Title of Invention

A METHOD FOR GENERATING A GROUP IDENTIFIER OF THE RANDOM ACCESS RESPONSE MESSAGE AND A RANDOM ACCESS METHOD

Abstract The invention discloses a method for generating a group identifier of the random access response message. The group identifier is determined according to the serial number of the subframe in which the random access time slot of random access preamble message transmitted by the terminal lies and the serial number of the random access channel in which the random access time slot lies. A random access method and a random access response method in a cellular radio communication system are also provided. Using the method of the present invention, the terminal needs not acquire the absolute system time of the cellular system in which the random access time slot lies, and can access the cellular radio communication system rapidly and accurately.
Full Text

TECHNICAL FIELD
The invention relates to the field of cellular radio communications, and more specifically
to a method for generating a group identifier of the random access response message and
a random access method.
BACKGROUND
As shown in Fig. 1, a cellular radio communication system mainly comprises terminals,
base stations and a core network (CN). A radio access network (RAN) is a network
formed by the base stations and responsible for the transaction of the access layer, for
example, the management of the radio resources, etc. A physical or logical connection
may exist among the base stations according to the actual conditions, for example, the
connection between the base station 1 and the base station 2 or between the base station 1
and the base station 3 shown in Fig. 1. Each base station can be connected with one or
more core network nodes. The core network is responsible for the transaction of a
non-access layer, for example, the location updating, etc., and it is an anchor point of the
user plane. The terminals refer to various devices for communicating with the cellular
radio communication network, for example, mobile telephones or notebook computers, etc.
The cellular radio communication system takes a radio frame as the basic unit for
identification of the system time, the serial number of the radio frame is known as radio
frame number (SFN). The terminal can acquire the boundary of the radio frame through a
cell search method, thereby achieving time synchronization on a downlink. In the cellular
radio communication system such as the Long Term Evolution (LTE) system , the length of
the radio frame is 10ms (millisecond), and as shown in Fig. 2, as to the Frequency Division
Duplex (FDD) mode, 10 subframes are included in one radio frame, the time length of each
subframe is 1ms, each subframe includes two time slots, and the time length of each time
slot is 0.5ms; as shown in Fig. 3, as to the Time Division Duplex (TDD) mode, generally


speaking, one frame includes two half frames of which the time length is 5ms, each half
frame includes 5 subframes, the time length of each subframe is 1ms, except for subframe
#1 and subframe #6, other subframes also include two time slots, wherein the time length of
the subframe and the time slot are the same with that in the FDD mode respectively;
subframe #1 and subframe #6 respectively include 3 special time slots, i.e., DwPTS, GP
and UpPTS. Subframe #6 can also be a normal subframe in some TDD frame formats, as
shown in Fig. 4.
As to the LTE system, the length of a normal random access time slot is 1ms, i.e.,
occupying the length of one subframe, and in addition, an extended random access time
slot is also introduced, which may occupy the length of 2 or 3 subframes. A short random
access time slot is also introduced in the TDD mode, i.e., transmitting on the UpPTS time
slot.
As to the FDD mode, any subframe in time domain can be configured as a random
access time slot, but only one random access channel exists on one random access time
slot. One random access channel occupies the bandwidth of 6 radio resource blocks (RB)
in frequency domain. As to the TDD mode, subframe #0 and subframe #5 are always
downlink time slots in time domain, therefore, subframe #0 and subframe #5 cannot be
configured as random access time slots, the UpPTS time slots in subframe #1 and
subframe #6 can be configured as random access time slots, whether other time slots
except for the above can be configured as random access time slots is determined by the
method of configuring an uplink time slot and a downlink time slot in the TDD frame
structure, that the time slots configured as uplink subframes can be taken as the random
access time slot. As to the TDD mode, one or more random access channels can exist on
one random access time slot.
In the prior LTE system, the process of the terminal accessing into the cellular radio
communication system comprises three steps as follows:


