Apparatus and method for scheduling in a multi-hop relay wireless communication system

• US 20090075587A1
• Filed: 09/12/2008
• Published: 03/19/2009
• Est. Priority Date: 09/19/2007
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Kim, Yung-Soo, Cho, Myeon-Kyun, Yu, Tak-Ki, Min, Chan-Ho
• Granted Patent: US 8,670,716 B2
• Time in Patent Office: Days
• US Class Current: 455/7
• CPC Class Codes: H04B 7/2606 Arrangements for base station coverage control, e.g. by using relays in tunnels
• CPC Class Codes: H04W 72/121 for groups of terminals or users
• CPC Class Codes: H04W 72/542 using measured or perceived quality
• CPC Class Codes: H04W 84/047 using dedicated repeater stations

Abstract

A multi-hop relay wireless communication system is provided. A base station (BS) includes a communication unit for receiving information on a received signal level and information on an interference node from mobile stations (MSs), and a scheduler for classifying a type of each MS by using the received signal level information and the interference node information and for performing differentiated scheduling according to the MS type.

Claims

1. A base station (BS) apparatus in a multi-hop relay wireless communication system, the apparatus comprising:

a communication unit for receiving a received signal level information and an interference node information from a plurality of mobile stations (MSs); and

a scheduler for classifying a type of each mobile station by using the received signal level information and the interference node information and for performing a differentiated scheduling according to the mobile station type.

2. The apparatus of claim 1, wherein the scheduler comprises:

a classifier for classifying the mobile station type; and

an allocator for allocating one or more resources in an exclusive manner to a group of at least one type-1 mobile station and at least one type-2 mobile station and for allocating one or more resources of a predetermined region to at least one type-3 mobile station.

3. The apparatus of claim 2, wherein the classifier classifies the mobile station type according to:

$\mathrm{type}<br><br>\text{-}<br><br>1<br><br>\text{;<br><br>}<br><br><br><br>\frac{P_S}{\underset{j=1}{\overset{l}{\sum <br><br>}}<br><br>P_I^j}><br><br>{\mathrm{Th}}_1,<br><br>\mathrm{type}<br><br>\text{-}<br><br>2<br><br>\text{;<br><br>}<br><br><br><br>\frac{P_S}{\underset{j=1}{\overset{L}{\sum <br><br>}}<br><br>P_{I<br><br>\text{-}<br><br>\mathrm{intra}}^j}><br><br>{\mathrm{Th}}_2,<br><br>\mathrm{type}<br><br>\text{-}<br><br>3<br><br>\text{;<br><br>}<br><br><br><br>\frac{P_S}{\underset{j=1}{\overset{L-M}{\sum <br><br>}}<br><br>P_{I<br><br>\text{-}<br><br>\mathrm{inter}}^j}><br><br>{\mathrm{Th}}_3,$

where P_S denotes a received signal level from a serving node, L denotes a number of remaining nodes included in an active set other than the serving node, P_l-intra^j denotes a received signal level from a j^th internal cell, P_l-inter^j denotes a received signal level from a j^th external cell, and Th_k denotes a type-k threshold.

4. The apparatus of claim 2, wherein the allocator allocates the one or more resources within a region, which is prohibited in use in a cell neighboring to the type-3 mobile station and which is included in the predetermined region, to at least one type-3 mobile station.

5. The apparatus of claim 2, wherein the scheduler comprises:

a manager for configuring a mobile station pool for at least one type-1 mobile station and at least one type-2 mobile station so that at least one remaining mobile station to be scheduled other than at least one grouped mobile station is included in a selection candidate list;

a calculator for calculating a metric of each mobile station included in the mobile station pool;

a selector for selecting a mobile station having a greatest metric and for removing at least one mobile station having an interference relation with the selected mobile station; and

a determining unit for determining at least one mobile station selected by the selector as one group.

6. The apparatus of claim 5, wherein the selector repeats the selecting and the removing of the mobile station until all mobile stations included in the mobile station pool are removed or selected.

