoff-Chu (ZC) sequences to use in the cell. This configurability advantageously provides a fixed number of individual random access preamble signals regardless of cell size, thereby simplifying the specification of the medium access control (MAC) procedure.

  FIG. 7 shows an embodiment of a random access signal receiver. The receiver advantageously takes advantage of the time and frequency domain transform components used to map and demapping data blocks in the uplink subframe. A received random access signal 701 that includes a cyclic prefix and a random access preamble signal is input to a cyclic prefix removal component 702, which removes the cyclic prefix from the random access signal and generates a signal 703. The frequency domain transform component DFT 704 leads to a cyclic prefix removal component 702. The frequency domain conversion component 704 converts the signal 703 into a subcarrier map frequency tone 705. The subcarrier demapping component 706 leads to the frequency domain transform component 704. Subcarrier demapping component 706 demaps subcarrier mapped frequency tone 705 to produce useful frequency tone 707. Product component 711 leads to both subcarrier demapping component 707 and frequency domain transform component 709. A frequency domain transform component (DFT) 709 transforms a preamble root sequence 710 such as a prime length Zadoff-Chu sequence into a corresponding set of pilot frequency tones 708. A complex conjugate of pilot frequency tone 708 is performed using 721 to generate sample 720. Product component 711 calculates tones by a tone complex multiplication of received frequency tone 707 and sample 720 to generate a set of frequency tones 712. A time domain conversion component (IDFT) 713 leads to a product component 711. The time domain transform component 713 converts the multiplied frequency tone 712 into a corresponding time signal 714. Correlated time signal 714 includes a concatenated power delay profile of cyclic shift replicas of preamble root sequence 710. The energy detection block 715 leads to the time domain conversion block 713. The energy detection block 715 identifies the received preamble sequence by detecting the time of peak correlation between the received random access signal 701 and the preamble root sequence 710. Note that the frequency domain transform component 709 is required when using the transmitter shown in FIG. 4 or FIG. When the transmitter of FIG. 6 is used, the frequency domain transform component 709 is omitted.

As already mentioned, prime length preamble sequences are recommended for use with uplink transmitter systems. The prime length preamble sequence is constructed as follows: Preamble length T _p is optimized to optimize cell coverage (cell size, noise and interference conditions), and uplink data block length. Is selected to be an integer multiple of. N _pi = T _p × R _si samples are selected as the reference length. Where R _si is the allocated random access signal bandwidth, which is not used for data transmission. Next, a preamble sequence having a sequence length corresponding to the largest prime number N _p smaller than the reference length N _pi is generated. Thus, since the preamble length remains T _p , the preamble sampling rate is R _si × N _p / N _pi . N _pi subcarriers are assigned to the random access channel, and the preamble is shortened to the nearest lower-order prime sample (N _p ), resulting in unused subcarriers, which are zero and And distributed outside the preamble subcarriers to separate the preamble from the surrounding frequency bands.

FIG. 8 shows a flow diagram of an exemplary method for adapting a prime length sequence for use with an uplink transmitter. In 802, the preamble length _{T p} is chosen. T _p is an integer multiple of the uplink subframe data block length. At 804, a reference length is derived. This reference length is N _pi samples. Here, N _pi = T _p × R _si , where R _si is the random access signal bandwidth. In 806, the reference length derived in 804, recently been reduced to samples N _p of contact of the lower prime preamble sequence length is derived. In 807, a sequence of _{N p} length is generated. At 808, N _p time samples are converted to N _p frequency tones. N _p frequency tones are mapped 810 to assigned random access channel subcarriers. Since N _pi subcarriers are assigned to the random access channel and the preamble sequence length is reduced to N _p samples, the frequency tones mapped to the subcarriers are only N _p , and N _pi −N _p Subcarriers remain unused. At 812, unused subcarriers are zeroed out and distributed around the preamble subcarriers to provide separation from adjacent frequency bands. These unused subcarriers can be reused for three-dimensional size reduction through either cyclic expansion or tone reservation.

