WO2005094189A2

WO2005094189A2 - Method of scheduling an uplink packet transmission channel in a mobile communication system

Info

Publication number: WO2005094189A2
Application number: PCT/KR2005/000916
Authority: WO
Inventors: Joon Kui Ahn; Hak Seong Kim; Seung Hwan Won
Original assignee: Lg Electronics Inc.
Priority date: 2004-04-02
Filing date: 2005-03-30
Publication date: 2005-10-13
Also published as: AU2005227794A1; RU2006138609A; MXPA06011129A; CN102858020B; EP2375640A1; US20050220116A1; KR20050097726A; AU2005227794B2; EP2375640B1; CN102858020A; EP1730897B1; WO2005094189A3; EP1730897A2; JP2007531453A; US7551625B2; CN1943174A; WO2005094189A8; US20090262711A1; ATE511725T1; US8139549B2

Abstract

A method of scheduling an uplink packet transmission channel in a mobile communication system is disclosed. The method of scheduling includes determining a scope of user equipments (UEs) to be applied to a scheduling assignment for scheduling the uplink packet transmission channel (S32, S34), and transmitting the scheduling assignment to the user equipments included in the determined scope (S33, S35, S36), wherein the scheduling assignment includes an identifier for identifying the scope of the user equipments and scheduling contents for carrying information applicable to the scheduling assignment. Preferably, said scope of user equipments is determined by the status of the uplink packet trasmission channel (S31) and according to the determined scope the scheduling assigment is either transmitted to each UE (S33), to a group of UEs (35) or to all UEs (36).

Description

METHOD OF SCHEDULING AN UPLINK PACKET TRANSMISSION CHANNEL IN A MOBILE COMMUNICATION SYSTEM

Technical Field

The present invention relates to a method of scheduling in wireless packet

communication system, and more particularly, to a method of scheduling uplink

packets in wireless communication system. Although the present invention is suitable

for a wide scope of applications, it is particularly suitable for transmitting scheduling

information to specified groups of subscribers or to all subscribers.

Background Art

With increasing demand in speed and size of uplink transmission, methods of

high-speed packet communication during the uplink from a mobile device to a base

station are widely being discussed. E-DCH (Enhanced uplink Dedicated CHannel) of

3GPP WCDMA (3^rd Generation Partnership Project, Wideband Code Division

Multiple Access) is an example of one ofthe methods being discussed.

The E-DCH incorporates existing methods such as uplink packet scheduling from

Node B (base station) in the 3GPP WCDMA uplink DCH (Dedicated CHannel) and

HARQ (Hybrid Automatic Retransmission reQuest) in the Physical Layer (PHY) to

increase the efficiency of uplink transmission. Through efficient construction of

scheduling assignment from Node B, the system processing rate is increased. Node B controlled scheduling is one ofthe methods that is applicable to the

existing 3GPP WCDMA E-DCH. According to current discussions on standards,

techniques such as Time Division Multiplex (TDM), Code Division Multiplex (CDM),

or time and code division multiplex can be used to transmit Node B scheduling

assignment (Similar to High Speed Downlink Packet Access (USDPA)). If any ofthe

three techniques are used, scheduling assignment transmitted to each user equipment

(UE) contains at least UE classification identification (UE ID) and the contents of

scheduling assignment.

Each UE inspects the downlink channel which is used to transmit scheduling

assignment via UE ID. Ifthe UE ascertains that the scheduling assignment transmitted

as a part of UE ID is correctly addressed, the UE acquires the contents ofthe

scheduling assignment. According to the scheduling assignment, the UE starts,

terminates, or holds transmission. Since the scheduling assignment is transmitted from

Node B to each UE, a substantial amount of time is required to transmit the same

scheduling assignment to a specified group of UEs or to all the UEs.

As discussed above, scheduling assignments are independently transmitted using

time division, code division, or time-code division techniques to each UE.

