`
`'ST‘I£31703
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`0ch
`
`PROVISIONAL APPLICATION FOR PATENT COVER SHEET
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`Inventor Name
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`and either State or Forein Count
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`Jun Tan
`
`Lake Zurich, Illinois, United States
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`TITLE OF THE INVENTION (280 characters maximum
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`PREAMBLE SEQUENCING FOR RANDOM ACCESS CHANNEL IN A COMMUNICATION
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`PROVISIONAL APPLICATION COVER SHEET
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`Additional Page
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`INVENTOR S [APPLICANT S
`
`Inventor Name
`
`Residence
`Cit and either State or Forein Count
`
`Amitava Ghosh
`Raeeat Ratasuk
`Fan Wan -
`Weimin Xiao
`
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`PETITIONERS 1056-0003
`IPR2016-00758
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`

`

`PATENT APPLICATION
`
`Attorney Docket No. CE15637R
`
`TECHNICAL FIELD OF THE INVENTION
`
`[001]
`
`This invention relates generally to communications and more
`
`particularly to use of a random access channel in a communication system.
`
`BACKGROUND OF THE INVENTION
`
`PREAMBLE SEQUENCING FOR RANDOM ACCESS CHANNEL
`IN A COMMUNICATION SYSTEM
`
`resources, thereby wasting transmission resources.
`
`[002]
`
`Various communications protocols are known in the art. For example,
`
`the Third Generation Partnership Project (3GPP) has been working towards developing
`
`a number of protocols for use with a wireless communication path. The original scope
`
`of 3GPP was to produce globally applicable technical specifications and technical
`
`reports for a 3rd generation mobile system based on evolved Global System for Mobile
`
`communication (GSM) core networks and the radio access technologies that they
`
`support, such as Evolved Universal Terrestrial Radio Access (EUTRA) including both
`
`Frequency Division Duplex (FDD) and Time Division Duplex (TDD) modes. 3GPP's
`
`scope was subsequently amended to include the maintenance and development of GSM
`
`technical specifications and technical reports including evolved radio access
`
`technologies (6. g. General Packet Radio Service (GPRS) and Enhanced Data rates for
`
`GSM Evolution (EDGE)).
`
`[003]
`
`Presently, EUTRA calls for a random access channel (RACH) protocol
`
`and in particular a physical random access procedure requiring reserved resources for
`
`RACH access. The RACH channel is used for initial access to the network as well as
`
`to transmit small to medium amount of control information and data packets. This
`
`3GPP UMTS specification permits an overall procedure that allows for various
`
`protocol/operational states to suit varying degrees of needed, anticipated, and/or desired
`
`operational activity for transmission of data packets. Unfortunately, for some desired
`
`applications using small of medium amounts of control information and data packets,
`
`the amount of data transmission activity appears to underutilize these reserved RACH
`
`PETITIONERS 1056-0004
`IPR2016-00758
`
`

`

`PATENT APPLICATION
`Attorney Docket No. CEIS637R
`
`[004]
`
`The RACH (random access channel) is essential for initial access to the
`
`network, for the transmission of control information and data packets. The initial
`
`access channel has different names in different systems, such as RACH in the context
`
`of 3GPP, or ranging in the context of IEEE std. 802.166. In this invention, we use
`
`RACH in its general sense to represent the initial access channel of communication
`
`systems.
`
`[005]
`
`It is desired that the RACH include a contention channel, fast acquisition
`
`of preamble, minimization of interference, minimum impact on other scheduled data
`
`transmission, and low data rate transmission for short data/control messages. Several
`
`options are available for multiplexing between the RACH and scheduled-based
`
`channels; Time Division Multiplexing (TDM), Frequency Division Multiplexing
`
`(FDM), and Code Division Multiplexing (CDM). However, in the 3GPP system
`
`problems arise for multiplexing between RACH and scheduled—based channels using
`
`either TDM or FDM. In particular, TDM requires reservation of slots for RACH
`
`access, and FDM requires a frequency (subcarrier) reservation for RACH access. In
`
`either case, a resource reservation is allotted even if there are few RACH requests in the
`
`system, which withholds unused resources that adversely affect system capacity. CDM
`
`transmission, on the other hand, will generate interference to other uplink users.
`
`[006]
`
`To control interference generated by CDM transmission, a MC-CDMA
`
`several figures of which like reference numerals identify identical elements, wherein:
`
`(multi-carrier code division multiple access) technique can be applied for RACH design
`
`without reserving system resources. This invention uses this technique for non-
`
`reserved RACH access of EUTRA communication system.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`[007]
`
`The features of the present invention, which are believed to be novel, are
`
`set forth with particularity in the appended claims. The invention, together with further
`
`objects and advantages thereof, may best be understood by making reference to the
`
`following description, taken in conjunction with the accompanying drawings, in the
`
`PETITIONERS 1056-0005
`IPR2016-00758
`
`