Step a, the terminal transmits a random access preamble message to the base station
though a certain random access time slot of the radio frame;
Step b, the base station responds the terminal with a random access response
message;
Step c, the terminal determines whether a correct response message is received
according to the group identifier in the random access response message and the index of
the random access preamble.
In step a, one or more terminals may transmit random access preamble messages to
the base station though the same random access time slot, that these random access
preamble messages may be the same with or different from each other, and the base
station can identify the different random access preamble messages on the same random
access time slot.
In step b, the random access response message may contain response information in
response of one or more random access preamble messages. These random access
preamble messages are all transmitted though the same random access time slot.
Probably more than one random access response messages are merged into one
response message, mainly in order to improve the utilization ratio of the radio resources in
the random access process. In order to enable the terminal to identify the random access
response messages, the base station adds a group identifier in the message, and there is a
corresponding relationship between the group identifier and the random access time slot
though which the random access preamble message is transmitted. Meanwhile, the
random access response message may also contain an individual identifier corresponding
to the random access preamble message itself, which is usually an index number of the
random access preamble. The method for setting the group identifier is regulated in the


protocol in advance, and when certain terminal transmits the random access preamble
message to the base station, it has already been known what group identifier and individual
identifier are to be received.
To ensure that the random access response process has certain flexibility, the random
access response message is not synchronous with the random access preamble message,
i.e., there is no fixed relationship between the two in time domain; on the contrast, the
random access response message is allowed to be transmitted in a time window. At the
same time, to increase the flexibility of the scheduling of the radio sources, to respond the
random access preamble message received though certain random access time slot, the
base station can transmit the random access response message corresponding to the
random access preamble message on one or more Transmission Time Intervals (TTIs) in
the time window. The start time of the time window is related to the speed of the base
station to process the random access preamble message, and its end time is related to the
load of the base station to process the random access preamble message and the radio
resources scheduled to the random access response message, and other factors.
In step c, after the terminal receives one random access response message in the
specified time window, firstly, the terminal verifies whether the expected group identifier is
included in the message; if the expected group identifier is included in the message, the
terminal then verifies whether the individual identifier (for example, index number)
corresponding to the transmitted random access preamble message is also included in the
response message; if the expected individual identifier (for example, index number) is
included, it can be determined that the current random access response message
corresponds to the transmitted random access preamble message.
In the prior art, a method for setting the group identifier in step b is provided. Generally,
in these methods a group identifier is calculated according to the absolute location of the
random access time slot in the system time, therefore the group identifier is unique within


the specified time range. These methods have the disadvantages that firstly, the terminal
need to acquire the absolute system time of the cellular system in which the random access
time slot lies, which generally refers to SFN, however, in real application, for example, the
SFN of the target cellular system may be not known by the terminal in advance during the
handover process, the group identifier cannot be calculated, and extra delay and system
processing, for example, reading the system message, are usually needed to acquire the
SFN of the target cellular system, because the SFN is usually broadcast in the system
message.
SUMMARY
The technical problems that the invention aims to solve is to provide a method for
generating a group identifier of the random access response message and a random
access method, so that the terminal accesses into the cellular radio communication system
rapidly and accurately.
To solve the problems above, the invention provides a method for generating a group
identifier of the random access response message, and the group identifier is determined
according to the serial number Sn of the subframe in which the random access time slot of
the random access preamble message transmitted by the terminal lies and the serial
number m of the random access channel in which the random access time slot lies.
Further, the group identifier may be determined according to the following formula:
group identifier = Sn + m x 10.
Further, when the random access time slot is an extended random access time slot, the
serial number Sn of the subframe in which the random access time slot lies may refer to the
serial number of the subframe at the start position in a plurality of subframes occupied by
the random access time slot.


