US-12621824-B2 - Method and apparatus for long term evolution operation in unlicensed and shared spectrum for cloud radio access networks

US12621824B2US 12621824 B2US12621824 B2US 12621824B2US-12621824-B2

Abstract

There is provided a system, method, and interfaces for Radio Access Networks and Cloud Radio Access Networks.

Inventors

Wessam Afifi Ahmed
Sridhar Rajagopal
Ajay Nigam
Hersh Vardhan SHUKLA
Tarak TARANEKAR
Ajit Ashok JOSHI

Assignees

MAVENIR NETWORKS, INC.

Dates

Publication Date: 20260505
Application Date: 20240103

Claims (9)

1 . A system comprising: a Baseband Unit (BBU) configured to calculate average occupancy ratios of all valid channel combinations and select a channel with a minimum occupancy ratio if a difference between two of the channels with a least average occupancy ratios is larger than a threshold, wherein the BBU is configured to calculate the channel combinations of channel f c * and channel f c ** of the valid channel combinations as ( f c * , f c ** ) = { arg ⁢ min f c ∈ A ⁢ { ( R o ( f c ⁢ 1 ) + R o ( f c ⁢ 2 ) 2 ) , ( R o ( f c ⁢ 1 ) + R o ( f c ⁢ 3 ) 2 ) , … , ( R o ( f c ⁢ 4 ) + R o ( f c ⁢ 5 ) 2 ) } , arg ⁢ min f c ∈ A ⁢ { P _ avg ( f c min , f c ′ ⁢ min ) , P _ avg ( f c min + 1 , f c ′ ⁢ min + 1 ) } , if ⁢ ( R o _ ( f c min + 1 , f c ′ ⁢ min + 1 ) - R o _ ( f c min , f c ′ ⁢ min ) ) > R o ThGap .
2 . The system of claim 1 , wherein the BBU is configured to select the channel with a minimum average RSSI from the two channels with lowest occupancy ratios when the difference between the two least average occupancy ratios is not larger than the threshold.
3 . A Baseband Unit (BBU) configured to calculate average occupancy ratios of all valid channel combinations and select a channel with a minimum occupancy ratio if a difference between two of the channels with a least average occupancy ratios is larger than a threshold, wherein a maximum number of unlicensed channels that a radio access network device is allowed to simultaneously transmit on is equal to or less than 4, and the maximum frequency separation between any two carrier center frequencies on which cellular transmissions allowed are less than or equal to 62 MHz.
4 . A method comprising: calculating, by a Baseband Unit (BBU), average occupancy ratios of all valid channel combinations; and selecting a channel with a minimum occupancy ratio if a difference between two least average occupancy ratios is larger than a threshold, wherein the method further comprises calculating, by the BBU, the channel combinations channel f c * and channel f c ** of the valid channel combinations as ( f c * , f c ** ) = { arg ⁢ min f c ∈ A ⁢ { ( R o ( f c ⁢ 1 ) + R o ( f c ⁢ 2 ) 2 ) , ( R o ( f c ⁢ 1 ) + R o ( f c ⁢ 3 ) 2 ) , … , ( R o ( f c ⁢ 4 ) + R o ( f c ⁢ 5 ) 2 ) } , arg ⁢ min f c ∈ A ⁢ { P _ avg ( f c min , f c ′ ⁢ min ) , P _ avg ( f c min + 1 , f c ′ ⁢ min + 1 ) } , if ⁢ ( R o _ ( f c min + 1 , f c ′ ⁢ min + 1 ) - R o _ ( f c min , f c ′ ⁢ min ) ) > R o ThGap .
5 . The method of claim 4 , further comprising: selecting, by the BBU, the channel with a minimum average RSSI from the two channels with lowest occupancy ratios when the difference between the two least average occupancy ratios is not larger than the threshold.
6 . A method of comprising: calculating, by a Baseband Unit (BBU), average occupancy ratios of all valid channel combinations; and selecting a channel with a minimum occupancy ratio if a difference between two least average occupancy ratios is larger than a threshold, wherein a maximum number of unlicensed channels that a radio access network device is allowed to simultaneously transmit on is equal to or less than 4, and the maximum frequency separation between any two carrier center frequencies on which transmissions allowed are less than or equal to 62 MHz.
7 . A system comprising: means for calculating average occupancy ratios of all valid channel combinations in a cell and selecting a channel with a minimum occupancy ratio if a difference between two of the channels with a least average occupancy ratios is larger than a threshold, wherein the method further comprises calculating, by the BBU, the channel combinations channel f c * and channel f c ** of the valid channel combinations as ( f c * , f c ** ) = { arg ⁢ min f c ∈ A ⁢ { ( R o ( f c ⁢ 1 ) + R o ( f c ⁢ 2 ) 2 ) , ( R o ( f c ⁢ 1 ) + R o ( f c ⁢ 3 ) 2 ) , … , ( R o ( f c ⁢ 4 ) + R o ( f c ⁢ 5 ) 2 ) } , arg ⁢ min f c ∈ A ⁢ { P _ avg ( f c min , f c ′ ⁢ min ) , P _ avg ( f c min + 1 , f c ′ ⁢ min + 1 ) } , if ⁢ ( R o _ ( f c min + 1 , f c ′ ⁢ min + 1 ) - R o _ ( f c min , f c ′ ⁢ min ) ) > R o ThGap .
8 . The system of claim 7 , the means further comprising means for calculating the channel with a minimum average RSSI from the two channels with lowest occupancy ratios when the difference between the two least average occupancy ratios is not larger than the threshold.
9 . A system comprising: means for calculating average occupancy ratios of all valid channel combinations in a cell; and selecting a channel with a minimum occupancy ratio if a difference between two of the channels with a least average occupancy ratios is larger than a threshold, wherein a maximum number of unlicensed channels that a radio access network device is allowed to simultaneously transmit on is equal to or less than 4, and the maximum frequency separation between any two carrier center frequencies on which cellular transmissions allowed are less than or equal to 62 MHz.

