5G AP Deployment Modes
Introduction
Private cellular networks often require coverage expansion as facilities grow, production areas are reconfigured, or new operational areas are added. Traditionally, extending coverage requires deploying additional Access Points (APs), increasing infrastructure costs, cabling requirements, configuration complexity, and ongoing operational management.
Multi-Port Attach is a dual-sector coverage feature that enables a single AP to serve two distinct or geographically separated operational areas. By partitioning a supported 4×4 AP into two independent 2×2 MIMO sectors, operators can independently direct high-gain, narrow-beam antennas toward different coverage areas while continuing to use a single AP. Each sector operates independently with its own 2×2 MIMO configuration, preserving the spatial diversity and antenna gain required to deliver optimal RF performance within its intended coverage area. This approach is especially valuable in uplink-heavy use cases, where a strong link budget from each sector is critical to reliable performance, without compromising uplink strength to gain coverage.
Although the physical RF implementation changes, the deployment continues to operate as a single AP and a single NR Cell, preserving the existing logical network architecture.
Key Benefits
Multi-Port Attach provides the following operational and deployment benefits:
Operational Benefits:
Reduces the number of APs required to cover a facility.
Reduces infrastructure, installation, and maintenance costs.
Simplifies network management by preserving existing operational workflows.
RF Coverage Benefits:
Improves directional RF coverage for geographically separated operational areas.
Maximizes spectrum efficiency by allowing both sectors to share the same operating channel, eliminating the need to allocate separate channels for each coverage area.
Simplifies frequency/channel planning, since both sectors run on the same channel, only a single channel needs to be planned for the entire deployment instead of one per coverage area.
Preserves antenna gain and 2×2 MIMO operation for each sector.
Supports heavy-uplink use cases by maintaining a strong per-sector link budget instead of trading gain for broader coverage.
Mobility Benefits:
Keeps UE attached to the same logical NR Cell while moving between coverage areas, eliminating inter-sector handover signaling and associated control-plane overhead.
Maintains consistent service continuity across both coverage areas.
Standard 4×4 versus Multi-Port Attach
The following figure compares a standard 4×4 AP deployment with a Multi-Port Attach deployment, illustrating how a supported 4×4 AP can be partitioned into two independent 2×2 sectors while continuing to operate as a single AP and a single NR Cell.
Figure: Standard 4×4 Configuration versus Multi-Port Attach
Deployment Scenarios
Multi-Port Attach is intended for deployments where two physically separated operational areas can be served by a single AP while maintaining a single logical network. Typical deployment environments include:
Warehouses
Manufacturing facilities
Distribution centers
Long corridors
Transportation platforms
Outdoor yards
Mixed indoor/outdoor environments
RF Coverage Comparison
The following figures compare a standard 4×4 deployment with a Multi-Port Attach deployment and illustrate how partitioning a supported 4×4 AP into two independent 2×2 sectors improves RF coverage for two distinct or geographically separated operational areas.
Figure: Standard 4×4 Mode
In a standard deployment, all four antenna ports operate together as a single 4×4 MIMO sector, providing RF coverage through a single antenna pattern. This approach may result in reduced signal quality at the edges of geographically separated operational areas.
Figure: Multi-Port Attach Mode
In a Multi-Port Attach deployment, the AP antenna ports split into two independent 2×2 sectors. Each sector can be connected to a dedicated directional antenna to provide optimized RF coverage for its intended operational area while both sectors continue operating as part of the same NR Cell. This is the core benefit of the feature — going from one antenna to two lets you direct each sector into a different area while each sector keeps its own strong uplink budget, neither sector “splits” its uplink gain with the other.
When to Use Multi-Port Attach
Use Multi-Port Attach when:
Improving RF coverage is the primary deployment objective.
Two geographically separated operational areas can be effectively served by one supported AP.
Maintaining a single logical network architecture is preferred.
Reducing additional infrastructure without compromising RF design is desirable.
When Multi-Port Attach Is Not Appropriate
Do not use Multi-Port Attach when:
Additional network capacity is required.
Independent NR Cells are required.
RF planning indicates that additional APs are required.
The intended coverage areas cannot be effectively served by a single AP.
Unsupported hardware is deployed.