To solve the problems above, the invention also provides a random access method for
the cellular radio communication system. The terminal transmits the random access
preamble message to the base station though the random access time slot and then
detects the random access response message corresponding to the random access
preamble message in the time window; the random access response message includes a
group identifier; the group identifier is determined according to the serial number Sn of the
subframe in which the random access time slot lies and the serial number m of the random
access channel in which the random access time slot lies.
Further, the group identifier may be determined according to the following formula:
group identifier = Sn + m x 10.
Further, the terminal may read the parameter of the time window for random access in a
common signaling, and the common signaling may include system messages; or the
terminal may read the parameter of the time window for random access in a dedicated
signaling, and the dedicated signaling may include handover command messages.
Further, when the random access time slot is an extended random access time slot, the
serial number Sn of the subframe in which the random access time slot lies may refer to the
serial number of the subframe at the start position in a plurality of subframes occupied by
the random access time slot.
To solve the problems above, the invention also provides a random access response
method for the cellular radio communication system. The base station receives the random
access preamble message transmitted by the terminal though the random access time slot
and then transmits the random access response message corresponding to the random
access preamble message in the time window; the random access response message
includes a group identifier; and the group identifier is determined according to the serial


number Sn of the subframe in which the random access time slot lies and the serial number
m of the random access channel in which the random access time slot lies.
Further, the group identifier may be determined according to the following formula:
group identifier = Sn + m x 10.
Further, when the random access time slot is an extended random access time slot, the
serial number Sn of the subframe in which the random access time slot lies may refer to the
serial number of the subframe at the start position in a plurality of subframes occupied by
the random access time slot.
By using the method of the invention, the terminal can access into the cellular radio
communication system rapidly and accurately, the determining of the group identifier in the
random access response message by the terminal is not depended upon the reading of the
SFN, and this is especially important for the random access process during the handover
process. In addition, no matter how the configuration of the random access time slot
changes, the same method can be adopted for setting the group identifier, and the
operation is easy for realization.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a structure diagram illustrating the cellular radio communication system in the
prior art;
Fig. 2 illustrates the structure of a radio frame in the LTE FDD mode in the prior art;
Fig. 3 illustrates the structure of a radio frame in the LTE TDD mode in the prior art;


Fig. 4 illustrates the structure of another radio frame in the LTE TDD mode in the prior
art;
Fig. 5 is a flowchart of the random access method for the cellular radio communication
system of the embodiment in the invention.
DETAILED DESCRIPTION
In the invention, the terminal transmits the random access preamble message to the
base station though the random access time slot and then detects the random access
response message corresponding to the random access preamble message in the time
window; the corresponding random access response message includes a group identifier,
and the group identifier is determined according to the serial number of the subframe in
which the random access time slot lies and the serial number of the random access
channel in which the random access time slot lies.
Preferably, the group identifier is determined according to the following formula:
Group Identifier = Sn + m x 10.
Wherein, the parameter Sn refers to the serial number of the subframe in which the
random access time slot lies, and the parameter m refers to the serial number of the
random access channel in which the random access time slot lies.
The technical scheme of the invention will be described in detail in conjunction with the
embodiments and accompanying drawings as follows.
As shown in Fig. 5, the random access method for the cellular radio communication
system comprises the following steps:


Step 501, the terminal transmits the random access preamble message to the base
station through the random access time slot, and in the light of the predetermined method
for generating the group identifier, the group identifier expected to be received is
determined according to the serial number of the subframe in which the random access
time slot lies and the serial number of the random access channel in which the random
access time slot lies;
Step 502, the base station determines the group identifier of RA-RNTI (Random
Access-Radio Network Temporary Identifier) in the light of the same method for generating
the group identifier that is used by the terminal, then adds the group identifier together with
the individual identifier corresponding to the random access preamble message into the
random access response message, and then transmits the random access response
message to the terminal;
Step 503, when the terminal detects and determines in the time window that the group
identifier in the received random access response message and the index of the random
access preamble are the expected values respectively determined by the terminal, the
terminal determines that the random access response message is the response message
corresponding to the random access preamble message transmitted by the terminal.
In step 502, the random access response message also includes uplink radio resources
allocated to the terminal by the base station; in step 503, after determining the receiving of
the expected random access response message, the terminal transmits message or data
to the base station through the uplink radio resources.
In step 503, the parameter of the time window for receiving the random access
response message by the terminal can be read in a common signaling by the terminal, and