  FIG. 9 shows a flow diagram of an alternative method of generating a prime length sequence for use with an uplink transmitter. Since the preamble sequence is deterministic, the prime length preamble sequence can be predefined and stored for later use. At 902, once configured by the Node B, a prime length preamble sequence is generated and converted to frequency domain preamble samples. At 904, the frequency domain preamble samples can be stored in a storage device and retrieved as needed. At 906, random access signal transmission is initiated and a preamble length is selected. The chosen length is an integer multiple of the uplink subcarrier data block length and is chosen to meet the coverage requirements of the system. At 908, a stored preamble sequence is selected. The chosen sequence is preferably a sequence having a prime number of samples that are immediately below the number of samples calculated from the length chosen at 906 and having a random access signal bandwidth. At 910, preamble frequency samples are read from the storage device and mapped to subcarriers assigned to the random access channel. Since there are more subcarriers allocated to the random access channel than there are preamble frequency samples, unused subcarriers are zeroed out and distributed around the preamble subcarriers from adjacent frequency bands. Provide separation. This alternative implementation allows the frequency domain transform component 402 to be omitted from the random access preamble transmitter. Preamble samples are frequency domain transformed once before they are stored, so the transformation process is irrelevant to the random access preamble transmitter latency requirements and is implemented in a simpler and less expensive manner it can. It should also be noted that the frequency domain transform component 406 can be omitted entirely if the preamble root sequence is constructed with a frequency representation directly by the Node B. However, since the preamble sequence is defined to be a cyclically shifted Zadoff-Chu sequence, a cyclic shift is included. The cyclic shift is performed at the system sampling rate prior to cyclic prefix insertion 410.

  FIG. 14 illustrates the principle of orthogonal multiplexing in an orthogonal frequency division multiplexing (“OFDM”) system. Each tone carries a modulated symbol according to a frequency superposition time limited orthogonal structure. Since the frequency tones overlap each other, in the middle of one tone, the spectral envelope of the surrounding tone is zero. This principle allows different transmissions to be multiplexed orthogonally within the same system bandwidth. However, this is correct only when the subcarrier spacing δf is kept constant. δf is proportional to the reciprocal of the OFDM symbol length T used for generating frequency tones by DFT. Since the preamble OFDM symbol is longer than the data OFDM symbol, the subcarrier interval of the preamble OFDM symbol is shorter than the subcarrier interval of the data OFDM symbol. Furthermore, since the OFDM symbols of the data and preamble are neither aligned nor have the same length (FIG. 15), strict orthogonality cannot be realized. However, the next design rule is aimed at minimizing simultaneous interference between preamble and data OFDM symbols. Initially, fixing the preamble OFDM symbol length to an integer multiple of the data symbol length provides some interoperability between the preamble and data subcarriers, thereby reducing interference between these subcarriers. Second, the preamble sampling frequency should be an integer multiple of the data symbol subcarrier spacing.

  In an OFDM system, transmissions of different UEs are dynamically assigned to different non-overlapping frequency bands. This allocation is generally based on a minimum frequency granularity (granularity) called a resource block (RB). In order to facilitate frequency multiplexing of the random access preamble and data transmission, the preamble is preferably assigned an integer value of the resource block.

  In addition to the detection process, random access preamble signal 304 allows base station 101 to analyze the frequency response of uplink 111 over a range of frequencies in the preamble bandwidth. Evaluation of the frequency response of the uplink 111 is that the base station 101 adjusts the narrow band uplink 111 resource allocated to the UE 109 within the preamble bandwidth to match the frequency response of the uplink 111. Resulting in more efficient use of uplink resources.

  FIG. 16 shows that the ratio of the bandwidth of the random access preamble signal to the first post preamble uplink transmission is too small and the channel is consulted using only the random access preamble signal. Fig. 4 illustrates another embodiment of a random access signal designed to address situations where it does not benefit properly. Both one subframe random access signal 1601 and two subframe random access signal 1602 are shown. By adding a wideband pilot signal 1610 to the random access signal 1601, the base station 101 can determine the frequency response of the uplink 111 over a wider frequency range than would be possible with a random access preamble signal alone. Can be analyzed.

  In the illustrated embodiment, a cyclic prefix 1608 follows the random access preamble signal 1604. Cyclic prefix 1608 includes a guard interval designed to eliminate interference between random access preamble signal 1604 and wideband pilot signal 1610.

  A guard interval 1612 follows the wideband pilot signal 1610 and between any transmissions in subsequent subframes on the same transmission frequency used by the wideband pilot signal 1610 and the wideband pilot signal 1610. To prevent interference.

