System and method for joint scheduling in dual-carrier wireless backhaul networks

• US 9,544,792 B2
• Filed: 06/25/2014
• Issued: 01/10/2017
• Est. Priority Date: 09/13/2010
• Status: Active Grant

• Current Assignee: BLiNQ Networks, Inc. (Communication Components, Inc.)
• Original Assignee: BLiNQ Wireless Inc.
• Inventors: Cheng, Ho Ting, Moraru, Alexandru, Bin Sediq, Akram, Selea, Radu Bogdan
• Primary Examiner(s): KHAJURIA, SHRIPAL K
• Application Number:
  US14/314,878
• Publication Number:
  US 20150382347A1
• Time in Patent Office: 930 Days
• Field of Search: 370/254, 370/329
• US Class Current: 1/1
• CPC Class Codes: H04W 24/08 Testing, supervising or monitoring using real traffic
• CPC Class Codes: H04W 48/16 Discovering, processing access restriction or access information
• CPC Class Codes: H04W 72/0446 Resources in time domain, e.g. slots or frames
• CPC Class Codes: H04W 72/0453 Resources in frequency domain, e.g. a carrier in FDMA
• CPC Class Codes: H04W 72/542 using measured or perceived quality

Abstract

A system and method for joint scheduling in a dual-carrier fixed wireless backhaul network is disclosed, wherein the primary carrier is a licensed band, and the secondary carrier is an unlicensed or lower cost shared carrier. The network comprises a plurality of Hub modules, each serving a cluster of one or more Remote backhaul modules (RBMs). A special frame structure and a control channel on the primary carrier carries control signalling messages for RBMs assigned to either the primary or secondary carrier. RBMs with a performance metric, such a spectral efficiency, above a threshold are assigned to the primary carrier. Other RBMs are assigned the secondary carrier, and a channel assignment is then performed. A transmission mode is determined based on instantaneous channel conditions, to optimize overall system performance across a network neighborhood and meet RBM quality of service requirements. A centralized server/processing unit coordinates dual carrier joint scheduling functions.

Claims

1. A method of joint scheduling in a dual-carrier fixed wireless backhaul network operating with a primary carrier and a secondary carrier, the wireless backhaul network comprising a plurality of nodes comprising a plurality of Hub modules, each Hub module serving one or more remote backhaul modules (RBMs) through Hub-RBM radio links, wherein the method comprises:

for Hub modules (Hubs) and RBMs configured for dual-carrier operation using the primary carrier and the secondary carrier, and wherein the primary carrier is a licensed band and the secondary carrier is a lower cost shared band or an unlicensed band, providing a frame structure wherein control signaling messages are carried on the primary carrier;

performing network entry for each said RBM on the primary carrier; and

performing carrier assignment wherein each Hub transmits a broadcast frame on the primary carrier assigning each served RBM to the primary carrier or the secondary carrier; and

wherein performing network entry further comprises;

performing Hub-RBM clustering comprising associating each RBM to a respective serving Hub; and

for Hubs and/or RBMs having one or more beams, performing Hub-beam selection and RBM-beam selection for each Hub-RBM radio link;

obtaining initial performance metrics, including pathloss information, for Hub-RBM radio links between each RBM and its respective serving Hub using the primary carrier, and storing said performance metrics for each Hub-RBM link in a centralized processing unit;

and

wherein performing carrier assignment further comprises;

for Hub-RBM links for each Hub and respective served RBMs of at least part of the network (neighborhood);

a) obtaining a performance metric and computing a utility gain for each of a plurality of time slot assignments on the primary carrier;

b) obtaining a performance metric and computing a utility gain for each of a plurality of time slot assignments on the secondary carrier and for each channel of the secondary carrier;

c) storing in the centralized processing unit, tables or maps of utility gain values from steps a) and b) and computing therefrom a maximum achievable sum utility over the neighborhood;

d) selecting for each RBM

a time slot of the primary carrier;

or

a time slot of the secondary carrier;

to optimize the sum utility over the neighborhood;

e) scheduling each RBM to the selected carrier and time slot; and

f) for each Hub-RBM radio link, selecting a transmission mode and a Modulation and Coding Scheme (MCS) based on instantaneous channel conditions and to meet an RBM quality of service requirement.