Consequently, a problem arises in transmitting scheduling assignments to a specified

group(s) of UEs or to all the UEs in the PHY. In addition, transmitting using such

techniques to individual UE causes traffic congestion due to sudden increase in uplink

traffic in the PHY and cannot be dealt with quickly. Disclosure of Invention

Accordingly, the present invention is directed to a method of scheduling an uplink

packet transmission channel in a mobile communication system that substantially

obviates one or more problems due to limitations and disadvantages ofthe related art. An object of the present invention is to provide a method of scheduling an uplink

packet transmission channel in a base station of a mobile communication system.

Another object of the present invention is to provide a method scheduling an

uplink packet transmission channel to efficiently deal with communication traffic

congestion problems. A further object of the present invention is to provide a method of scheduling an

uplink packet transmission channel to transmit scheduling assignment, not only to

individual user equipments, but also to a group of user equipments and/or to all user

equipments.

Additional advantages, objects, and features of the invention will be set forth in

part in the description which follows and in part will become apparent to those having

ordinary skill in the art upon examination of the following or may be learned from

practice of the invention. The objectives and other advantages of the invention may be

realized and attained by the structure particularly pointed out in the written description

and claims hereof as well as the appended drawings. To achieve these objects and other advantages and in accordance with the purpose

ofthe invention, as embodied and broadly described herein, a method of scheduling an

uplink packet transmission channel in a base station is provided. In the method of scheduling an uplink packet transmission channel, a scope of user equipments (UEs) of

a scheduling assignment for scheduling the uplink packet transmission channel is

determined. Furthermore, the scheduling assignment to user equipments included in

the determined scope is transmitted. Also, the scheduling assignment includes an user

equipment identifier which identifies the scope ofthe user equipments, and scheduling

contents for carrying information applicable to the scheduling assignment. hi another aspect of the present invention, a method of scheduling an uplink

packet transmission channel in an user equipment (UE) is provided. In the method of

scheduling an uplink packet transmission, The UE receives a scheduling assignment

transmitted from a base station. Also, the scheduling assignment includes an user

equipment identifier which identifies a scope of user equipments for the scheduling

assignment. In addition, the scheduling assignment includes scheduling contents for

carrying information applicable to the scheduling assignment and for transmitting

packets through the uplink packet transmission channel according to the scheduling

assignment.

It is to be understood that both the foregoing general description and the

following detailed description of the present invention are exemplary and explanatory

and are intended to provide further explanation ofthe invention as claimed.

Brief Description of Drawings

The accompanying drawings, which are included to provide a further

understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) ofthe invention and together with the description

serve to explain the principle ofthe invention, hi the drawings;

FIG. 1 shows scheduling assignment channels allocated along a timeline;

FIG. 2 illustrates grouped scheduling assignment channels; and FIG. 3 is a flowchart for determining a method of transmitting a scheduling

assignment.

Best Mode for Carrying Our the Invention

Reference will now be made in detail to the preferred embodiments ofthe present

invention, examples of which are illustrated in the accompanying drawings. Wherever

possible, the same reference numbers will be used throughout the drawings to refer to

the same or like parts.

Although the preferred embodiment ofthe present invention relates to an E-DCH,

the present invention can be applied to voluntary wireless packet communication

system.

An Enhanced Absolute Grant Channel (E-AGCH) is a downlink channel used by

a base station (Node B) to send a scheduling command to an user equipment (UE). In

other words, Node B transmits a command as to how much transmission power or a

level of data rate transmission an UE is permitted to transmit. This is also known as

uplink scheduling assignment or scheduling assignment.

Under E-AGCH, each frame of the downlink transmission from Node B of

scheduling assignment includes UE identifier (UE ID) and scheduling content. The UE ID is used to identify the receiving UE of the scheduling assignment for an uplink

packet transmission.

The scheduling content includes various information such as scheduled power,

duration, and priority. The scheduled power, also referred to as rate, defines a

maximum amount of power that can be allotted for transmission of the uplink packet

transmission. Furthermore, duration refers to how long the scheduling assignment

remains effective in each UE while priority refers to a certain limitation assigned to the

uplink packet transmission. For example, if Node B transmits a scheduling assignment

to UE 1 with priority of C, where the order of alphabet starting with A indicating the

highest priority of transmission, UEl transmits when it is its time to transmit. In other

words, UEl transmits when it is time for UEs having priority C to transmit. Each

scheduling assignment can also include any combination of information such as UE ID,