  The random access signal 1621 occupies two subframes 1634. The random access signal 1621 is structurally similar to the random access signal 1601, but the random access preamble signal 1624 is extended to occupy most of the two subframes. Such an extension is realized either by repeating the random access preamble signal 1604 of one subframe or by extending the CAZAC sequence. Guard interval 1622 precedes random access preamble signal 1624 and cyclic prefix 1628. A wideband pilot signal 1630 and a guard interval 1632 follow the random access preamble signal 1624 to complete a two subframe random access signal 1621.

  Referring again to FIG. 3, the guard interval 306 follows the random access preamble signal 304, and the random access preamble in subsequent subframes on the same transmission frequency that the random access preamble signal 304 uses. Prevent interference between signal 304 and any transmissions.

  In FIG. 3, a two-subframe random access signal 311 begins at a guard interval 312. This includes a cyclic prefix and prevents intersymbol interference between the subsequent random access preamble signal 314 and any transmission of the previous subframe. The random access preamble signal 314 is extended to the second subframe. Such extension can be achieved by either concatenating multiple copies of the random access preamble signal 304 of one subframe or by generating the random access preamble signal 314 as an extended CAZAC sequence. This is achieved so as to keep the number of orthogonal CAZAC sequences obtained by cyclically shifting CAZAC sequences substantially constant. Although two subframes of random access signals are shown, random access signals containing any number of subframes needed to accommodate special cell sizes and noise and interference conditions can be constructed as well. It is. In the embodiment shown in FIG. 3, a guard interval 318 follows the random access preamble signal 314 to complete a two subframe random access signal 311.

  In some embodiments, it may be desirable to transfer some information as part of the random access procedure to facilitate the base station schedule for subsequent UE transmissions. Random access motivation, UE identifier, required capacity and downlink radio link quality indicators (eg, channel quality indicator “DL CQI” or path loss) are included for the base station when included in the random access procedure. An example of potentially valuable information. 10 and 11 show two conventional schemes for transferring data during random access. In FIG. 10, the UE 1001 transmits a random access signal 1003. Random access signal 1003 is extended to include information useful to Node B 1002. Node B 1002 responds with timing information 1004 for adjusting the uplink timing of UE 1001 and an uplink resource allocation 1005 that UE 1001 uses for subsequent uplink data transmission 1006.

  In FIG. 11, the UE 1101 transmits a random access signal 1103 without additional information. Node B 1102 responds with the uplink resource allocation 1104 and timing information used by subsequent schedule request 1105. UE 1101 sends a schedule request 1105 using the assigned uplink resource, and Node B 1102 responds by sending an uplink resource assignment 1106. UE 1101 uses the assigned uplink resource for subsequent uplink data transmission 1107.

  The procedure of FIG. 10 shows a shorter waiting time than the procedure of FIG. However, in order to achieve an acceptable error rate, the information message contained in the burst 1003 must be several times longer than the preamble. Thus, the procedure of FIG. 10 results in greater overhead than the procedure of FIG. Finally, if a more efficient schedule channel is desired compared to a contention channel, the procedure of FIG. 11 is preferred.

FIG. 12 shows a novel embodiment of a random access procedure where UE 1201 transmits a random access signal that implicitly includes information related to Node B 1201 policy decisions. The information 1201 is not explicitly conveyed as in the procedure of FIG. 10, but is encoded by, for example, selection of a preamble sequence and a transmission band. If, for example, UE 1201 encodes a 3-bit random access motive, a 2-bit DL CQI and one random bit of the random access signal, this information can be stored in any 2 bits of the random access preamble signal. Encoded into ⁶ unique combinations. By assigning multiple frequency bands 201 to random access, additional combinations can be provided. When Node B 1202 receives a random access signal 1203, it employs encoded information, for example, to determine a response to a resource request. The determined response is based on a predefined uplink assignment based on downlink channel quality, resource request urgency, random access motivation, or other relevant criteria. Node B 1202 responds to random access signal 1203 with timing information and scheduling request resource assignment 1204 if appropriate. UE 1201 transmits scheduling request 1205 using the transmission resource allocated in message 1204. Upon receiving the scheduling request 1205, the Node B 1202 transmits an uplink resource allocation 1206, and the UE 1201 performs subsequent data transmission via the allocated resource. In another embodiment, the procedure of FIG. 10 is employed, but encoded by selection of a random access signal parameter, such as a random access preamble signal or frequency band, as previously disclosed in this paragraph. With information, thereby avoiding the inefficiency of the procedure of FIG. 10 and taking advantage of the reduced latency of the procedure of FIG.