`

`PATENT APPLICATION
`Attorney Docket No. CEI5637R
`
`[008]
`
`FIG. 1 illustrates a TDM/FDM RACH structure;
`
`[009]
`
`FIG. 2 is a table of RACH parameters for the structure of FIG. 1;
`
`[0010]
`
`FIG. 3 is a graphical representation of a circular auto/cross correlation of
`
`a Chu-sequence with M=15, in accordance with the present invention;
`
`[0011]
`
`FIG. 4 is a graphical representation of a correlation sequence in the
`
`invention;
`
`presence of two RACH requests with delays of 0 and 2, in accordance with the present
`
`alarm performance over an AWGN channel, in accordance with the present invention;
`
`[0012]
`
`FIG. 5 is a graphical representation of a detection error rate and false
`
`alarm performance of TDM—RACH over an AWGN channel, in accordance with the
`
`present invention;
`
`[0013]
`
`FIG. 6 is a graphical representation of a detection error rate and false
`
`alarm performance of TDM-RACH over an TU channel at 3 kilometers/hour, in
`
`accordance with the present invention;
`
`[0014]
`
`FIG. 7 is a graph of an example of a RACH preamble, in accordance
`
`with the present invention;
`
`[0015]
`
`FIG. 8 is a block diagram of RACH preamble generation using time-
`
`domain modulation, in accordance with the present invention;
`
`[0016]
`
`FIG. 9 is a block diagram of RACH preamble generation using
`
`frequency-domain modulation, in accordance with the present invention;
`
`[0017]
`
`FIG. 10 is a graphical representation of a circular auto/cross correlation
`
`of a Chu-sequence with M=300, in accordance with the present invention;
`
`[0018]
`
`FIG. 11 is a graphical representation of RACH detection error and false
`
`PETITIONERS 1056-0006
`IPR2016-00758
`
`

`

`PATENT APPLICATION
`
`Attorney Docket No. CE I 563 7R
`
`[0019]
`
`FIG. 12 is a graphical representation of RACH detection error and false
`
`alarm performance over an TU channel at 3 kilometers/hour, in accordance with the
`
`present invention;
`
`[0020]
`
`FIG. 13 is a table showing a comparison of the TDM/FDM and
`
`hybrid/CDM embodiments of the present invention; and
`
`[0021]
`
`FIG. 14 comprises a flow diagram of a method, in accordance with the
`
`present invention; and
`
`10) as shown in FIG. 1. The scheme can use either
`
`Specifically, the RACH preamble is transmitted in a CDM manner, while the message
`
`[0022]
`
`FIG. 15 illustrates a block diagram of a communication system, in
`
`accordance with the present invention.
`
`[0023]
`
`Skilled artisans will appreciate that common but well-understood
`
`elements that are useful or necessary in a commercially feasible embodiment are
`
`typically not depicted in order to facilitate a less obstructed view of these various
`
`embodiments of the present invention.
`
`DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
`
`[0024]
`
`To minimize the performance impact to scheduled users, the present
`
`invention presents a hybrid approach to the RACH preamble in an EUTRA system.
`
`is either scheduled by the Node B in the same manner as regular data transmission,
`
`contention based transmitted, or ACK based transmitted. With proper configuration of
`
`the preamble sequence, the amount of interference generated can be minimized. In
`
`addition, the message portion is scheduled, whereby variable data rates can be
`
`supported with no impact to other uplink users. Moreover, both TDM/FDM and
`
`Hybrid/CDM techniques can be utilized as candidate RACH methods for EUTRA, as
`
`will be detailed below.
`
`[0025]
`
`A RACH preamble can be sequenced using TDM/FDM. In this scheme
`
`a dedicated or special symbol is used for RACH. The RACH symbol can be reserved
`
`every x frames (e.g. x = 1
`
`PETITIONERS 1056-0007
`IPR2016-00758
`
`