scheduled power, and priority or UE ID, scheduled power, and duration. h E-AGCH, scheduling assignment(s) can be transmitted from Node B via shared

channel(s) to an UE, group(s) of UEs, or all the UEs. The transmitted scheduling

assignment is then shared by all the UEs. In E-AGCH, the UEs of the shared channel

receive and decode the transmitted scheduling assignment. After receipt and decoding

of the scheduling assignment by the UEs of the shared channel, based on the UE ID

included in a transmission packet of the scheduled assignment, the scheduled

assignment is followed by the UE(s) whose ID corresponds to the ID(s) of the

transmission. For example, assuming there are four UEs (UEl - UE4), Node B

fransmits via a shared channel a scheduling assignment, which applies only to UEl, to all four UEs. All four UEs receive, decode, and identify to which UE(s) the

transmission is directed, the transmission, in the packet of the scheduling

assignment would contain an UE ID that corresponds only to the ID of UEl. Therefore,

the scheduling assignment would be followed only by UEl and not by any other UEs.

This example could also apply to groups of UEs. hi addition, under E-AGCH, each UE can have more than one UE identifier. Here,

each UE can have an identifier for a scheduling assignment directed to the

corresponding UE, and another identifier for a scheduling assignment forwarded by

another UE which received the initial scheduling assignment from Node B. In other

words, an UE identifier for following a scheduling assignment transmitted from Node

B as well as another UE identifier for following a scheduling assignment forwarded by

another UE in the shared channel. Such forwarding of scheduling assignment can

reduce and minimize transmission in the channel between Node B and UE(s). A

number of identifiers an UE can possess is not limited to two identifiers as explained

above but can have many more for various purposes.

For example, continuing from the previous example, after the UEs receive and

decodes the scheduling assignment transmitted from Node B which is directed to UE4,

the UE4 is further instructed to fransmit the scheduling assignment to all UEs in the

shared channel, i.e., UEl, UE2, UE3, and UE4. This time, the scheduling assignment is

not from Node B but from another UE which received the initial assignment. Upon

receipt of the scheduling assignment from UE4, all the UEs in the shared channel

would receive and decode the assignment, as did with the assignment from Node B. Here, the scheduling assignment has identified UEl, UE2, and UE4 to follow. By

having another UE identifier in each UE, Node B can direct the scheduling assignment

intended for multiple UEs to a single UE and have that UE further transmit to other

intentded UEs so as to minimize transmission ofthe same scheduling assignment. Under Enhance Relative Grant Access Channel (E-RGCH), unlike E-AGCH,

Node B has a pre-allocated channel of transmission, and the scheduling assignment is

transmitted accordingly. In E-RGCH, the scheduling assignment is comprised of at

least 1 bit, and ID is not transmitted as part of the transmission packet information.

Subsequently, the UE receiving the scheduling assignment via the pre-allocated

channel reads and follows the assignment. For example, assuming there are four UEs

(UEl - UE4), Node B transmits a scheduling assignment, which applies only to UEl,

to only UEl. Because the fransmission channels are pre-allocated, transmissions to the

remaining UEs are not made.

In addition, E-RGCH is not limited to transmitting scheduling assignment to a

single UE at a time. Under E-RGCH, it is possible to pre-allocate a plurality of

channels to transmit a same scheduling assignment to a plurality of UEs. For example,

continuing from the previous example, if Node B has pre-allocated channels 1 and 2

which apply to UEl and UE2, respectively, to transmit the same scheduling

assignment, the same scheduling assignment would then be transmitted only to UE 1

and UE2 and not to other UEs (UE3 and UE4). Only UEl and UE2 would receive and

follow the scheduling assignment. As discussed above, the differences between E-AGCH and E-RGCH is clear.

Under E-AGCH, a scheduling assignment is received by all UEs in a shared channel

regardless to which UE the scheduling assignment is directed. However, the

scheduling assignment would apply only to the UEs having the IDs corresponding to

the IDs designated in the scheduling assignment. Under E-RGCH, the transmission

channel(s) are pre-allocated by Node B, and only the UE(s) of the pre-allocated

channel(s) would receive the scheduling assignment(s). The UE(s) not having been

pre-allocated by Node B would not receive the scheduling assignment(s).

