Semi-decentralized scheduling in a wireless network

Patent metadata

Field	Value
Publication number	US-9648624-B2
Application number	US-201314415622-A
Country	US
Kind code	B2
Filing date	Jul 16, 2013
Priority date	Jul 20, 2012
Publication date	May 9, 2017
Grant date	May 9, 2017

Abstract

In a network ( 700, 800 ) with a plurality of cells ( 715, 815, 825 ), there may be interference couplings among the cells ( 715, 815, 825 ). This may be particularly true for heterogeneous networks ( 800 ). For radio resource scheduling in such network ( 700, 800 ), a semi-decentralized scheduling is proposed in which radio resource scheduling issue is reformulated as load scheduling issue. In the proposed semi-decentralized scheduling, portions of the total load or available headroom are centrally allocated to each local node ( 710, 810, 820 ) subject to the stability of the network ( 700, 800 ). At each local node ( 710, 810, 820 ), radio resources are granted to users ( 740, 840 ) of that local node ( 710, 810, 820 ) subject to the portion of the load or headroom allocated to that local node ( 710, 810, 820 ).

First claim

What is claimed is:

1. A method performed at a central scheduler to schedule radio resources to users located in a plurality of cells of a wireless network, the method comprising:
for each cell, obtaining load related parameters of that cell;
for each cell pair among the plurality of cells, obtaining a coupling factor of that cell pair;
for each cell, allocating a free headroom L Fj to that cell based on the load related parameters of the cells and based on the coupling factors among the cells; and
for each cell, notifying a local scheduler associated with that cell of the free headroom L Fj allocated to that cell;
wherein each cell:
a) partially or wholly overlaps with at least one other cell, or
b) is geographically adjacent to at least one other cell, or
c) partially or wholly overlaps with at least one other cell and is geographically adjacent to the at least one other cell,

wherein for each cell, the load related parameters of that cell comprise a minimum required load Σ i=1 n j L jil , a throughput distribution Σ i=1 n j r ji , and a throughput proportionality {circumflex over (k)} j of that cell,
wherein each cell pair comprises a cell x and a cell y, and the corresponding coupling factor u xy couples an interference experienced at the cell x due to usage of the radio resources scheduled for the users of the cell y,
wherein for each cell, the corresponding free headroom L Fj defines an amount of load headroom available for distribution among the users of that cell when the local scheduler associated with that cell schedules the radio resources to those users, and
wherein the free headrooms L Fj are allocated subject to a system stability of the wireless network, the system stability being defined such that when the radio resources are scheduled to the users in accordance with the allocated headrooms L Fj , then for each cell, an interference experienced at that cell due to usage of the scheduled radio resources does not exceed a maximum allowable interference at that cell.

2. The method of claim 1 , wherein the step of obtaining the load related parameters for each cell comprises:
for each cell, receiving the throughput distribution Σ i=1 n j r ji of that cell from the local scheduler associated with that cell;
for each cell, receiving the throughput proportionality {circumflex over (k)} j of that cell from the local scheduler associated with that cell; and

for each cell, determining the minimum required load Σ i=1 n j L jil of that cell.

3. The method of claim 1 , wherein the step of allocating the free headrooms L Fj to the plurality of cells comprises:
generating a set of simultaneous equations, each equation modeling a total received power I tot x at a radio node of each cell x; and
solving the set of simultaneous equations for the free headrooms L Fj to be allocated to the plurality of cells,
wherein for each cell, the total received power I tot x at the radio node of that cell is modeled as a combination of an own contribution, a coupled interference contribution, and an other contribution,
wherein the own contribution of the cell x comprises contribution to the total received power I tot x due to transmissions from the users of the cell x, and
wherein the coupled interference contribution to the cell x comprises, for each cell y different from the cell x, an own contribution of that different cell y coupled to the cell x by the coupling factor u xy .

4. The method of claim 3 ,
wherein the step of generating the set of simultaneous equations comprises generating a matrix in a form of AD L in which

A
=

[

1

u
12

…

u

1
⁢
c

u
21

1

…

u

2
⁢
c

⋮

⋮

⋱

⋮

u

c
⁢

⁢
1

u

c
⁢

⁢
2

…

1

]

 is a coupling matrix, each u xy is the coupling factor that couples interferences in cell x to users in cell y, c is the number of cells,
D L =diag(L), L=[L HR1 ,L HR2 , . . . , L HRc ] T , and each L HRy is the total load of the cell y, and

wherein the step of solving the set of simultaneous equations comprises solving the matrix AD L for a free headroom matrix

L
F

=

[

L

F
⁢

⁢
1

L

F
⁢

⁢
2

⋮

Assignees

• Telefonaktiebolaget L M Erisccon (publ)
• Lundin Leif
• ERICSSON TELEFON AB L M (publ)

Inventors

• Geijer Lundin Erik
• Goodwin Graham C
• Lau Katrina

Classifications

• H04W72/52 Primary

  based on load · CPC title

• H04W72/541

  using the level of interference · CPC title

• H04W28/16

  Central resource management; Negotiation of resources or communication parameters, e.g. negotiating bandwidth or QoS [Quality of Service] · CPC title

• H04W16/08

  Load shedding arrangements · CPC title

• H04W84/045

  using private Base Stations, e.g. femto Base Stations, home Node B · CPC title