`

`PATENT APPLICATION
`Attorney Docket No. CE15637R
`
`localized or distributed mode. In the localized mode the subcarriers are divided into
`
`NR3 resource blocks with each resource block using a fixed number of contigtou's sub-
`
`carriers. Next, for each of the NR3 resource blocks, a number of signature sequence
`
`groups are pre-defined so that every group consists of N5 signature sequences and
`
`different groups can be assigned to different neighboring sectors. Each group also
`
`consists of several cyclically shifted versions of the signature sequences (N511). As
`
`such, the total number of RACH opportunities per DFT—SOFDM symbol is given by
`
`NR3 *NS* NSH.
`
`[0026]
`
`As an example for 5MHz bandwidth, all 300 subcarriers are divided into
`
`twenty resource blocks with NR3 =20. A RACH signature sequence occupies fifieen
`
`subcarriers corresponding to 225kHz bandwidth, thus the length of a signature
`
`sequence is fifteen. For the scalable bandwidth structure, the length of a signature
`
`sequence is fixed to fifteen. The number of RACH opportunities thus varies according
`
`to different bandwidth deployments. Detailed numerology is shown in FIG. 2 for a set
`
`of scalable bandwidth.
`
`in FIG. 2. The total RACH overhead is dependent on the reserved RACH access rate.
`
`amplitude zero autocorreleation (CAZAC) sequence, which include different “classes”
`
`[0027]
`
`Dividing the RACH opportunities into resource blocks provides the
`
`opportunity to take advantage of channel frequency selective characteristics to further
`
`improve the performance. The user equipment (UE) chooses the best available
`
`resource blocks for RACH‘preamble transmission based on information of the current
`
`frequency selective nature of the channel.
`
`[0028]
`
`In general, the signature sequences are obtained from a constant
`
`of generalized chirp like (GCL) or Chu-sequences which are complex valued and have
`
`unit amplitude. The GCL/Chu sequence has low cross correlation at all time lags
`
`which improves the detection performance. As used herein, the CAZAC, Chu and
`
`GCL sequences can be used interchangeably.
`
`[0029]
`
`The numbers of RACH groups for different bandwidths are summarized
`
`PETITIONERS 1056-0008
`IPR2016-00758
`
`

`

`PATENT APPLICATION
`Anomey Docket No. CEIS637R
`
`For example, if the RACH access is reserved every 1 millisecond, the RACH overhead
`
`is 1/l4=7.1%.
`
`[0030]
`
`Specific RACH preamble sequencing can be defined. Since the
`
`sequence length equals to fifteen, a Chu-sequence can be selected which is defined as
`
`-J'2—”lpn(n+l)
`gn=e “2
`
`, n=0,l,...,M—l
`
`with a Walsh sequence of length two, d) signature sequences with combined spreading
`
`uplink interference generated is minimal (e.g. 27.8dB reduction with a spreading gain
`
`where M=I5, andp is relatively prime to M. In this case, p = {l,2,4,7,8,l1,13,14,...}.
`
`For a fixed p, the Chu-sequence is orthogonal to its time-shift. For a different p, Chu-
`
`sequences are not orthogonal.
`
`The circular autocorrelation and cross-correlation
`
`properties of a Chu sequence is shown in FIG. 3. FIG.3 shows that Chu sequence has
`
`optimal autocorrelation property, while its cross-correlation has relatively small value
`
`for different delays.
`
`[0031]
`
`If the preamble is detected at the Node-B, the Node-B sends an
`
`ACKnowledge. Upon detection of the ACK at the UE, the UE sends the message part
`
`in the next slot using the same resource block (RB) location which was used to send the
`
`preamble. As an alternative, if the system is lightly loaded the message can be
`
`scheduled as outlined below.
`
`[0032]
`
`In accordance with the present invention, a hybrid/CDM approach is
`
`used for the RACH preamble configuration. To minimize uplink interference, the
`
`RACH preamble is designed to use time-frequency spreading with a long spreading
`
`factor. With this approach, no reservation of symbols and sub-carriers are required and
`
`of 600). In addition, a simple receiver structure with frequency domain processing can
`
`be used to process the preamble. The RACH preamble structure is summarized as
`
`follows: a) the preamble length is l millisecond using two 0.5 millisecond sub-frames;
`
`a total of 4200 chips excluding Cyclic Prefix length, b) frequency spreading with
`
`spreading factor M using a Chu-sequence (complex quadratic sequence), where M is
`
`the occupied sub-carriers excluding DC (direct current) component , 0) time spreading
`
`PETITIONERS 1056-0009
`IPR2016-00758
`
`