Description

CROSS REFERENCE TO RELATED APPLICATIONS The present application is a divisional of U.S. patent application Ser. No. 17/409,441, entitled METHOD AND APPARATUS FOR LTE OPERATION IN UNLICENSED AND SHARED SPECTRUM FOR CLOUD RADIO ACCESS NETWORKS, filed on Aug. 23, 2021, issuing on Jan. 9, 2024 as U.S. Pat. No. 11,871,402; which is a divisional of U.S. patent application Ser. No. 16/272,255, entitled METHOD AND APPARATUS FOR LTE OPERATION IN UNLICENSED AND SHARED SPECTRUM FOR CLOUD RADIO ACCESS NETWORKS, filed on Feb. 11, 2019 and issued on Dec. 28, 2021 as U.S. Pat. No. 11,212,818, which claims the benefit of: U.S. Provisional Patent Application No. 62/628,538, entitled METHOD AND APPARATUS FOR LTE OPERATION IN UNLICENSED AND SHARED SPECTRUM FOR CLOUD RADIO ACCESS NETWORKS, filed on Feb. 9, 2018; U.S. Provisional Patent Application No. 62/659,546, entitled METHOD AND APPARATUS FOR LTE OPERATION IN UNLICENSED AND SHARED SPECTRUM FOR CLOUD RADIO ACCESS NETWORKS, filed on Apr. 18, 2018; and U.S. Provisional Patent Application No. 62/668,012, entitled METHOD AND APPARATUS FOR LICENSED-ASSISTED ACCESS (LAA) FOR CLOUD RAN AND FOR MULTI-LAA CELLS, filed on May 7, 2018. Each of these patent applications and patents are incorporated herein by reference. BACKGROUND OF THE DISCLOSURE 1. Field of the Disclosure The present disclosure relates to systems and methods for radio access networks. 2. Description of the Related Art Conventional the radio access networks (RAN) were built employing an integrated unit where the entire RAN was processed. The RAN network traditionally uses application specific hardware for processing, making them difficult to upgrade and evolve. As future networks evolve to have massive densification of networks to support increased capacity requirements, there is a growing need to reduce the capital and operating costs of RAN deployment and make the solution scalable and easy to upgrade. Cloud based Radio Access Networks (C-RAN) are networks where a significant portion of the RAN layer processing is performed at a central unit (CU), also known as the baseband unit (BBU), located in the cloud on commercial off the shelf servers while the RF and real-time critical functions can be processed in the remote radio unit (RRU) or distributed unit (DU). Traditional RANs implement the protocol stack (e.g., Physical Layer (PHY), Medium Access Control (MAC), Radio Link Control (RLC), Packet Data Convergence Control (PDCP layers)) at the base-station (also referred to as the eNodeB or eNB). In Cloud RAN, different radio functions are split between the RRU and the baseband unit BBU. RRUs are implemented locally onsite, while the BBU is virtualized on the cloud, which could be hundreds of miles away from the RRU. A single BBU (or vRAN) can control multiples of RRUs in different locations. Cloud RAN provides centralization and virtualization of RAN networks, leading to benefits such as (a) operation cost reduction due to resource pooling and running the network on general-purpose hardware, enabling economies of scale, (b) performance improvements due to better interference management, (c) remote upgradeability and management of the network, and (d) simpler migration to add new features and transition from 4G to 5G networks. In conventional long-term evolution (LTE) operation in licensed bands, mobile network operators have exclusive right to use the spectrum. Hence, they have full control over scheduling, resource allocation, and spectrum access. As new wireless technologies evolve, and since wireless demand has increased exponentially in the last decade, there has been an interest in the last few years in extending LTE technologies to operate in unlicensed and shared spectrum. This happened especially after the FCC has opened new bands for unlicensed/shared operation in the 5 GHz UNII bands and other bands. SUMMARY OF THE DISCLOSURE The present disclosure provides embodiments of a system, method, and devices for LTE operation in the unlicensed bands, where a BBU is configured to schedule non-Guaranteed Bit Rate (non-GBR) traffic on unlicensed cells and Guaranteed Bit Rate (GBR) traffic on licensed cells. The BBU is also configured to schedule priority classes 3 and 4 on unlicensed cells, while priority classes 1 and 2 are scheduled on licensed cells. The present disclosure also provides embodiments of a system and method for LTE operation in the unlicensed bands in the cloud RAN framework, where a BBU, at the Radio Link Control (RLC) layer, is configured to retransmit failed packets originally transmitted on the unlicensed band on a licensed band. The present disclosure further provides embodiments of a system and method wherein a BBU is configured to set a timer, based on an end-to-end latency requirement of the traffic, and tries transmission on an unlicensed band. Once the timer expires, the BBU can be configured to retransmit the failed packets on licensed bands. The timer threshold can be set based on the expec