Interference-reducing method of forward link scheduling for wireless networks

• US 20070047569A1
• Filed: 08/23/2005
• Published: 03/01/2007
• Est. Priority Date: 08/23/2005
• Status: Active Grant

• Current Assignee: Alcatel-Lucent USA, Inc. (Nokia Corporation)
• Original Assignee: Alcatel-Lucent USA, Inc. (Nokia Corporation)
• Inventors: Viswanathan, Harish, Das, Suman
• Granted Patent: US 7,738,422 B2
• Time in Patent Office: Days
• US Class Current: 370/443
• CPC Class Codes: H04L 47/10 Flow control; Congestion control
• CPC Class Codes: H04W 16/24 Cell structures
• CPC Class Codes: H04W 52/281 taking into account user or data type priority
• CPC Class Codes: H04W 72/56 based on priority criteria
• CPC Class Codes: H04W 72/563 of the wireless resources

Abstract

A method of scheduling and sub-channelization is provided for a wireless network such as an OFDMA network. Distributed coordination is applied across sectors, such neighboring sectors will tend to schedule cell-edge users at the same time, while sub-channelizing to different portions of the full frequency band available for forward link transmissions. This tendency is achieved by dividing each sector'"'"'s users into user classes which depend upon forward link channel quality. Each user class is assigned a different set of priorities for use of available timeslots and subcarriers.

Claims

1. A method of scheduling users in a reception area of a wireless communication network to receive transmissions from a base station during a sequence of timeslots, comprising:

(a) assigning, to each of at least some users in the reception area, a different slot priority for each timeslot in the sequence, wherein the slot priorities are based at least in part on indications of channel quality such that users having channels of similar quality tend to have their respective highest slot priorities fall in the same timeslot;

(b) assigning to each of at least some said users a scheduling priority for each said timeslot, wherein each scheduling priority is based in part on the corresponding slot priority and is based in part on a fairness criterion; and

(c) scheduling a user in each said timeslot according to the scheduling priorities of the respective users for that timeslot;

wherein the reception area is one of a group of mutually neighboring reception areas belonging to distinct frequency reuse groups, and the slot priorities are assigned in the same way in all reception areas that belong to said neighbor group.

2. The method of claim 1, further comprising assigning transmission frequencies to each scheduled user, wherein:

each reuse group is allocated a distinct set of frequencies; and

the scheduled users are assigned transmission frequencies according to a priority ordering in which frequencies allocated to their own reuse group take precedence.

3. The method of claim 2, wherein transmission frequencies allocated to other reuse groups are assigned preferentially to users having relatively high channel quality.

4. The method of claim 2, carried out so as to schedule a primary user in each timeslot of said timeslot sequence, and further comprising:

scheduling at least one secondary user in at least one timeslot of said timeslot sequence and assigning to the secondary user at least some transmission frequencies allocated to other reuse groups for transmission thereon at a lower power than used for transmission to the primary user.

5. The method of claim 4, wherein the scheduling of secondary users is carried out preferentially for users having relatively high channel quality.

6. The method of claim 1, wherein the scheduling priorities are based in part on a proportional fair scheduling weight.

7. The method of claim 1, wherein the scheduling priorities are based in part on a token queue based equal throughput scheduling weight.

8. The method of claim 1, carried out with respect to a first frequency band so as to schedule at least one user in each said timeslot for transmission thereto in said first frequency band, and further carried out with respect to one or more additional frequency bands so as to schedule at least one further user in each said timeslot for transmission thereto in each of said one or more additional frequency bands.

9. The method of claim 1, wherein users having relatively poor channel quality are preferentially scheduled for timeslots in which at least one other reception area belonging to the neighbor group is preferentially scheduling empty timeslots.

10. The method of claim 9, wherein said at least one other reception area is scheduling empty timeslots according to a set of priorities for leaving slots empty.