`

`PATENT APPLICATION
`
`Attorney Docket No. CE I 5637R
`
`factor 2XM out of which a total of twenty are'used, and e) a repetition of seven is used
`
`to rate-match the preamble sequence length to one millisecond.
`
`[0033]
`
`The Chu-sequence (complex quadratic sequence) or GCL sequence is
`
`given by
`
`and the delayed Chu—sequence is given by
`
`g4,» = g(n—30d)modM : d = 0,---9
`
`Note that the Chu-sequence is a special sequence of the GCL sequence class. Other
`GCL sequences can be applied as the signature sequence as well. For example, for
`even M, we can define g, as
`
`millisecond.
`
`.27!
`a
`.
`—J*“P"'—I—'Pq”
`gn=e M2
`M
`
`, n=o,...,M_1
`
`where p is an integer relatively prime to M, and q is any integer.
`
`To provide temporal spreading, a Walsh sequence of length two is used; w=0, 1. The
`
`sequence is given by
`
`w° = {+1,+1}, w' = {+1,—l}
`
`To generate the twenty unique signature sequences, a sequence identifier s is first
`
`computed via s = 2 Xd +k where d=0, ...9 corresponds to the delay of the Chu-sequence.
`
`and k=0,1 is the index of the Walsh sequence. The resulting s-th RACH preamble
`
`signature sequence (with length 2M) is then given by
`
`P5 = [Wk(0)gd,. wk<l)g,,_n+M],
`
`n = O,...,M —I
`
`An example of the RACH preamble sequence is shown in FIG. 7.
`
`In this case, d=5,
`
`and k=1 with a resulting sequence index number of eleven. The sequence P1 1, made up
`
`of g5,n and —g5,,, (i.e. Walsh code {1,-1}) is then repeated seven times in order to cover 1
`
`PETITIONERS 1056-0010
`IPR2016-00758
`
`

`

`PATENT APPLICATION
`Anomey Docket No. CE15637R
`
`[0034]
`
`To mitigate inter-cell interference of RACH channel, different Chu-
`
`sequences or GCL sequences can be used for different sectors/cells. A generalized
`
`Chu-sequence is given by:
`
`n=l,...,M—l
`
`where p is chosen such that the greatest common divisor ofp and M is 1. For example,
`
`when M: 300, andp represents the prime numbers {1,7,11,13,17,19,23,29,31,37,...}.
`
`Given a fixed p, the corresponding Chu-sequence is orthogonal when it is shifted
`
`circularly. However, the sequences are not orthogonal for different p and behave as
`
`random sequences. Thus, by assigning different p to different sector/cell, inter-cell
`
`transmit power of the CDM RACH preamble is significantly less (20-30 dB lower) per
`
`interference can be mitigated.
`
`[0035]
`
`RACH preamble generation can be accomplished using either time-
`
`domain modulation (FIG. 8) or frequency-domain generation (FIG. 9). In time-domain
`
`modulation, a message symbol is mixed with a frequency-spreading sequence as
`
`described herein in accordance with the present invention. The combined signal is then
`
`processed using time-spreading, followed by a Discrete Fourier Transform (DFT),
`
`mapping, Inverse Fast Fourier Transform (IFFT), and Cyclic Prefix (CP), as are known
`
`in the art. In frequency-domain modulation is first processed using time-spreading,
`
`which is copied to multiple paths, as are known in the art. These different paths are
`
`then mixed with frequency—spreading sequence as described herein in accordance with
`
`the present invention. The combined signals are then processed by an Inverse Fast
`
`Fourier Transform (IFFT), and Cyclic Prefix (CP), as are known in the art.
`
`[0036]
`
`The circular autocorrelation and cross correlation properties for M=300
`
`is shown in FIG. 10. This figure illustrates an optimal property of circular
`
`autocorrelation and good cross correlation performance of Chu-sequence with length
`
`300. FIGS. 11 and 12 show the RACH preamble detection error rate and false alarm
`
`rate for AWGN and TU (typical urban) channel. The RACH preamble detection is
`
`outlined above. In this case, BW=5 MHz, corresponding to a Chu-sequence of length
`
`300. Compared to the power requirement for data transmission, it is seen that the
`
`PETITIONERS 1056-0011
`IPR2016-00758
`
`