  Encoding random access motives in the random access signal allows selective access restrictions to be implemented based on the random access motives. For example, in a heavily loaded cell, Node B accepts UE random access attempts related to handovers or emergencies, but rejects random access attempts for initial access. This example shows a hard limitation that eliminates new users based on cell load. However, soft restrictions that allow new users to be accepted based on link quality are also possible. Allowing selective access restrictions based on random access motives encoded in random access signals enables fast and efficient load balancing in the physical layer and is implemented in higher layers Reduce the waiting time associated with a given load balance.

  In order to support load balancing according to the present disclosure, the random access procedure supports the following features: 1) The random access signal includes random access motivation. 2) Node B is adapted to reject UE requests due to unacknowledged (NACK) in random access response.

As a further refinement of the disclosed implicit information encoding method, ²⁶ combinations (signatures) of random access preamble signals used to encode information may have similar response prioritization or latency. It is further subdivided into groups of signatures that are useful for applications that have requirements. In one embodiment, the 64 available signatures are divided into six groups (“access types”). Access types include, for example, handover type 1, high priority UE connection, handover type 2, normal priority UE connection, asynchronous recovery with uplink assignment request and pre-timing without uplink assignment request・ Maintenance. Each access type represents a different access priority or urgency and therefore represents a corresponding latency requirement. Each access type employs a different number of signatures, and more signatures are assigned to access types that require low latency. The number of signatures assigned to each access type is dynamically configured within each cell to optimize access type signature diversity, eg, based on cell load.

  Additional information, eg, DL CQI, is encoded in the access type signature by selecting a signature subgroup to represent the information value. For example, if 16 signatures are assigned to handover type 1, these signatures are divided into 2 subgroups, each containing 8 signatures, so that each subgroup represents one state of one information bit. Is done.

  In another embodiment, the 64 available signatures have two motivation groups: emergency motivation (eg, handover, new data to send in RRC_CONNECTED state) and non-emergency motivation (eg, initial access, tracking area update). It is divided into. Fair partitioning assigns each group a number of signatures corresponding to each group's respective load. However, unfair partitioning is also used to prioritize urgent motives (more signatures) over non-urgent motives (less signatures). Furthermore, the emergency motivation is further divided into two sub-partitions to carry one bit, eg radio link quality. Node B exploits this information when assigning UL grants for the first UL transmission on the shared channel. That is, a UE with good radio link conditions and urgent motivation can send its complete random access request in one message, further accelerating the procedure.

  For random access channels, it is preferable to avoid collisions. Signature diversity is the primary means of collision avoidance. However, when collisions occur, they need to be resolved. The collision is resolved, for example, by a combination of back-off procedure and signature space randomness. As pointed out above, access types that require shorter latencies should be assigned more signatures to reduce the likelihood of collisions when signatures are chosen randomly. Further, the expected load of each access type is a consideration when assigning a signature to each access type. For example, by reducing the load, sort the list of the six access types identified above as follows: Handover Type 1, Asynchronous Recovery with Uplink Assignment Request, No Uplink Assignment Request Pre-timing maintenance, handover type 2, high priority UE connection and normal priority UE connection. Signature assignment considering both latency and load results in the following: Handover type 1-16 signature, pre-timing maintenance without uplink assignment request-16 signature, with uplink assignment request Asynchronous recovery-12 signature, high priority UE connection-8 signature, handover type 2-8 signature and normal priority UE connection-4 signature.

  If the access type is applicable to both contention-based and non-contention-based access, the accompanying signature is partly random and partly non-contentionable Assigned to use.

  Since conflict resolution through the back-off procedure increases latency, the back-off procedure should be employed in combination with random signature selection only when necessary. FIG. 13 is a flow diagram of an exemplary collision resolution method that employs both back-off and signature space randomness. At 1302, an unscheduled transmission procedure is initiated by zeroing a counter that holds the number of detected collisions. At 1304, one signature is randomly selected from the pool of available signatures. At 1306, the next random access time slot is identified, and at 1308, a random access signal is transmitted. If Node B detects a collision at 1310 and sends a NACK to the UE, or because of the collision, Node B cannot detect a random access signal and there is no response detected by the UE at 1312 The collision counter is incremented at 1318 and if the number of collisions recorded at 1320 is less than the predefined maximum number of collisions, transmission is resumed at 1304 with random signature selection.