Architecture
Multi-Port Attach partitions the AP's four antenna ports into two independent 2×2 MIMO sectors, each connected to its own directional antenna system. Although the physical RF implementation changes, the deployment continues to behave as a standard single-cell network.
Direct AP Deployment
In a direct deployment, the Onyx Edge hosts a single NR Cell that is connected directly to one supported AP. When Multi-Port Attach is enabled, the AP provides two independent 2×2 MIMO sectors while the Distributed Unit (DU) continues to manage the deployment as a single NR Cell. This deployment model is well suited for environments where a single supported AP can provide RF coverage for two geographically separated operational areas while maintaining a single logical network.
Figure: Direct AP Deployment
FHM-Managed Multi-AP Deployment
In an FHM-managed deployment, the Onyx Edge hosts a single NR Cell that connects to one or more supported APs through a Fronthaul Multiplexer (FHM). When Multi-Port Attach is enabled on a supported AP, the AP partitions its antenna ports into two independent 2×2 MIMO sectors while the DU continues to manage the deployment as a single NR Cell.
The FHM provides fronthaul connectivity between the Onyx Edge and the APs but does not change the logical operation of Multi-Port Attach.
Figure: FHM-Managed Deployment
Logical Network and Physical RF Architecture
Multi-Port Attach preserves the logical network architecture while modifying only the physical RF implementation. This separation enables the deployment to continue operating as a single AP and a single NR Cell.
Antenna Resource Partitioning
Multi-Port Attach partitions the four antenna ports of a supported 4×4 AP into two independent 2×2 MIMO sectors. The validated antenna port assignments are Sector A: Ports 1 and 2, and Sector B: Ports 3 and 4. Each sector maintains an independent 2×2 MIMO configuration while operating on the same carrier and within the same NR Cell.
Single NR Cell Operation
Although RF coverage is provided through two independently directed antenna sectors, Multi-Port Attach continues to operate as a single NR Cell.
Both sectors:
Broadcast the same NR Cell.
Operate on the same carrier.
Share the same cell configuration.
Are managed by the same DU.
Operate through the same AP.
From the UE perspective, the deployment appears as a single NR Cell throughout the coverage area.
SAS / CBRS Support
Multi-Port Attach supports both SAS-enabled and non-SAS deployments.
In SAS-enabled deployments, the AP functions as the CBSD, while the SAS authorizes spectrum operation. Multi-Port Attach changes only the physical RF implementation and does not alter the relationship between the AP and the SAS.
When Multi-Port Attach is enabled, each configured antenna gain generates a corresponding CBSD record. These CBSD records are registered independently with the SAS, enabling independent spectrum authorization for each antenna configuration while the deployment continues to operate as a single AP and a single NR Cell.
In direct AP deployments, each configured antenna gain generates a corresponding CBSD record, which is registered with the SAS — allowing independent antenna and power management for each sector. In FHM-managed deployments, each AP generates its own CBSD records based on its configured antenna gain values, enabling independent spectrum authorization per AP and sector while maintaining a common operating channel across the deployment.
For complete information about SAS deployment prerequisites, CBSD configuration, registration, spectrum grants, and operational procedures, refer to the Onyx CBRS SAS Registration Application Note.
Deployment Prerequisites & Planning
Successful Multi-Port Attach deployments begin with proper planning. Before enabling the feature, verify that the deployment environment, hardware, software, and RF design meet the deployment requirements. Completing these activities before making configuration changes helps reduce deployment risk and simplifies post-deployment validation.
Before deploying Multi-Port Attach, complete the following planning activities.Verify Existing Deployment — Before enabling Multi-Port Attach, verify that the existing deployment is operating normally. Resolving existing issues before deployment significantly reduces implementation risk.
Verify that the Onyx Edge is operational.
Verify that the AP is online and operational.
Verify that the existing NR Cell is operational.
Resolve any existing alerts or configuration issues before proceeding.
Verify Hardware and Software Compatibility — Verify that all platform components support Multi-Port Attach before beginning deployment.
Plan RF Coverage — Multi-Port Attach is designed to improve RF coverage rather than increase network capacity. Proper RF planning is essential for achieving the intended coverage objectives.
Identify the operational areas that require RF coverage.
Verify that both areas can be effectively served by a single supported AP.
Determine antenna placement and orientation for each sector.