2. The method of claim 1, wherein the secondary carrier is an unlicensed band comprising a plurality of channels, and wherein the control signaling messages for RBMs assigned to the secondary carrier comprise a channel assignment and a fallback channel assignment.

3. The method of claim 1, wherein joint scheduling is coordinated by a centralized processing unit that communicates with each Hub and wherein performance metrics, carrier assignments and slot assignments are communicated between RBMs and their serving Hubs using said control signaling on the primary carrier.

4. The method of claim 1, wherein performance metrics, carrier assignments and slot assignments are stored for look-up in a centralized server.

5. The method of claim 1, comprising generating a first RBM map for RBMs assigned to the primary carrier and generating a second RBM map for RBMs assigned to the secondary carrier, said second RBM map further comprising RBM channel assignments for each RBM.

6. The method of claim 1, wherein obtaining performance metrics comprises performing Radio Frequency Environment Characteristics (RFEC) measurements to generate an RFEC interference map comprising performance metrics for each Hub-RBM radio link, and wherein:

RBMs having a performance metric above a performance threshold are assigned to slots on the primary carrier;

other RBMS are assigned to the secondary carrier; and

then the RBMS assigned to the secondary carrier are given a channel assignment based on channel availability and/or performance metrics from a RFEC interference map.

7. The method of claim 1, wherein the sum utility is optimized for a set of Hub-RBM links of a neighborhood comprising:

a Hub (sector);

or

a site comprising a plurality of co-located Hubs;

or

across multiple sites of the network;

or

over the entire network.

8. The method of claim 1, performed for each sector on a neighborhood basis, wherein:

in step a) each Hub computes predicted CINRs for each RBM served by the Hub for each time slot for the primary carrier;

in step b) each Hub computes predicted CINRs for each RBM served by the Hub for each time slot for the secondary carrier, for each channel; and

then each Hub assigns to each served RBM a time slot on the primary carrier or secondary carrier such that the sum utility is maximized over the neighborhood.

9. The method of claim 8, wherein the neighborhood is one of:

a single Hub;

a set of co-located Hubs;

Hubs of a plurality of sites; and

all Hubs in the network.

10. The method of claim 1, wherein the RBMs comprise multi-mode RBMs, and further comprising performing RBM reception mode selection wherein each RBM reports to its serving Hub, one or more of:

a pathloss PL for each RBM-beam using the primary and secondary carriers;

RSSIs measured for each time slot on the primary and secondary carriers; and

a reception mode and corresponding reception mode gains.

11. The method of claim 1, wherein the channel assignment includes a primary channel and a fall back channel.

12. The method of claim 1, wherein the performance metric for each RBM comprises one of:

a spectral efficiency on the primary carrier;

a channel gain with respect to its serving Hub greater than a threshold;

a channel gain with respect to one or more interfering Hubs greater than a threshold; and

a Quality of Service (QoS) satisfaction indicator, including throughput and delay requirements.

13. The method of claim 1, wherein assigning each RBM to the selected carrier and time slot to optimize the sum utility over the set of Hubs comprises control channel signaling on the primary carrier.

14. A system for joint scheduling in a dual-carrier fixed wireless backhaul network comprising a plurality of nodes, wherein each node comprises a plurality of Hub modules, each Hub module serving one or more Remote Backhaul Modules (RBMs) through Hub-RBM radio links, at least some of said Hub modules and RBMs being configured for dual-carrier operation with a primary carrier and a secondary carrier, wherein the primary carrier is a licensed band and the secondary carrier is a lower cost shared band or an unlicensed band, and the system further comprising a centralized server or centralized processing unit for coordinating Dual Carrier Joint Scheduling (DCJS) across the network using a primary carrier and a secondary carrier, and wherein the centralized server or centralized processing unit is configured for implementing joint scheduling comprising the steps of:

for Hub modules (Hubs) and RBMs configured for dual-carrier operation using the primary carrier and the secondary carrier, and wherein the primary carrier is a licensed band and the secondary carrier is a lower cost shared band or an unlicensed band, providing a frame structure wherein control signaling messages are carried on the primary carrier;

performing network entry for each said RBM on the primary carrier; and

performing carrier assignment wherein each Hub transmits a broadcast frame on the primary carrier assigning each served RBM to the primary carrier or the secondary carrier; and

wherein performing network entry further comprises;

performing Hub-RBM clustering comprising associating each RBM to a respective serving Hub; and

for Hubs and/or RBMs having one or more beams, performing Hub-beam selection and RBM-beam selection for each Hub-RBM radio link;

obtaining initial performance metrics, including pathloss information, for Hub-RBM radio links between each RBM and its respective serving Hub using the primary carrier, and storing said performance metrics for each Hub-RBM link in a centralized processing unit;

and

wherein performing carrier assignment further comprises;

for Hub-RBM links for each Hub and respective served RBMs of at least part of the network (neighborhood);

a) obtaining a performance metric and computing a utility gain for each of a plurality of time slot assignments on the primary carrier;

b) obtaining a performance metric and computing a utility gain for each of a plurality of time slot assignments on the secondary carrier and for each channel of the secondary carrier;

c) storing in the centralized processing unit, tables or maps of utility gain values from steps a) and b) and computing therefrom a maximum achievable sum utility over the neighborhood;

d) selecting for each RBM

a time slot of the primary carrier;

or

a time slot of the secondary carrier;

to optimize the sum utility over the neighborhood;

e) scheduling each RBM to the selected carrier and time slot; and

f) for each Hub-RBM radio link, selecting a transmission mode and a Modulation and Coding Scheme (MCS) based on instantaneous channel conditions and to meet an RBM quality of service requirement.

15. The system of claim 14, wherein the centralized server or processing unit provides for DJCS to be implemented across the entire network, across a neighborhood comprising a plurality of sites, on a per site basis for a plurality of co-located Hubs, or on a per sector basis.

16. The system of claim 14, wherein, when DCJS is carried out for a small neighbourhood comprising a single site or a single sector, a processing unit of each respective Hub performs measurements of metrics, communicates performance metrics and other data to the centralized server to storage and look-up and optionally shares data directly with other Hubs of the site.

17. The system of claim 14, wherein the centralized server stores performance metrics for each Hub-RBM radio link for look-up and coordinates obtaining performance metrics for each Hub-RBM radio link, by performing RFEC measurements.

18. The system of claim 14, wherein the centralized server coordinates:

a) obtaining a performance metric and computing a utility gain for each of a plurality of time slot assignments on the primary carrier;

b) obtaining a performance metric and computing a utility gain for each of a plurality of time slot assignments on the secondary carrier;

and the centralized server stores, tables or maps of utility gain values from steps a) and b) and computes therefrom a maximum achievable sum utility over the neighborhood.

19. The system of claim 14 wherein the centralized server is configured to coordinate implementation of joint DCJS by one or more of:

per sector DCJS with fixed Hub-beam and channel assignments;

per site DCJS with fixed Hub-beam and channel assignments;

per neighborhood and per network DCJS with fixed beam and channel assignments;

per sector, per site, per neighborhood or per network DJCS with Hub-beam selection and channel selection.

20. The system of claim 14 wherein the centralized server coordinates interference detection and sensing, coordination and implementation of carrier assignment, channel assignment, and resource assignment, which optionally includes zone coordination or slot assignment.