  If the random access signal transmitted at 1308 is not NACKed by Node B at 1310 and a response including a resource allocation is received from Node B at 1312, the UE on the source assigned its data at 1314 Send to. If a collision occurs during 1308 random access signal transmissions and Node B fails to detect the collision and transmits a single resource allocation to be used by multiple UEs, the 1314 UE transmission is: Cause a collision. If this collision is detected by the UE at 1316, the collision counter is incremented at 1318 and if the number of collisions recorded at 1320 is less than the predefined maximum number of collisions, transmitted at 1304 with random signature selection Is resumed.

If a predefined maximum number of collisions is recorded at 1320, then a back-off procedure is initiated at 1322. The predefined maximum number of collisions is different for each access type. The back-off delay is also different for each access type. In one embodiment, the back-off delay is a function of the number of previously unsuccessful attempts (Nu) so that the first attempt after back-off is a probability in the next random access time slot. (2/3) It occurs in ^Nu .

  The disclosed first embodiment of the present disclosure includes an apparatus for transmitting a random access signal including a CAZAC root sequence selector coupled to a CAZAC root sequence generator. Here, the CAZAC root sequence generator generates at least one CAZAC root sequence, and the CAZAC root sequence selector selects one preamble root sequence from the at least one CAZAC root sequence. Furthermore, the CAZAC root sequence generator is a Zadoff-Chu sequence generator. The apparatus is further connected to a CAZAC root sequence generator to modify a preamble root sequence and a sequence connected to the sequence modifier to select a preamble root sequence modification. And a correction selector. Furthermore, the sequence modifier is a cyclic shifter. The apparatus may further include a frequency transformer coupled to the sequence modifier to convert the modified preamble sequence to a frequency tone. The apparatus may further include a tone mapper coupled to the frequency transformer to map the output of the frequency transformer to the subcarrier. The apparatus may further include an inverse frequency transformer coupled to the tone mapper for converting the output of the tone mapper. The apparatus may further include a block repeater coupled to the inverse frequency transformer for replicating the output of the inverse frequency transformer and a block repeater coupled to the block repeater for selecting block replication. The apparatus may further include a cyclic prefix inserter coupled to the block repeater for adding a cyclic prefix to the output of the block repeater.

  A second embodiment of the disclosed disclosure includes an apparatus for transmitting a random access signal including a CAZAC root sequence selector connected to a CAZAC root sequence generator. Here, the CAZAC root sequence generator generates at least one CAZAC root sequence, and the CAZAC root sequence selector selects one preamble root sequence from the at least one CAZAC root sequence. The apparatus may further include a tone mapper coupled to the CAZAC route generator to map the preamble route sequence to subcarriers. The apparatus may further include an inverse frequency transformer coupled to the tone mapper for converting the output of the tone mapper. The apparatus may further include a sequence modifier coupled to the inverse frequency transformer to modify the output of the inverse frequency transformer and a sequence modification selector coupled to the sequence modifier to select the sequence modification. . Further, the sequence modifier may include a cyclic shifter. The apparatus further includes a block repeater coupled to the sequence modifier to replicate the output of the sequence modifier, and a block repeat selector coupled to the block repeater to select block replication. But you can. The apparatus may further include a cyclic prefix inserter coupled to the block repeater for adding a cyclic prefix to the output of the block repeater.

  The third embodiment of the disclosed disclosure includes a CAZAC root sequence selector connected to a CAZAC root sequence generator and includes an apparatus for transmitting a random access signal. Here, the CAZAC root sequence generator generates at least one CAZAC root sequence, and the CAZAC root sequence selector selects one preamble root sequence from the at least one CAZAC root sequence. The apparatus may further include a frequency transformer coupled to the sequence modifier to convert the modified preamble sequence to a frequency tone. The apparatus may further include a tone mapper coupled to the CAZAC route generator to map the preamble route sequence to subcarriers. The apparatus may further include an inverse frequency transformer coupled to the tone mapper for converting the output of the tone mapper. The apparatus may further include a sequence modifier coupled to the inverse frequency transformer to modify the output of the inverse frequency transformer and a sequence modification selector coupled to the sequence modifier to select the sequence modification. . Further, the sequence modifier may include a cyclic shifter. The apparatus further includes a block repeater coupled to the sequence modifier to replicate the output of the sequence modifier, and a block repeat selector coupled to the block repeater to select block replication. But you can. The apparatus may further include a cyclic prefix inserter coupled to the block repeater for adding a cyclic prefix to the output of the block repeater.