`

`PATENT APPLICATION
`Attorney Docket No. CE15637R
`
`user. As a result, interference generated by the RACH preamble is expected to be
`
`insignificant for lightly loaded system.
`
`[0037]
`
`The RACH preamble detection is similar to the detection algorithm of
`
`TDM/FDM-based RACH at a Node-B. The block-by-block detection utilizes
`
`frequency-domain correlation, which is suitable for Frequency Domain Equalization
`
`(FDE). There is no time—domain correlation needed, which makes calculations less
`
`complex. For example, assume an UE randomly selects a RACH preamble sequence
`
`with sequence identifier number s. The 2M length RACH sequence is
`
`PS =[w"(0)gd,,, wk(1)gd,n+M],
`
`n = 0,...,M—l
`
`where s = 2Xd +k. At
`
`the receiver side of Node-B,
`
`the received signal can be
`
`represented as
`
`y" =x,, ®hn+zn,
`
`where ®indicates circular convolution, h” is channel
`
`impulse response, 2,,
`
`is the
`
`channel noise, and x,, is either wk(0)gd,n or wk(l)gd‘n.
`
`[0038]
`
`At the receiver the circular (periodic) correlation of sequence g" and
`
`y,,.is computed. This yields
`
`.
`_1
`n:
`Cm = W 20 yng(n-m)modM
`
`For 5MHz bandwidth
`
`where the term z,,,’ is the equivalent channel noise. Usually the channel maximum
`
`The correlation can be performed either in time or frequency domain. Through some
`
`simple manipulations, the following is obtained
`
`cm =
`
`\thWw + 2;,
`‘
`—JMhm_30d + zm
`
`k = 0
`
`,
`
`k =1
`
`delay is assumed to be less than the length of cyclic prefix. Here, it is assumed that the
`
`maximum channel delay is less than thirty signal chips.
`
`PETITIONERS 1056-0012
`IPR2016-00758
`
`

`

`PATENT APPLICATION
`Attorney Docket No. CE15637R
`
`deployment, the length of thirty chips using current E-UTRA numerology equals to
`
`6.67 microseconds.
`
`[0039]
`
`Since there are two Walsh sequence for k=0 and k=I , one can combine
`
`the nearby two blocks for both Walsh sequences. There are a total of fourteen blocks
`
`of which one 2M RACH sequence uses two blocks. Two neighbor c,,. are added to
`
`yield seven correlation sequences for k=0. For k=I , two neighbor c,,. are subtracted
`
`accordingly to yield another seven correlation sequences for k=1. In the next step, we
`
`detect the delay index d, so that the RACH sequence identifier number s (s = 2 >'<d +k)
`
`can be obtained.
`
`[0040]
`
`From the correlation sequence cm, when a RACH request with delay
`
`index d is present, the channel impulse response will appear in the frame {30d,
`
`30d+30}, as illustrated in FIG. 4. The figure shows two RACH requests with sequence
`
`delay 0 and sequence delay 2. The correlation sequence cm indicates corresponding
`
`channel impulse response at {0-30} and {60-90} regions. By detecting power in
`
`different regions, one can thus detect the RACH preamble at the Node-B.
`
`[0041]
`
`It is possible to have a ML (maximum likelihood) optimal detection of
`
`the RACH request if the channel impulse response is known. However, usually such
`
`channel information is not available to the receiver at the Node-B. A simple detection
`
`algorithm is the maximum power detection. When the maximum power in a certain
`
`region is greater than a power threshold, a RACH request corresponding to that region
`
`is assumed.
`
`[0042]
`
`The detection algorithm has three steps. First, calculate average power
`
`of correlation sequence. This yields
`
`power threshold 77,, . Thus,
`
`The second step is to find the maximum power in all regions to obtain
`2
`
`1 Sod-+29
`= = max C
`P m=30d I MI
`
`.
`
`rd
`
`The final step is to check whether the maximum power is greater than a pre-defined
`
`PETITIONERS 1056-0013
`IPR2016-00758
`
`