21. A non-transitory computer readable storage medium in a dual-carrier fixed wireless backhaul network comprising a plurality of nodes comprising a plurality of Hub modules, each Hub module serving one or more remote backhaul modules (RBMs) through Hub-RBM radio links, at least some of said Hub modules and RBMs being configured for dual-carrier operation on a primary carrier and a secondary carrier, wherein the primary carrier is a licensed band, and the secondary carrier is a lower cost shared band or an unlicensed band, and said computer readable storage medium being centralized or distributed and storing instructions, which when executed in one or more processing units of the backhaul network, implement dual carrier joint scheduling comprising the steps of:

for Hub modules (Hubs) and RBMs configured for dual-carrier operation using the primary carrier and the secondary carrier, and wherein the primary carrier is a licensed band and the secondary carrier is a lower cost shared band or an unlicensed band, providing a frame structure wherein control signaling messages are carried on the primary carrier;

performing network entry for each said RBM on the primary carrier; and

performing carrier assignment wherein each Hub transmits a broadcast frame on the primary carrier assigning each served RBM to the primary carrier or the secondary carrier; and

wherein performing network entry further comprises;

performing Hub-RBM clustering comprising associating each RBM to a respective serving Hub; and

for Hubs and/or RBMs having one or more beams, performing Hub-beam selection and RBM-beam selection for each Hub-RBM radio link;

obtaining initial performance metrics, including pathloss information, for Hub-RBM radio links between each RBM and its respective serving Hub using the primary carrier, and storing said performance metrics for each Hub-RBM link in a centralized processing unit;

and

wherein performing carrier assignment further comprises;

for Hub-RBM links for each Hub and respective served RBMs of at least part of the network (neighborhood);

a) obtaining a performance metric and computing a utility gain for each of a plurality of time slot assignments on the primary carrier;

b) obtaining a performance metric and computing a utility gain for each of a plurality of time slot assignments on the secondary carrier and for each channel of the secondary carrier;

c) storing in the centralized processing unit, tables or maps of utility gain values from steps a) and b) and computing therefrom a maximum achievable sum utility over the neighborhood;

d) selecting for each RBM

a time slot of the primary carrier;

or

a time slot of the secondary carrier;

to optimize the sum utility over the neighborhood;

e) scheduling each RBM to the selected carrier and time slot; and

f) for each Hub-RBM radio link, selecting a transmission mode and a Modulation and Coding Scheme (MCS) based on instantaneous channel conditions and to meet an RBM quality of service requirement.

22. A method of joint scheduling in a dual-carrier fixed wireless backhaul network comprising a plurality of nodes, each node comprising a plurality of Hub modules, each Hub module serving one or more remote backhaul modules (RBMs) through Hub-RBM radio links and operating with a primary carrier and a secondary carrier, the primary carrier being a licensed band and the secondary carrier being a lower cost shared band or an unlicensed band, wherein the method comprises:

in an initialization phase;

performing Hub-RBM clustering comprising associating each RBM to a respective serving Hub; and

for Hubs and/or RBMs having one or more beams, performing Hub-beam selection and RBM-beam selection for each Hub-RBM radio link;

obtaining initial performance metrics, including pathloss information, for Hub-RBM radio links between each RBM and its respective serving Hub using the primary carrier, and storing said performance metrics for each Hub-RBM link in a centralized processing unit;

in a data collection phase;

for Hub-RBM links for each Hub and respective served RBMs of at least part of the network (neighborhood);

a) obtaining a performance metric and computing a utility gain for each of a plurality of time slot assignments on the primary carrier;

b) obtaining a performance metric and computing a utility gain for each of a plurality of time slot assignments on the secondary carrier and for each channel of the secondary carrier;

in a parameter selection phase;

c) storing in the centralized processing unit, tables of utility gain values from steps a) and b) and computing therefrom a maximum achievable sum utility over the neighborhood;

d) selecting for each RBM

a time slot of the primary carrier;

or

a time slot of the secondary carrier;

to optimize the sum utility over the neighborhood;

in a parameter application phase;

e) scheduling each RBM to the selected carrier and time slot; and

f) for each Hub-RBM radio link, selecting a transmission mode and a Modulation and Coding Scheme (MCS) based on instantaneous channel conditions and to meet an RBM quality of service requirement.