  In another aspect, one embodiment of the disclosed disclosure includes a frequency transformer connected to a complex multiplier for converting a root CAZAC sequence into pilot tones for receiving a random access signal Including devices. The apparatus may further include a subcarrier demapping component coupled to a complex multiplier for demapping the subcarrier mapped frequency tones. The apparatus may further include a frequency transformer coupled to the subcarrier demapper for converting the random access signal to subcarrier mapped frequency tones. The apparatus may further include a cyclic prefix remover coupled to the frequency transformer to remove the cyclic prefix from the random access signal. The apparatus may further include an inverse frequency transformer coupled to the complex multiplier for converting the complex multiplier output into a time signal. The apparatus may further include an energy detector coupled to the inverse frequency transformer to detect the peak correlation between the random access signal and the root CAZAC sequence.

  One method of the disclosed disclosure includes transmitting a signal and including a method of accessing a wireless network. The signal includes one CAZAC sequence selected from a plurality of CAZAC sequences. The method may further include a prime length Zadoff-Chu sequence. Furthermore, the length of the signal is determined independently for each network cell. An integer number of resource blocks are allocated for the transmission of the signal, and the length of the signal is an integer number of data symbols. The plurality of CAZAC sequences are further divided into groups including non-contention usage groups and contention usage groups. The plurality of CAZAC sequences includes a CAZAC sequence generated by modifying at least one root CAZAC sequence. Modifications applied to the at least one root CAZAC sequence include a cyclic shift. The cyclic shift applied to at least one root CAZAC sequence is an integer multiple of (maximum cell round trip delay + delay spread) for the telecommunication network cell. The method may further include determining a cyclic shift that is independently applied to at least one roux and CAZAC sequence for each telecommunication network cell. The method may further include analyzing the signal to estimate a frequency response of an uplink transmission channel and allocating uplink resources based on the estimation of the frequency response. The method may further include analyzing the random access preamble signal to estimate an uplink frequency response. The method may further include allocating uplink resources based on the estimated frequency response of the uplink. The method may further include transmitting at least one wideband pilot signal. The method may further include analyzing the wideband pilot signal to estimate an uplink frequency response. The method may further include allocating uplink resources based on the estimated uplink frequency response. Multiple CAZAC sequences represent multiple information values. The information represented by the random access preamble signal includes at least one of a downlink channel quality indicator and a random access motive. The method may further include allocating transmission resources based on the random access motive. The method may further comprise the step of load balancing telecommunications network cells with selective access constraints in accordance with the random access motivation. The method may further include the step of further dividing the plurality of CAZAC sequences into access type groups. The method may further include assigning the plurality of CAZAC sequences to an access type group according to an access type latency requirement. The method may further comprise randomly selecting a CAZAC sequence to be transmitted from a plurality of CAZAC sequences assigned to the access type. The method may further include further dividing the plurality of CAZAC sequences assigned to each access type into subgroups. Here, each subgroup represents one information value. The method may further include determining, for each telecommunication network cell, the number of CAZAC sequences per access type group and further dividing the access type group into subgroups representing information. .

  The disclosed second method of the present disclosure includes calculating a frequency domain CAZAC sequence, storing the frequency domain CAZAC sequence in a storage device, reading the frequency domain CAZAC sequence from the storage device, and randomizing the frequency domain CAZAC sequence. Mapping to subcarriers assigned to the access channel, including a method for adapting a random access preamble for uplink transmission.

  Further disclosed is a random access signal collision comprising randomly selecting one random access preamble signal from a plurality of random access preamble signals and delaying transmission of the random access signal. It is a method to solve.

  While exemplary embodiments of this disclosure have been illustrated and described, those skilled in the art can make modifications without departing from the spirit and teachings of this disclosure. The embodiments described herein are illustrative and not restrictive. Many different variations and modifications of the system and apparatus are possible within the scope of this disclosure. Accordingly, the scope of protection is not limited by the embodiments described herein, but only by the scope of the claims. The claims should encompass all equivalents of the claimed subject matter.