7. The apparatus of claim 6, wherein the calculator calculates the metric according to one of the following equations:

${\mathrm{SM}}_k={\mathrm{SINR}}_k;<br><br><br><br>\mathrm{maximum}<br><br><br><br>\mathrm{SINR}<br><br><br><br>\mathrm{scheme},<br><br>{\mathrm{SM}}_k<br><br>\left(i\right)=\frac{R_k<br><br>\left(i\right)}{T_k^{\mathrm{\alpha <br><br>}}<br><br>\left(i\right)};<br><br>\mathrm{proportional}<br><br><br><br>\mathrm{fairness}<br><br><br><br>\mathrm{scheme},\text{<br><br>}<br><br>T_k<br><br>\left(i+1\right)=\{\begin{array}{c}<br><br>\mathrm{\beta <br><br>}<br><br><br><br>T_k<br><br>\left(i\right)<br><br>\text{;<br><br>}<br><br><br><br>\mathrm{non}<br><br>\text{-}<br><br>\mathrm{scheduled}<br><br><br><br>\mathrm{at}<br><br><br><br>\mathrm{time}<br><br><br><br>i\\ <br><br>\mathrm{\beta <br><br>}<br><br><br><br>T_k<br><br>\left(i\right)+\left(1-\mathrm{\beta <br><br>}\right)<br><br>R_k<br><br>\left(i\right)<br><br>\text{;<br><br>}<br><br><br><br>\mathrm{scheduled}<br><br><br><br>\mathrm{at}<br><br><br><br>\mathrm{time}<br><br><br><br>i,\end{array}$

where SM_k denotes a scheduling metric of a k^th mobile station, SINR_k denotes a signal to interference and noise ratio (SINR), T_k(i) denotes an average data rate of the k^th mobile station at a time i, α

denotes a scaling constant, and β

denotes a forgetting constant.

8. The apparatus of claim 7, wherein the calculator calculates the metric of each mobile station in an initial stage of scheduling in which the mobile stations to be scheduled are determined.

9. The apparatus of claim 6, wherein the calculator calculates the metric by using the scheduling metric of each mobile station according to a corresponding scheduling scheme and by using a reuse matrix (RM) representing an interference relation between the base station and a relay station (RS).

10. The apparatus of claim 9, wherein the calculator calculates the metric according to:

$f<br><br>\left({\mathrm{SM}}_k,\mathrm{RM}\right)={\mathrm{SM}}_k+N_{\mathrm{BS}-\mathrm{RS}}<br><br>\left(\mathrm{RM}\right)\times <br><br>\underset{j=1}{\overset{N_{\mathrm{RS}-\mathrm{pool}}}{\sum <br><br>}}<br><br>\mathrm{Avg}<br><br>\left[{\mathrm{SM}}^j\right],$

where SM_k denotes a scheduling metric of a k^th mobile station, RM denotes a reuse matrix (RM), f(•

) denotes a reuse-based scheduling metric, N_BS-RS(RM) denotes an average number of base stations or relay stations that can be additionally selected when the k^th mobile station is selected, and Avg[SM^j] denotes an average value of scheduling metrics of mobile stations dependent on a j^th RS.

11. The apparatus of claim 10, wherein the calculator calculates the metric of each mobile station whenever each of the mobile stations is selected.

12. A mobile station (MS) apparatus in a multi-hop relay wireless communication system, the apparatus comprising:

a measurer for measuring a received signal level from a base station (BS) and a relay station (RS) by using a received signal;

a processor for determining a serving node and at least one interference node and for generating a control information comprising an interference node information and a received signal level information; and

a communication unit for transmitting the control information.

13. A scheduling method of a base station (BS) in a multi-hop relay wireless communication system, the method comprising:

receiving an information on the received signal level information and the interference node information from one or more mobile stations (MSs);

classifying a type of each mobile station by using the received signal level information and the interference node information; and

performing a differentiated scheduling according to the mobile station type.

14. The method of claim 13, wherein performing a differentiated scheduling comprises:

allocating one or more resources in an exclusive manner to a group of at least one type-1 mobile station and at least one type-2 mobile station; and

allocating one or more resources of a predetermined region to at least one type-3 mobile station.

15. The method of claim 14, wherein the mobile station type is classified according to:

$\mathrm{type}<br><br>\text{-}<br><br>1<br><br>\text{;<br><br>}<br><br><br><br>\frac{P_S}{\underset{j=1}{\overset{l}{\sum <br><br>}}<br><br>P_I^j}><br><br>{\mathrm{Th}}_1,<br><br>\mathrm{type}<br><br>\text{-}<br><br>2<br><br>\text{;<br><br>}<br><br><br><br>\frac{P_S}{\underset{j=1}{\overset{L}{\sum <br><br>}}<br><br>P_{I<br><br>\text{-}<br><br>\mathrm{intra}}^j}><br><br>{\mathrm{Th}}_2,<br><br>\mathrm{type}<br><br>\text{-}<br><br>3<br><br>\text{;<br><br>}<br><br><br><br>\frac{P_S}{\underset{j=1}{\overset{L-M}{\sum <br><br>}}<br><br>P_{I<br><br>\text{-}<br><br>\mathrm{inter}}^j}><br><br>{\mathrm{Th}}_3,$

where P_S denotes a received signal level from a serving node, L denotes a number of remaining nodes included in an active set other than the serving node, P_l-omtra^j denotes a received signal level from a j^th internal cell, P_l-inter^j denotes a received signal level from a j^th external cell, and Th_k denotes a type-k threshold.