`

`PATENT APPLICATION
`
`Attorney Docket No. CE15637R
`
`[0043]
`
`With the detected d, and its corresponding Walsh code index k, the
`
`RACH sequence identifier number s, can be obtained through 5 = 2d +k.
`
`[0044]
`
`The above technique detects the received power based on correlation of
`
`the received sequence to all the possible sequences. The correlation can be carried out
`
`either in time or frequency domain. Once the detected power is greater than a pre-
`
`defined power threshold, a RACH preamble is detected. Naturally, the choice of
`
`threshold determines detection performance. FIGS. 5 and 6 illustrate detection
`
`performance of the TDM/FDM RACH preamble under AWGN and TU (typical urban)
`
`propagation channels, respectively. The following definitions were used in the
`
`performance evaluation: a) false alarm refers to a scenario where a particular code was
`
`detected when nothing or a different code was transmitted, and b) detection error refers
`
`rd 2 7m RACH request with delay d is present
`H < 7",
`RACH request with delay d is absent '
`
`monitor the downlink control channel for possible downlink data transmission.
`
`to when a particular code was transmitted but not detected.
`
`[0045]
`
`To maximize capacity utilization in the uplink, there are three
`
`approaches for RACH message transmission. At first, RACH message transmission
`
`can be scheduled by the Node B on a time-frequency region reserved specifically for
`
`RACH message transmissions. These regions are fixed and known beforehand so as to
`
`minimize control message overhead. The frequency, size, and number of these RACH
`
`messages regions will depend on system design and deployment scenarios. Naturally,
`
`when there is no RACH message transmission, the Node B can schedule other users in
`
`these time-frequency regions. At the Node B, once the RACH preamble is successfully
`
`received, a four-bit acknowledgement corresponding to the sequence number is
`
`transmitted to the UE. This is done even when the UE may not be scheduled for some
`
`time to prevent the UE from transmitting the RACH preamble again. Subsequent to
`
`receiving an acknowledgement, the UE monitors the downlink control channel for a
`
`period of time for scheduling information in order to transmit the RACH message. Due
`
`to the use of micro-sleep mode, power consumption from monitoring the downlink
`
`control channel is not expected to be an issue. In addition, the UE may already need to
`
`PETITIONERS 1056-0014
`IPR2016-00758
`
`

`

`PATENT APPLICATION
`Attorney Docket No. CE15637R
`
`[0046]
`
`The second RACH message transmission approach can be contention
`
`based. Once UE receives ACK from Node-B for RACH access, UE sends the RACH
`
`message in the predefined channel. Then UE can further monitor downlink control
`
`channel for fiirther ACK information for the transmitted RACH message.
`
`[0047]
`
`The third RACH message transmission approach is ACK based. With
`
`this approach, a resource block for message transmission is reserved by Node-B once
`
`needed. The RACH ACK information indicates the readiness of the reserved channel.
`
`Once UE receives this ACK information, the RACH message is sent in the reserved
`
`channel.
`
`signature sequences, which is used 1406 in a preamble for a RACH. Preferably, the
`
`interchangeably with ‘mobile station’, and that ‘base station’, ‘BTS’ and ‘node-B’ can
`
`[0048]
`
`FIG. 13 compares the RACH features between the TDM/FDM technique
`
`and the Hybrid/CDM embodiments of the present invention.
`
`[0049]
`
`Referring to FIG. 14, the present invention also provides a method for
`
`random channel access between a user equipment (UE) and a Node-B of a EUTRA
`
`communication system, as shown in FIG. 15, wherein the UE 1500 reserves and
`
`transmits information on the RACH channel 1516, and the Node-B1502 receives the
`
`information on the RACH channel. However it should be recognized that the present
`
`invention is applicable to other systems including 3GPP, 3GPP2, and 802.16
`
`communication systems, and that the terms ‘user equipment’ can be used
`
`be used interchangeably, as are known in the art. The UE 1500 includes a transmitter
`
`1504, receiver 1506, and processor 1508 coupled thereto. The node-B 1502 also
`
`includes a transmitter 1510, receiver 1512, and processor 1514 coupled thereto.
`
`[0050]
`
`In a first step, the UE 1500 defines 1400 a plurality of spread sequences
`
`derived from a plurality of constant amplitude zero autocorrelation (CAZAC)
`
`sequences. Specifically, the sequences can be Chu-sequences or GCL sequences. In
`
`addition, the sequence may be delayed. The UE then combines 1402 the spread
`
`sequences with an orthogonal code (e. g. Walsh code) to form extended spread
`
`sequences (signature sequences). In a next step, the UE selects 1404 one of the
`
`PETITIONERS 1056-0015
`IPR2016-00758
`
`