(Statement concerning research and development with federal government support)
Not applicable

Claims (13)

An apparatus for transmitting a random access signal,
A CAZAC root sequence selector coupled to a CAZAC root sequence generator that generates two or more constant amplitude zero autocorrelation (CAZAC) root sequences, comprising: a preamble root from one of the CAZAC root sequences; The CAZAC root sequence selector for selecting a sequence; and
A circular shifter coupled to the CAZAC root sequence generator to modify the preamble root sequence;
A sequence modification selector coupled to the cyclic shifter for selecting a preamble root sequence modification;
A frequency transformer coupled to the sequence modification selector to convert the modified prime length preamble sequence to a prime number of frequency tones;
A tone mapper coupled to the frequency transformer for mapping prime number frequency tones to non-prime frequency tones;
An inverse frequency transformer coupled to the tone mapper for converting the output of the tone mapper;
A block repeater coupled to the inverse frequency transformer to replicate the output of the inverse frequency transformer;
A block repeat selector coupled to the block repeater for selecting block duplication;
A cyclic prefix inserter coupled to the block repeater to add a cyclic prefix to the block repeater output;
Including the device. A method of accessing a wireless network comprising:
Transmitting a signal, wherein the signal is autonomously selected from a plurality of CAZAC sequences generated by applying a cyclic shift to at least one root constant amplitude zero autocorrelation (CAZAC) sequence; Contains concatenated cyclic prefixes,
An integer number of frequency resource blocks are allocated for transmission of the signal;
The method, wherein the duration of the CAZAC sequence is an integer number of data symbols to facilitate random access channel (RACH) and data multiplexing by reducing orthogonality loss. A method of accessing a wireless network comprising:
Transmitting a signal, wherein the signal is a CAZAC sequence that is autonomously selected from a plurality of CAZAC sequences generated by applying a cyclic shift to at least one root constant amplitude zero autocorrelation (CAZAC) sequence. Including
The method wherein the plurality of CAZAC sequences are subdivided into groups including a non-contention usage group and a contention usage group. A method of accessing a wireless network comprising:
Transmitting an asynchronous random access signal from a plurality of prime length Zadoff-Chu sequences generated by applying a cyclic shift to at least one root prime length Zadoff-Chu sequence. Said transmitting step comprising an autonomously selected prime length Zadoff-Chu sequence;
Determining, independently for each telecommunications network cell, a cyclic shift increment applied to at least one route prime length Zadoff-Chu sequence;
Including a method. An apparatus for transmitting a random access signal,
An apparatus for autonomously selecting the signal x (u) and the cyclic shift c from the set of candidate signals and cyclic shift values;
A Zadoff-Chu sequence generator used to generate the signal x (u);
A cyclic shifter that uses signal x (u) to generate a shifted signal y (u) = x [(u−c) mod U], where c is the selected cyclic shift and U is the signal a cyclic shifter that is the length of x (u);
An asynchronous transmitter that transmits the signal x (u) regardless of the timing of the target remote receiver;
A discrete Fourier transform (DFT) transformer coupled to a cyclic shifter to generate a frequency domain signal;
An inverse discrete Fourier transform (IDFT) transformer coupled to a DFT transformer to generate a time domain signal;
A block repeater coupled to the IDFT transformer and replicating the time domain signal;
A cyclic prefix inserter coupled to a block repeater;
Including the device. An apparatus for transmitting a random access signal,
An apparatus for autonomously selecting the signal x (u) and the cyclic shift c from the set of candidate signals and cyclic shift values;
A Zadoff-Chu sequence generator used to generate the signal x (u);
A cyclic shifter that uses said signal x (u) to generate a shifted signal y (u) = x [(u−c) mod U], where c is the selected cyclic shift, and U is A cyclic shifter that is the length of the signal x (u);
An apparatus for generating a random access OFDM symbol of period T1 that does not include a cyclic prefix period;
An apparatus for generating a non-random access OFDM symbol of period T2 that does not include a cyclic prefix period;
Including
An apparatus wherein T1 is an integer multiple of T2. A method of accessing a wireless network comprising:
Autonomously selecting a Zadoff-Chu sequence x (u) and a cyclic shift c from a set of candidate sequences and cyclic shift values;
Generating a random access signal x (u) using a Zadoff-Chu sequence generator;
Generating a cyclically shifted signal y (u) = x [(u−c) mod U], where c is the cyclic shift, U is the length of the signal x (u), and x ( u) is the Zadoff-Chu sequence;