An embodiment of the present invention will be further explained with respect to

E-AGCH. Node B utilizes various transmission techniques such as code division, time

division, and code-time division methods to transmit scheduling assignment to UEs via

scheduling assignment channels (Ch-1 - Ch-n). The scheduling assignment includes

contents and UE IDs' of each UE, UE IDs' of specified group(s), or an UE ID that

applies to all the UEs uniformly. More specifically, scheduling content refers to the

command transmitted from Node B to UEs which include information such as packet

transmission power (Tx_Power), Transmit Format Combination (TFC), packet

transmission time. As explained above, UE ID is an identifier used to identify an UE or

a group of UEs for transmitting scheduling assignment.

The operation of Node B in determining the scheduling assignment for UE(s) is as

follows. At each transmit time interval (TTI), Node B determines the status of the

uplink packet fransmission channel. To accomplish this, various techniques can be

employed such as Signal-to-Noise Ratio (SNR), Signal-to-Interference-plus-Noise Ratio (SINR) and Rise over Thermal noise (RoT). For example, RoT can be used to

determine the uplink channel status. Here, Node B determines the RoT value based on

the status ofthe uplink channel. The determined RoT value is then compared to at least

one critical value. A critical value is set in a manner not to exceed a maximum RoT

value permitted in the communication system. Based on whether the determined RoT

value exceeds the critical value, Node B determines whether to transmit scheduling

assignment to each UE, group(s) of UEs, or all the UEs. Although one critical value

was used in the above example, a plurality of critical values can be used to determine

the method of transmitting scheduling assignment(s). Moreover, as discussed above, a

method of determining the uplink channel status is not limited to using RoT, and other

methods can be used.

In Figure 3, an example having two critical values (RoTt_M, RoT_th2, except RoT_t _

> RoT_th2) are used to further explain scheduling assignment. The first step (S31) begins

by first determining RoT value at every TTI of scheduling assignment. The RoT value

can be defined by calculating the power of receiving signals over thermal noise in the

base station. After the RoT value is determined, the determined RoT value is compared

with the RoT_thi value (S32). Usually, the RoT value corresponds to noise/interference,

hence when the noise/interference is low, the RoT value becomes large since the

thermal noise compared to the power of receiving signal is small. On the contrary, if

the noise/interference is high, the RoT value becomes small since the thermal noise

compared to the power of receiving signal is large. If the determined RoT value is larger or equal than the RoT_th_ value (RoT >

RoT_thi), which denotes low noise/interference, a scheduling assignment is transmitted

to each UE (S33). When the transmission of scheduling assignment is made, the UE ID

is used to define the receiving UE, and the scheduling contents are used to transmit

command for the UE to follow.

If the determined RoT value is larger than RoT_t _ value, the determined RoT

value is then compared to the RoT_th2 value. Since it was determined in the previous

step that the determined RoT value is larger than RoTt_h_, Node B determines if the

determined RoT value is smaller than or equal to the value of RoT_th2 (RoT_h2 ≤RoT <

RoTt_h (S34). If so, the determined RoT value is smaller than RoT_thi value but larger

or equal to than RoT_th₂ value, h such a case, the scheduling assignment(s) is/are

fransmitted to a group or groups of UEs, containing the UE ID and the scheduling

contents (S35). The UE group IDs allow the UEs ofthe group to identify a scheduling

assignment directed to them as a group. The UE group IDs can be pre-established

using various techniques between Node B and the UEs.

Ifthe determined RoT value is smaller than RoT_th₂ (RoT < RoTt_h2), which denotes

high interference, therefore the low RoT value, the same scheduling assignment,

including scheduling contents and an UE ID, is transmitted to all the UEs (S36). Using

RoT value is one of many methods of determining the status of the uplink packet

transmission channel. As mentioned above, other techniques such as SNR and SINR

can also be used. Figure 1 shows a numerous scheduling assignment channels during different time

frames per each channel. Here, each channel can fransmit individual scheduling

assignment as well as different sets of groups of scheduling assignments and the all the

scheduling assignments grouped as one. hi other words, different types of scheduling

assignments are transmitted at different times.

