4G Onyx Platform - Mesh Node

Introduction

This document introduces the concepts and criteria for designing a Private Cellular Network using the GXC Mesh Node in both outdoor and indoor scenarios. Figure Sample GXC Private Cellular Network serves as a reference throughout the document, providing a high-level understanding of the hardware and operational characteristics of the GXC Onyx Platform.

Sample GXC Private Cellular Network

ONYX Edge ① is a hardware appliance that houses an on-premises 4G/5G mobile core network solution. Its function is to manage:

• radio registrations
• user network entry authorizations
• enforcement of network services and policies
• configurations through the Onyx Portal
• backhauling of user traffic to the Internet

Two Indoor APs ③ are directly cabled via Ethernet to the Onyx Edge and provide indoor coverage to UE operating on CBRS bands.

The Outdoor Onyx Gateway Node ② is a High Power AP Radio (transmitting at F_gw) that not only provides access to UE within range of its RF footprint but also allows the wireless extension of the Onyx Private Wireless Network using the Mesh Node ④.

To provide subscriber access, the Mesh Node is directly cabled to an Outdoor High Powered Access Point (HP AP) ⑤ (also referred to as the Mesh AP). This access point is configured for a different frequency (F_map) from the gateway, creating a new cell for subscriber devices.

Mesh Node Implementation and Applications

Purpose and Requirements

Mesh Nodes can be placed anywhere within range of the Gateway AP, performing best with a line-of-sight backhaul connection. The following general design rules apply to network design using a Mesh node:

• The Mesh Node AP must achieve timing synchronization through one of the following options:

  • GPS (GNSS)
  • Network Synchronization (Network Listening)

    • This method requires a second backhaul antenna attached to the Mesh AP receiving an RSRP of ≥ -70 dBm. Contact GXC for design/configuration details.
• Antenna Isolation between backhaul and access antennas must be ≥ 50 dB. This is generally achieved through the selection of directional access and backhaul antennas, with narrow vertical beamwidth.

  • As a general rule, avoid positioning Mesh Node antennas within 20m of large reflective obstacles, such as a building wall, etc.
• The Mesh AP should expand coverage radially away from the Gateway AP.

  • Optimally, access and backhaul antennas should be oriented 180 degrees opposite from one another at the Mesh Node location, such that the new Mesh AP cell extends outward from the Gateway cell.
• Target backhaul signal strength range, as determined from propagation simulations, or read directly from the Mesh Node Local Control Interface (LCI).

  • For Mesh Node Peak Performance: DL RSRP > -85 dBm
  • For Mesh Node Stable cell-edge performance: DL RSRP > -100dBm

Installation of the Mesh Node

For those familiar with the Onyx platform, refer to the Mesh Node Quick Start Guide. If you would like more detailed information, refer to the Onyx GM01 Mesh Node Installation Guide or Onyx GM02 Mesh Node Installation Guide.

Standard Application

The primary use case for a Mesh Node is in an outdoor environment, where the availability of wired data backhaul is otherwise prohibitive. In this application, the only external cabling requirement is a source of power. Figure Outdoor Implementation of a Mesh Node is a graphical representation and requirements for an outdoor Mesh Node deployment.

Outdoor Implementation of a Mesh Node

Use of Multiple Mesh Nodes

Mesh Nodes are primarily used for coverage extension and with UE share the available bandwidth of the Gateway AP. It is important to note that a Mesh Node does not increase the capacity of the Gateway AP.

Figure Sample GXC Private Cellular Network is an example of the Mesh Nodes used in a currently supported star configuration. Mesh Nodes in a cascaded configuration (a Mesh Node connected to another Mesh Node) is a planned feature, contact GXC for release timing and details.

Dual Carrier/Carrier Aggregation

GM01 Mesh Node

• The Mesh Node supports 2CA in the downlink only.
• If the GW AP is configured for Dual Carrier, the Mesh Node will connect to one of the two carriers.

Mesh AP

The Mesh AP currently does not support Dual Carrier or Carrier Aggregation.

Mesh Filter and Channel Frequency Assignments

Mesh Node to Gateway Frequency Planning

A Mesh Node uses a filter network to isolate the Mesh AP’s TX/RX frequency from the Mesh Node backhaul TX/RX frequency.

During the configuration of the SAS parameters in the Onyx Portal, the operator will configure the Gateway AP and Mesh AP for a series of Preferred Frequencies (from most to least). The operator should take into consideration the desired bandwidth of 10 or 20 MHz to avoid selecting a frequency that will fall out of the “low or high” pass band ranges shown in Table Backhaul to Mesh Node-AP Frequency Assignments. This process allows for SAS grant flexibility, as channel assignments can change.

NOTE: Table Backhaul to Mesh Node-AP Frequency Assignments specifies the Backhaul (Blue) and Mesh AP (Yellow) 10 and 20 MHz channels that should be used when configuring the Gateway and Mesh AP frequencies. When the Backhaul falls into the “Low Band” the Mesh AP should be configured to transmit in the “High Band” and vice versa.

Backhaul to Mesh Node-AP Frequency Assignments

Frequency Planning Example

Consider the following example.

Mesh Node Example

Refer to Figure Mesh Node Example, for the following example and questions.

Gateway Node Information:

• Operating BW = 20 MHz
• F_gw = 3575 MHz

Questions:

1. Determine the frequency passband for the Mesh Node and list the center channel frequencies that could be used for the Mesh AP.
2. If bandwidth was changed to BW = 10 MHz, list all the center channel frequencies that could be used for the Mesh AP.

Solution:

We have explained that F_mn = F_gw, in this case = 3575 MHz.

Since we are operating with a BW=20 MHz, we refer to Table Example Solution Summary and see that Mesh Node backhaul is operating in the filter “low pass band” range of 3570-3590 MHz. This configures the “high pass band” of 3640 to 3700 MHz for use by the Mesh AP.

The operator should then select “Preferred Frequencies” for the Mesh AP in the “high pass band”. Examples of frequencies that could be selected in the Onyx Portal for the Mesh AP are summarized below:

Example Solution Summary

Fgw = Fmn (MHz) (Backhaul Frequency, Low Band)	Fmap (MHz) 20 MHz (Mesh AP Center Channels, High Band)	Fmap (MHz) 10 MHz (Mesh AP Center Channels, High Band)
3575	3650	3645, 3675
3575	3670	3655, 3685
3575	3690	3665, 3695

Remember that this example looks at the single Mesh Node example. When more Mesh Nodes and APs are added, RF planning to avoid overlapping channels and SAS considerations will play a big role in frequency planning.

Related Documentation

• 4G Onyx Portal Operations Guide
• GM01 Mesh Node Installation Guide
• GM02 Mesh Node Installation Guide
• GXC Glossary

Contact GXC

To get in touch with GXC, please visit https://gxc.io/contact-us/.