the common signaling includes system messages; or be read in a dedicated signaling by
the terminal, and the dedicated signaling includes handover command messages.
In step 501 or step 502, the method for generating the group identifier comprises:
The group identifier is determined according to the serial number Sn of the subframe in
which the random access time slot of the random access preamble message transmitted by
the terminal lies and the serial number m of the random access channel in which the
random access time slot lies.
The group identifier can be directly determined according to the following formula:
RA-RNTI = Sn + mx10 (1)
Wherein, Sn refers to the serial number of the subframe in which the random access
time slot in the radio frame lies; when the random access time slot is an extended random
access time slot, Sn refers to the serial number of the subframe at the start position in a
plurality of subframes occupied by the random access time slot; in the TDD mode, if the
random access time slot occupies the UpPTS time slot, Sn refers to the serial number of
subframe #1 and subframe #6;
m refers to the serial number of the random access channel in which the random access
time slot lies. In the FDD mode, only one random access channel is configured, and m is
always 0; in the TDD mode, a plurality of random access channels can be configured, and
m may be greater than 0;
In addition, to determine the group identifier, a range value N can be used in conjunction
with the serial number Sn of the subframe in which the random access time slot lies and the
serial number m of the random access channel in which the random access time slot lies,


and the range value N can be determined according to the time window parameter
configured by the network and can also be a constant.
When the range value N is 10, the generation of the group identifier is determined only
according to the serial number Sn of the subframe in which the random access time slot lies
and the serial number m of the random access channel in which the random access time
slot lies.
The RA-RNTI corresponding to the random access time slot is determined according to
the following formula:
RA-RNTI = RA-RNTI-COUNT + Sn%N + m x N (2)
Wherein, the parameters Sn and m have been described above and thus, the detailed
description thereof will be omitted herein.
The range value N can be determined according to the length of the time window for
receiving the random access response message by the terminal. For example, when the
length of the time window is equal to or less than 5, the range value N is 5; otherwise, the
range value N is 10; the range value N can also be a constant (fixed value) such as 2, 5 or
10. The length of the time window is configured by the system, and the terminal acquires
the length of the time window through a dedicated signaling (for example, handover
command) or a common signaling (for example, system message).
% indicates a modulus operator, and Sn%N indicates the modulus of Sn to N, i.e., the
remainder obtained by exactly dividing Sn with N.


RA-RNTI-COUNT is a constant set by the system, and the constant has the same
length with the identification C-RNTI configured to the terminal by the system, i.e., the
occupied bits are the same. The value of RA-RNTI-COUNT can be set to be 0.
It can be understood that when N=0, and RA-RNTI-COUNT=0, the formula (2) above is
simplified as follows:
RA-RNTI = Sn%10 + mx 10 (3)
Since Sn is ranged from 0 to 9, Sn%10=Sn, i.e., the formula (3) is identical to the
formula (1):
RA-RNTI = Sn + mx 10
This can be further described by the following detailed embodiments:
The generation of the group identifier is determined according to the formula (1):
As to the FDD mode, the value of m is 0, then RA-RNTI= Sn; therefore the RA-RNTI
corresponding to the random access preamble message transmitted on subframe #2(i.e.,
Sn=2) is 2; the RA-RNTI corresponding to the random access preamble message
transmitted on subframe #8(i.e., Sn=8) is 8.
As to the TDD mode, it is assumed that 4 random access channels are configured, and
the RA-RNTI corresponding to the random access preamble message transmitted on
subframe #2(i.e., Sn=2) in random access channel #0 (m=0) is 2+0*10, i.e., 2; the
RA-RNTI corresponding to the random access preamble message transmitted on
subframe #8(i.e., Sn=8) in random access channel #3(m=3) is 8+3*10, i.e., 38.