16. The method of claim 14, wherein allocating one or more resources of a predetermined region to at least one type-3 mobile station comprises allocating resources within a region, which is prohibited in use in a cell neighboring to at least one type-3 mobile station and which is included in the predetermined region, to at least one the type-3 mobile station.

17. The method of claim 14, wherein performing a differentiated scheduling comprises:

configuring a mobile station pool for at least one type-1 mobile station and at least one type-2 mobile station so that at least one remaining mobile station to be scheduled other than at least one grouped mobile station is included in a selection candidate list;

calculating a metric of each mobile station included in the mobile station pool;

selecting a mobile station having a greatest metric and removing at least one mobile station having an interference relation with the selected mobile station; and

determining at least one mobile station selected by the selector as one group.

18. The method of claim 17, further comprising:

after removing the mobile station having an interference relation with the selected mobile station, if there is a mobile station which is unremoved or unselected, repeating the selecting and the removing of the mobile station; and

if all mobile stations included in the mobile station pool are removed or selected, determining at least one selected mobile station as one group.

19. The method of claim 17, wherein the metric is calculated according to one of the following equations:

${\mathrm{SM}}_k={\mathrm{SINR}}_k;<br><br><br><br>\mathrm{maximum}<br><br><br><br>\mathrm{SINR}<br><br><br><br>\mathrm{scheme},<br><br>{\mathrm{SM}}_k<br><br>\left(i\right)=\frac{R_k<br><br>\left(i\right)}{T_k^{\mathrm{\alpha <br><br>}}<br><br>\left(i\right)};<br><br>\mathrm{proportional}<br><br><br><br>\mathrm{fairness}<br><br><br><br>\mathrm{scheme},\text{<br><br>}<br><br>T_k<br><br>\left(i+1\right)=\{\begin{array}{c}<br><br>\mathrm{\beta <br><br>}<br><br><br><br>T_k<br><br>\left(i\right)<br><br>\text{;<br><br>}<br><br><br><br>\mathrm{non}<br><br>\text{-}<br><br>\mathrm{scheduled}<br><br><br><br>\mathrm{at}<br><br><br><br>\mathrm{time}<br><br><br><br>i\\ <br><br>\mathrm{\beta <br><br>}<br><br><br><br>T_k<br><br>\left(i\right)+\left(1-\mathrm{\beta <br><br>}\right)<br><br>R_k<br><br>\left(i\right)<br><br>\text{;<br><br>}<br><br><br><br>\mathrm{scheduled}<br><br><br><br>\mathrm{at}<br><br><br><br>\mathrm{time}<br><br><br><br>i,\end{array}$

where SM_k denotes a scheduling metric of a k^th mobile station, SINR_k denotes a signal to interference and noise ratio (SINR), T_k(i) denotes an average data rate of the k^th mobile station at a time i, α

denotes a scaling constant, and β

denotes a forgetting constant.

20. The method of claim 19, wherein the metric is calculated in an initial stage of scheduling in which the mobile stations to be scheduled are determined.

21. The method of claim 17, wherein the metric is calculated by using the scheduling metric of each mobile station according to a corresponding scheduling scheme and by using a reuse matrix (RM) representing an interference relation between the base station and a relay station (RS).

22. The method of claim 21, wherein the metric is calculated according to:

$f<br><br>\left({\mathrm{SM}}_k,\mathrm{RM}\right)={\mathrm{SM}}_k+N_{\mathrm{BS}-\mathrm{RS}}<br><br>\left(\mathrm{RM}\right)\times <br><br>\underset{j=1}{\overset{N_{\mathrm{RS}-\mathrm{pool}}}{\sum <br><br>}}<br><br>\mathrm{Avg}<br><br>\left[{\mathrm{SM}}^j\right],$

where SM_k denotes a scheduling metric of a k^th mobile station, RM denotes a reuse matrix (RM), f(•

) denotes a reuse-based scheduling metric, N_BS-RS(RM) denotes an average number of base stations or relay stations that can be additionally selected when the k^th mobile station is selected, and Avg[SM^j] denotes an average value of scheduling metrics of mobile stations dependent on a j^th relay station.

23. The method of claim 22, wherein the metric is calculated whenever each of the mobile station is selected.

24. A method of feeding back interference information of a mobile station (MS) in a multi-hop relay wireless communication system, the method comprising:

measuring a received signal level from a base station (BS) and a relay station (RS) by using a received signal;

determining a serving node and at least one interference node;

generating a control information comprising an interference node information and a received signal level information; and

transmitting the control information.