generating a frequency domain signal by transforming y (u) with a discrete Fourier transform (DFT);
Extending the frequency domain signal by embedding zeros;
Generating a time domain signal by transforming the expanded frequency domain signal with an inverse discrete Fourier transform (IDFT);
Repeating the time domain signal;
Inserting a cyclic prefix into the repeated time domain signal;
Broadcasting an indication of the number of repetitions of the time domain signal, which is a cell specific parameter;
Including a method. A method of accessing a wireless network comprising:
Autonomously selecting a Zadoff-Chu sequence x (u) and a cyclic shift c from a set of candidate sequences and cyclic shift values;
Generating a random access signal x (u) using a Zadoff-Chu sequence generator;
Generating a cyclically shifted signal y (u) = x [(u−c) mod U], where c is a cyclic shift and U is the length of the signal x (u); ,
Frequency multiplexing a random access OFDM symbol of period T1 with a non-random access OFDM symbol of period T2;
Including
The method, wherein T1 is an integer multiple of T2. A method of accessing a wireless network comprising:
Autonomously selecting a Zadoff-Chu sequence x (u) and a cyclic shift c from a set of candidate sequences and cyclic shift values;
Generating a random access signal x (u) using a Zadoff-Chu sequence generator;
Generating a cyclically shifted signal y (u) = x [(u−c) mod U], where c is a cyclic shift and U is the length of the signal x (u); ,
Estimating the size of cells in the wireless network; and
Generating c using the estimated cell size;
broadcasting the instruction of c;
Including a method. A method of accessing a wireless network comprising:
Autonomously selecting a Zadoff-Chu sequence x (u) and a cyclic shift c from a set of candidate sequences and cyclic shift values;
Generating a random access signal x (u) using a Zadoff-Chu sequence generator;
Generating a cyclically shifted signal y (u) = x [(u−c) mod U], where c is a cyclic shift and U is the length of the signal x (u); ,
Receiving a random access signal;
Estimating the frequency response of the uplink transmission using the received random access signal;
Allocating uplink resources based on the frequency response estimate;
Including a method. An apparatus for transmitting a random access signal,
A prime length Zadoff-Chu root sequence selector coupled to a prime length Zadoff-Chu root sequence generator that generates two or more prime length Zadoff-Chu root sequences, wherein the prime length Zadoff The prime length Zadoff-Chu root sequence selector for autonomously selecting a preamble root sequence from one of the Chu root sequences;
A cyclic shifter coupled to the prime length Zadoff-Chu root sequence generator for autonomously modifying the preamble root sequence;
A sequence modification selector coupled to the cyclic shifter for selecting a preamble root sequence modification;
A signal generator coupled to the sequence modification selector to generate a signal x (u) from the modified preamble root sequence;
An asynchronous transmitter that transmits the signal x (u) regardless of the timing of the target remote receiver;
A frequency transformer coupled to the sequence modification selector to convert the modified prime length preamble sequence to a prime number of frequency tones;
A tone mapper coupled to the frequency transformer for mapping prime number frequency tones to non-prime frequency tones;
Including the device. An apparatus for transmitting a random access signal,
An apparatus for autonomously selecting the signal x (u) and the cyclic shift c from the set of candidate signals and cyclic shift values;
A Zadoff-Chu sequence generator used to generate the signal x (u);
A cyclic shifter that uses signal x (u) to generate a shifted signal y (u) = x [(u−c) mod U], where c is the selected cyclic shift and U is the signal a cyclic shifter that is the length of x (u);
An asynchronous transmitter that transmits the signal x (u) regardless of the timing of the target remote receiver;
A discrete Fourier transform (DFT) transformer coupled to a cyclic shifter to generate a frequency domain signal;
An inverse discrete Fourier transform (IDFT) transformer coupled to a DFT transformer to generate a time domain signal;
A block repeater coupled to the IDFT transformer and replicating the time domain signal;
A cyclic prefix inserter coupled to a block repeater;
A circuit for receiving an indication of the number of iterations used by the block repeater;
Including the device. A method of accessing a wireless network comprising:
Estimating the size of cells in the wireless network; and
Generating a basic cyclic shift value C using the estimated cell size;
Broadcasting the instructions of C;
Autonomously selecting a Zadoff-Chu sequence x (u) from a set of candidate cyclic shifts and a set of cyclic shifts c, which is constructed as an integer multiple of C;
Generating a random access signal x (u) using a Zadoff-Chu sequence generator;
Generating a cyclically shifted signal y (u) = x [(u−c) mod U], where c is a cyclic shift and U is the length of the signal x (u); ,
Including a method.

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