The generation of the group identifier is determined according to the formula (2):
As to the FDD mode, the value of m is 0, the received time window is assumed to be 4,
then N=5, the RA-RNTI corresponding to the random access preamble message
transmitted on subframe #3(i.e., Sn=3) is RA-RNTI-COUNT+3%5, i.e.,
RA-RNTI-COUNT+3; the RA-RNTI corresponding to the random access preamble
message transmitted on subframe #7(i.e., Sn=7) is RA-RNTI-COUNT+7%5, i.e.,
RA-RNTI-COUNT+2.
As to the TDD mode, it is assumed that 3 random access channels are configured, the
receiving time window is 6, N=10, and then RA-RNTI corresponding to the random access
preamble message transmitted on subframe #3(Sn=3) in random access channel #0(m=0)
is RA-RNTI-COUNT+3%10+0*10, i.e., RA-RNTI-COUNT+3; the RA-RNTI corresponding
to the random access preamble message transmitted on subframe #7(Sn=7) in random
access channel #2(m=2) is RA-RNTI-COUNT+7%10+2*10, i.e., RA-RNTI-COUNT+27.
It is assumed that the RA-RNTI-COUNT involved in the formula (2) is 0X2008
(represented in hexadecimal format).
Specific embodiment 1: in the FDD mode, the length of the receiving time window is
assumed to be 4ms, N=5, the serial number of the subframe on which the random access
preamble message was transmitted is Sn, then,
RA-RNTI=0X2008 + Sn%5, wherein Sn is ranged from 0 to 9.
When Sn=3, RA-RNTI = 0X2008+3 = 0X200B
When Sn=6, RA-RNTI = 0X2008+1 = 0X2009


Specific embodiment 2: in the TDD mode, the length of the receiving time window is
assumed to be 6ms, N=10; the serial number of the subframe in which the time slot for
transmitting the random access preamble lies is Sn, and the serial number of the random
access channel in which the time slot for transmitting the random access preamble lies is m,
then:
RA-RNTI = 0X2008 + Sn%10 + m x 10, wherein the range of Sn is 1, 2, 3, 4, 6, 7, 8 and
9.
When m=0, and Sn=1, RA-RNTI = 0X2008 + 1=0X2009
When m=1, and Sn=3, RA-RNTI = 0X2008 + 3 + 10=0X2015
When m=2, and Sn=6, RA-RNTI = 0X2008 + 6 + 20=0X2022
In the above formulas, the operation of the hexadecimal 0X2008 being directly added to
the decimal Sn%10 and m x10 aims to easily understand formula (2).
Although the invention has been described with reference to the specific embodiments,
those skilled in the art should understand that various modifications and variations can be
made without departing from the spirit or scope of the invention. It is intended that all
these modifications and variations fall within the scope of the invention and the protection of
the claims attached with the invention.
INDUSTRIAL APPLICABILITY
The invention provides a method for generating a group identifier of the random access
response message and a random access method and a random access response method
in a cellular radio communication system. The terminal need not acuquire the absloute


system time of the cellular radio communication system in which the random access time
slot lies and can access into the cellular radio communication system rapidly and accurately.
Furthemore, no matter how the configuration of the random access time slot changes, the
same method can be adopted for setting the group identifier, and the operation is easy for
realization.


WE CLAIM :
1. A method for genrating a group identifier of the random access response
message, comprising the following steps: the group identifier being determined
according to a serial number Sn of a subframe in which a random access time slot of a
random access preamble message transmitted by a terminal lies and a serial number
m of a random access channel in which the random access time slot lies.
2. The method according to claim 1, wherein the group identifier is determined
according to the following formula: group Identifier = Sn + m x 10, or group Identifier
= RA-RNTI-COUNT + Sn%N + m x N, where RA-RNTI-COUNT is a constant set by a
system.
3. The method according to claim 1 or 2, wherein when the random access time
slot is an extended random access time slot, the serial number Sn of the subframe in
which the random access time slot lies refers to the serial number of the subframe at
the start posiiton in a plurality of subframes occupied by the random access time slot.