`

`PATENT APPLICATION
`
`Attorney Docket No. CE1563 7R
`
`selection is randomly selected. However, the select sequence could be predefined or
`
`selected to reduce the possibility of interference.
`
`[0051]
`
`The UE then determines an available RACH access slot and other
`
`transmission parameters. In a next step, the UE sets 1408 a transmission power. In a
`
`next step, the UE transmits 1410 the RACH preamble using the selected slot, signature
`
`sequence, and power, and then monitors 1412 for a positive acquisition indicator
`
`(ACKnowledgement) from the node-B 1502. If no positive acquisition indicator is
`
`detected, in a next step, the UE may wait 1414 for a period of time or the UE changes
`
`1416 transmission power with a new access slot and a new randomly selected signature
`
`until the maximum number of transmissions or maximum power is reached. If positive
`
`acquisition indicator is detected, in a next step, the UE sends 1418 RACH message to
`
`Node-B. FIG. 16 illustrates the procedure of preamble detection in Node-B 1502.
`
`Node—B detects 1420 preamble until the preamble is detected 1422. Then the RACH
`
`ACK is sent 1424 to UE. The next step will be the RACH message transmission.
`
`[0052]
`
`There are three approaches for RACH message transmission. The
`
`details of message transmitting 1418 in UE and message receiving 1426 in Node-B will
`
`be illustrated in FIG. 17, 18, and 19.
`
`’
`
`scheduled. Node—B schedules 1436 RACH message transmission after the RACH ACK
`
`[0053]
`
`FIG. 17 is the method of schedule-based RACH message transmission.
`
`UE monitors 1430 the downlink control channel for a fixed amount of time to obtain
`
`1432 scheduling information for the RACH message. The Node-B can be signaled for
`
`RACH message transmission, and the RACH message can then be sent 1434 as
`
`is sent. Node—B will receive 1438 RACH message at its scheduled time and frequency.
`
`[0054]
`
`FIG. 18 is the method of contention-based RACH message transmission.
`
`UE sends 1440 the RACH message upon RACH ACK is received. In the next step, UE
`
`listens 1442 the downlink control channel for RACH message ACK to determine 1444
`
`whether the message is received by Node—B. Node-B will receive 1446 RACH
`
`message after the RACH ACK is sent. When the message is received 1448, a RACH
`
`message ACK should be sent 1450.
`
`PETITIONERS 1056-0016
`IPR2016-00758
`
`

`

`PATENT APPLICATION
`Attorney Docket No. CE15637R
`
`[0055]
`
`FIG. 19 is ACK-based RACH message transmission approach. A
`
`RACH message channel is reserved. UE will wait 1452 for RACH MSG (message)
`
`the RACH message is sent 1454. Node-B monitors the availability of the RACH
`
`message channel. It will send 1456 MSG ACK and receive 1458 RACH message in
`
`the next step.
`
`ACK from Node-B for clear of RACH message channel. Once the channel is available,
`
`logical or physical structure or organization.
`
`[0056]
`
`Advantageously, the present invention provides a CDM type of RACH
`
`with a MC-CDMA approach in the EUTRA system. There is no reservation of time
`
`slots or sub-carriers involved, which results in zero RACH overhead. The present
`
`invention has the capability of working at very low transmitting power (L=6OO
`
`spreading gain), and any interference introduced in minimal (spreading gain L=600
`
`results in 27.8dB reduction). In addition, a simple receiver configuration can be used
`
`with frequency domain processing.
`
`[0057]
`
`The present invention provides the advantage of enhancing capacity of
`
`the E-UTRA system pursuant to the above embodiments. In particular, providing the
`
`RACH preamble sequencing without the need for reserved RACH access resources
`
`enhances the peak rate of data transmission and can reduce latency issues for data
`
`t