As presented in Figure 1, Ch-1 - Ch-n are, for example, orthogonal variable

spreading factor (ONSF) code channels. In particular, n represents number of UEs

capable of performing simultaneous decoding operation. Furthermore, SAi (i=l-n)

represents scheduling assignment transmitted to i^th UE, SA-Gi (i=l-k) represents

scheduling assignment transmitted to i^th group of UEs, and SA-all represents

scheduling assignment transmitted to all the UEs.

Figure 2 shows transmitting scheduling assignments to UEs as multiple groups or

as a group consisting all the UEs. As discussed above, based on the noise/interference

of the uplink packet transmission channel as determined by Node B, the scheduling

assignment commands the uplink packet transmission.

As shown in Figure 2, Node B can transmit scheduling assignments to n number

of UEs in groups as indicated by SA-GI and SA-G2. At the same time, scheduling

assignments can be transmitted to all UEs simultaneously as indicated by SA-all. h

transmitting scheduling assignments, specific UE ID(s) directed for specific group(s)

of UEs or for all UEs are fransmitted along with scheduling contents. It is possible to transmit scheduling assignment to all the UEs using a separate or

different channel than the channels used to transmit scheduling assignments to each

UEs separately or to specific groups of UEs.

It is also possible to include in the scheduling assignment a command which

grants or denies packet fransmission. hi other words, Node B determines either to grant

or deny packet fransmission depending on the status of channels. Subsequently, traffic

congestion in the channels and shortage of resources can be alleviated, promoting

efficiency ofthe entire system.

It will be apparent to those skilled in the art that various modifications and

variations can be made in the present invention without departing from the spirit or

scope of the inventions. Thus, it is intended that the present invention covers the

modifications and variations of this invention provided they come within the scope of

the appended claims and their equivalents.

Claims

1. A method of scheduling an uplink packet transmission channel in a base

station, comprising: determining a scope of user equipments (UEs) to be applied to a scheduling

assignment for scheduling the uplink packet transmission channel; and transmitting the scheduling assignment to the user equipments included in the

determined scope, wherein the scheduling assignment comprises an identifier for identifying the

scope of the user equipments and scheduling contents for carrying information

applicable to the scheduling assignment.

2. The method of claim 1, wherein the scope of the user equipments

includes the UE, a group of UEs, or all UEs.

3. The method of claim 1, further comprising determining a status of the

uplink packet transmission channel, wherein the scope of UE is determined by the

status ofthe uplink packet transmission channel.

4. The method of claim 1, wherein the status of the uplink packet

transmission chamiel is determined by using Rise over Thermal (RoT) value which is

power of receiving signals over thermal noise in the base station.

5. The method of claim 4, wherein the RoT value is compared to at least

one pre-selected critical value.

6. The method of claim 5, wherein the scheduling assignment is

transmitted to each UE ifthe RoT value is larger or equal to than a first critical value.

7. The method of claim 5, wherein the scheduling assignment is

fransmitted to a group of UEs if the RoT value is smaller than the first critical value

but larger than or equal to a second critical value.

8. The method of claim 5, wherein a same scheduling assignment is

fransmitted to all UEs ifthe RoT value is smaller than the second critical value.

9. The method of claim 1, wherein the scheduling contents include a

scheduled power command for assigning a specified amount of power for the uplink

packet transmission channel.

10. The method of claim 1, wherein the scheduling contents include a

duration command for determining a length of period the scheduling assignment

remains effective.

11. The method of claim 8, wherein the scheduling contents include a

priority command for defining a certain limitation of transmission in the uplink packet

transmission channel in the scheduling assignment.

12. The method of claim 1, wherein the uplink packet fransmission channel

is an Enhanced Dedicated Channel (E-DCH).

13. The method of claim 1, wherein the scheduling assignment includes a

command granting or denying transmission in the uplink packet transmission channel.

14. The method of claim 1, further comprising transmitting the scheduling

assignment to a group of UEs or all UEs via a shared channel in Enhanced Absolute

Grant Channel, wherein the scheduling assignment is received and decoded by each

UE ofthe group of UEs or all the UEs ofthe shared channel.

