Packet scheduler in a radio system
The invention relates to scheduling of data packets in a radio transmitter. A scheduling metric is applied in the scheduling, which scheduling metric may be dynamically adjusted during transmission of data packets to the receivers.
1 . A data packet scheduler for a radio system, comprising:
means for scheduling, by applying a scheduling metric, data packets to be delivered in radio connections within a radio cell in future transmission time intervals; and
means for adjusting fairness of the scheduling metric dynamically by adjusting a fairness parameter during delivery of the data packets.
2 . A data packet scheduler according to claim 1 , wherein the adjusting means is configured to adjust the fairness parameter such that the scheduling metric converges towards a maximum committed information rate scheduling when less fairness between users of the radio connections is wanted.
3 . A data packet scheduler according to claim 2 , wherein in the maximum committed information rate scheduling, the users of the radio connections are sorted into a descending order based on a bit rate that is, due to radio environments of the users, delivered in the radio connections of the users.
4 . A data packet scheduler according to claim 1 , wherein the adjusting means is configured to adjust the fairness parameter such that the scheduling metric converges towards an equal throughput scheduling when more fairness between users of the radio connections is wanted.
5 . A data packet scheduler according to claim 4 , wherein, in the equal throughput scheduling, data transmissions to the users of the radio connections are scheduled such that an average throughput with respect to each user is equal.
6 . A data packet scheduler according to claim 1 , wherein the adjustment means is configured to adjust the scheduling metric between unfair scheduling and fair scheduling, and in the unfair scheduling a user having best radio environment is scheduled first, and in the fair scheduling, equal throughput of the data packets is ensured to all of the users.
7 . A data packet scheduler according to claim 1 , wherein the adjustment means is configured to change the fairness parameter on the basis of a cell load.
8 . A data packet scheduler according to claim 7 , wherein the adjustment means is configured to decrease fairness in the radio cell when the cell load is high.
9 . A data packet scheduler according to claim 7 , wherein the adjustment means is configured to increase fairness in the radio cell when the cell load is low.
10 . A data packet scheduler according to claim 7 , wherein the cell load is determined on the basis of a number of users in the radio cell.
11 . A data packet scheduler according to claim 1 , wherein the adjustment means provides a user interface for setting the fairness parameter by an operator.
12 . A data packet scheduler according to claim 1 , wherein the scheduling metric M is
M
=
S
(
k
)
f
R
(
k
)
,
wherein
S(k) is a bit rate that is, due to the radio environment of the user, delivered in a radio connection of the user in a future transmission time interval k;
f is the fairness parameter;
R(k) is an average throughput bit rate of the user in at least two transmission time intervals k.
13 . A data packet scheduler according to claim 12 , wherein the adjustment means is configured to set the fairness parameter to one (1) when a proportional fair scheduling is wanted.
14 . A data packet scheduler according to claim 12 , wherein the adjustment means is configured to set the fairness parameter to a large value to converge the scheduling metric towards a maximum committed information rate scheduling.
15 . A data packet scheduler according to claim 12 , wherein the adjustment means is configured to set the fairness parameter to zero (0) when an equal throughput scheduling is wanted.
16 . A radio transmitter, comprising:
a data packet scheduler comprising
means for scheduling, by applying a scheduling metric, data packets to be delivered in radio connections within a radio cell in future transmission time intervals, and
means for adjusting fairness of the scheduling metric dynamically by adjusting a fairness parameter during delivery of the data packets.
17 . A radio receiver, comprising
a data packet scheduler
means for scheduling, by applying a scheduling metric, data packets to be delivered in radio connections within a radio cell in future transmission time intervals, and
means for adjusting fairness of the scheduling metric dynamically by adjusting a fairness parameter during delivery of the data packets.
18 . A method of scheduling data packets in a radio system, comprising:
scheduling data packets, by applying a scheduling metric, to be delivered in radio connections within a radio cell in future transmission time intervals; and
adjusting fairness of the scheduling metric dynamically during delivery of the data packets in the radio connections.
19 . A method according to claim 18 , further comprising:
adjusting the scheduling metric between unfair scheduling and fair scheduling;
scheduling first a user of a radio connection having best radio environment in the unfair scheduling; and
ensuring an equal throughput of the data packets to all of the users of the radio connections in the fair scheduling.
20 . A method according to claim 18 , further comprising:
adjusting the fairness parameter on the basis of a cell load.
21 . A method according to claim 18 , further comprising:
decreasing the fairness in the radio cell when a cell load is high.
22 . A method according to claim 18 , further comprising:
increasing the fairness in the radio cell when a cell load is low.
23 . A method according to claim 18 , further comprising:
determining the cell load on the basis of a number of users in the radio cell.
24 . A method according to claim 18 , wherein the scheduling metric M is
M
=
S
(
k
)
f
R
(
k
)
,
wherein
S(k) is a bit rate that is, due to the radio environment of a user of a radio connection, delivered in a future transmission time interval k;
f is the fairness parameter;
R(k) is an average throughput bit rate of a radio connection in at least two transmission time intervals k.
25 . A computer program embodied on a computer readable medium, the computer program being configured to schedule data packets in radio connections within a radio cell, the computer program being configured to perform the steps of:
scheduling data packets to be delivered in radio connections in future transmission time intervals, by applying a scheduling metric; and
adjusting fairness of the scheduling metric dynamically during delivery of the data packets in the radio connections.
26 . A computer program distribution medium readable by a computer and encoding a computer program of instructions configured to schedule data packets in radio connections within a radio cell and configured to perform the steps of:
scheduling data packets, by applying a scheduling metric, to be delivered in future transmission time intervals, and
adjusting fairness of the scheduling metric dynamically during delivery of the data packets.