4. A random access method for the cellular radio communication system,
comprising the following steps: a terminal transmitting a random access preamble
message to a base station though a random access time slot, and then detecting a
random access response message corrsponding to the random access preamble
message in a time window; the random access response message including a group
identifier; the group identifier being determined according to a serial number Sn of a
subframe in which the random access time slot lies and a serial number m of a random
access response channel in which the random access time slot lies.
5. The method according to claim 4, wherein the group identifier is determined
according to the following formula: group Identifier = Sn + m x 10, or group Identifier


= RA-RNTI-COUNT + Sn%N + m x N, where RA-RNTI-COUNT is a constant set by a
system.
6. The method according to claim 4 or 5, wherein the terminal reads the parameter
of the time window for random access in a common signaling, and the common
signaling includes system messages; or the terminal reads the parameter of the time
window for random access in a dedicated signaling, and the dedicated signaling
includes handover command messages.
7. The method according to claim 4 or 5, wherien when the random access time
slot is an extended random access time slot, the serial number Sn of the subframe in
which the random access time slot lies refers to the serial number of the subframe at
the start position in a plurality of subframes occupied by the random access time slot.
8. A random access response method for the cellular radio communication system,
comprising the following steps: a base station receiving a random access preamble
message transmitted by a terminal though a random access time slot and then
transmitting a random access response message corrsponding to the random access
preamble message in a time window; the random access response message
including a group identifier; and the group identifier being determined according to a
serial number Sn of a subframe in which the random access time slot lies and a serial
number m of a random access channel in which the random access time slot lies.
9. The method according to claim 8, wherein the group identifier is determined
according to the following formula: group Identifier = Sn + m x 10, or group Identifier
= RA-RNTI-COUNT + Sn%N + m x N, where RA-RNTI-COUNT is a constant set by a
system.

10. The method according to claim 8 or 9, wherein when the random access time
slot is an extended random access time slot, the serial number Sn of the subframe in
which the random access time slot lies refers to the serial number of the subframe at
the start position in a plurarity of subframes occupied by the random access time slot.


The invention discloses a method for generating a group identifier of the random access
response message. The group identifier is determined according to the serial number of
the subframe in which the random access time slot of random access preamble message
transmitted by the terminal lies and the serial number of the random access channel in
which the random access time slot lies. A random access method and a random access
response method in a cellular radio communication system are also provided. Using the
method of the present invention, the terminal needs not acquire the absolute system time of
the cellular system in which the random access time slot lies, and can access the cellular
radio communication system rapidly and accurately.

Documents:

http://ipindiaonline.gov.in/patentsearch/GrantedSearch/viewdoc.aspx?id=CS5iMy0OAB6IcWYgbM8qiQ==&loc=wDBSZCsAt7zoiVrqcFJsRw==


Patent Number 278044
Indian Patent Application Number 3951/KOLNP/2010
PG Journal Number 52/2016
Publication Date 16-Dec-2016
Grant Date 09-Dec-2016
Date of Filing 22-Oct-2010
Name of Patentee ZTE CORPORATION
Applicant Address ZTE PLAZA, KEJI ROAD SOUTH, HI-TECH INDUSTRIAL PARK, NANSHAN, SHENZHEN, GUANGDONG, 518057, CHINA
Inventors:
# Inventor's Name Inventor's Address
1 DU, ZHONGDA ZTE PLAZA, KEJI ROAD SOUTH, HI-TECH INDUSTRIAL PARK, NANSHAN, SHENZHEN, GUANGDONG, 518057, CHINA
2 YU, BIN ZTE PLAZA, KEJI ROAD SOUTH, HI-TECH INDUSTRIAL PARK, NANSHAN, SHENZHEN, GUANGDONG, 518057, CHINA
PCT International Classification Number H04Q 7/38
PCT International Application Number PCT/CN2008/072258
PCT International Filing date 2008-09-03
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 200810087530.9 2008-03-25 China