15. The method of claim 1, further comprising transmitting the scheduling

assignment to a specific UE according to a pre-allocated fransmission channel in

Enhanced Relative Grant Channel, wherein the specific UE corresponds with the pre-

allocated transmission channel.

16. The method of claim 15, wherein the scheduling assignment can be

transmitted to a plurality of UEs according to corresponding plurality of pre-allocated

fransmission channels.

17. A method of scheduling an uplink packet transmission channel in an

user equipment (UE), comprising: receiving a scheduling assignment transmitted from a base station, wherein the

scheduling assignment comprises an identifier identifying a scope of user equipments

for the scheduling assignment and scheduling contents for carrying information

applicable to the scheduling assignment; and transmitting packets through the uplink packet transmission channel according

to the scheduling assignment.

18. The method of claim 17, wherein the scope of user equipments includes

the UE, a group of UEs, or all UEs.

19. The method of claim 17, wherein the scheduling contents include a

packet transmission.

20. The method of claim 17, wherein the scheduling contents include a

duration command for determining a length of period the scheduling assignment

remains effective.

21. The method of claim 17, wherein the scheduling contents include a

transmission channel in the scheduling assignment.

22. The method of claim 17, wherein the uplink packet transmission

channel is an Enhanced Dedicated Channel (E-DCH).

23. The method of claim 17, wherein the scheduling assignment includes a

command granting or denying transmission in the uplink packet fransmission channel.

24. The method of claim 17, wherein each UE of a shared channel in

Enhanced Absolute Grant Channel has at least one UE identifier.

25. The method of claim 24, wherein at least one UE identifier applies to an

individual UE, a group of UEs, or all UEs.

26. A method of scheduling an uplink packet transmission channel in a

mobile communication system, comprising: determining a scope of user equipments (UEs) to be applied to a scheduling

assignment for scheduling the uplink packet transmission channel; transmitting the scheduling assignment to the user equipments included in the

determined scope; receiving the scheduling assignment transmitted from a base station; and transmitting packets through the uplink packet transmission channel according

to the scheduling assignment, wherein the scheduling assignment comprises an identifier for identifying the

scope of the user equipments and scheduling contents for carrying information

applicable to the scheduling assignment.

27. The method of claim 26, wherein the scope of the user equipments

includes the UE, a group of UEs, or all UEs

28. The method of claim 26, further comprising determimng a status of the

status ofthe uplink packet transmission channel.

29. The method of claim 26, wherein the status of the uplink packet

fransmission channel is determined by using Rise over Thermal (RoT) value which is

power of receiving signals over thermal noise in the base station.

30. The method of claim 29, wherein the RoT value is compared to at least

one pre-selected critical value.

31. The method of claim 30, wherein the scheduling assignment is

32. The method of claim 30, wherein the scheduling assignment is

transmitted to a group of UEs if the RoT value is smaller than the first critical value

but larger than or equal to a second critical value.

33. The method of claim 30, wherein a same scheduling assignment is

transmitted to all UEs ifthe RoT value is smaller than the second critical value.

34. The method of claim 26, wherein the scheduling contents include a

packet transmission channel.

35. The method of claim 26, wherein the scheduling contents include a

duration command for determining a length of period the scheduling assignment

remains effective.

36. The method of claim 26, wherein the scheduling contents include a

transmission channel in the scheduling assignment.

37. The method of claim 26, wherein the uplink packet transmission

channel is an Enhanced Dedicated Channel (E-DCH).

38. The method of claim 26, wherein the scheduling assignment includes a

39. The method of claim 26, further comprising transmitting the scheduling

UE ofthe group of UEs or all the UEs ofthe shared channel.

40. The method of claim 26, further comprising transmitting the scheduling

assignment to a specific UE according to a pre-allocated transmission channel in

allocated transmission channel.

41. The method of claim 40, wherein the scheduling assignment can be

fransmitted to a plurality of UEs according to corresponding plurality of pre-allocated

fransmission channels.

42. The method of claim 26, wherein each UE of a shared channel in

Enhanced Absolute Grant Channel has at least one UE identifier.

43. The method of claim 42, wherein at least one UE identifier applies to an

individual UE, a group of UEs, or all UEs.