Ensure sufficient RF overlap where seamless UE mobility is required.
Frequency/channel planning is simplified. Both sectors operate on the same channel, so only one channel needs to be planned for the entire deployment.
Define Deployment Objectives — Clearly define the objectives before enabling Multi-Port Attach. Typical deployment objectives include:
Extending RF coverage to two geographically separated operational areas.
Improving RF coverage without deploying an additional AP.
Maintaining a single logical network architecture.
Optimizing infrastructure utilization while preserving RF performance.
CBRS Deployment Considerations — For deployments operating in CBRS spectrum:
Verify that the SAS environment has been prepared.
Complete all required SAS configuration before enabling Multi-Port Attach.
Verify that CPI requirements have been completed, if applicable.
For detailed SAS prerequisites, CBSD configuration, and deployment procedures, refer to the Onyx CBRS SAS Registration Application Note.
Deployment Design Considerations
When designing a Multi-Port Attach deployment, consider the following recommendations.
RF Design
Perform an RF site survey before deployment.
Identify the operational areas to be served.
Select antennas appropriate for the deployment environment.
Validate antenna orientation and placement.
Ensure sufficient RF overlap where seamless UE mobility is expected.
Minimize physical obstructions that may affect signal propagation.
Platform Design
Verify that the AP supports Multi-Port Attach.
Verify compatible GXC Onyx software versions.
Confirm that the required feature licenses are installed.
Review the applicable release notes before deployment.
Coverage Planning
Align each RF sector with its intended operational area.
Validate the expected RF coverage before deployment.
Identify RF measurement locations for post-deployment verification.
Define acceptance criteria for coverage validation.
Design RF coverage to meet operational requirements rather than simply extending coverage distance. Proper antenna selection, orientation, and placement are the primary factors that determine a successful Multi-Port Attach deployment.
Feature Limitations & Considerations
Review the following limitations and considerations before deploying Multi-Port Attach. Understanding these constraints helps ensure that the feature is deployed in supported environments and according to validated design practices.
Multi-Port Attach is supported only on 5G Onyx Edge (NR+Core) deployments.
Multi-Port Attach transition constraints apply to SAS-enabled deployments. Before changing the Multi-Port Attach state, remove all SAS-enabled cells from the deployment. Refer to Deploy Multi-Port Attach.
Enabling Multi-Port Attach reduces the maximum theoretical downlink throughput available to each sector. Partitioning a 4×4 RU into two independent 2×2 sectors reduces the number of available downlink spatial layers from four to two per sector. This is an intentional design trade-off that improves RF coverage flexibility rather than increasing capacity or user density. Consider this reduction during network planning.
Multi-Port Attach improves RF coverage but does not increase network capacity or support higher user density within a single coverage area. Deployments requiring additional capacity should use additional APs rather than Multi-Port Attach.
CAUTION: Sustained Maximum-Throughput Traffic — When Multi-Port Attach is enabled, sustained simultaneous maximum-rate UDP or TCP traffic across all active antenna ports may cause the Onyx Edge to reboot unexpectedly. This behavior occurs only when all active antenna ports are driven at maximum throughput simultaneously. Lower-bandwidth traffic, such as ICMP ping, is not affected.
Configure Multi-Port Attach
This section describes how to configure Multi-Port Attach. Before beginning deployment, complete the planning activities described in Deployment Prerequisites and Planning.
The following diagram summarizes the end-to-end workflow for enabling Multi-Port Attach on an Onyx Edge, from verifying its current status through the point where the configuration diverges into a non-SAS path and a SAS-enabled path.
Figure: Multi-Port Attach Configuration Workflow
View Multi-Port Attach Status
Before configuring Multi-Port Attach, verify the current Multi-Port Attach status for the target Onyx Edge.
To view the Multi-Port Attach status of the target Onyx Edge (NR+Core):
Navigate to Equipment > Onyx Edge (NR+Core) tab or Onyx Edge tab.
In the Onyx Edge (n) panel, click the Onyx Edge's name.
The <onyx-edge-name> page > RAN section > Multi-Port Attach parameter indicates the Multi-Port Attach feature's status — True (enabled) or False (disabled).
Onyx Edge with Multi-Port Attach disabled (False).
In CBRS deployment, with Multi-Port Attach disabled (False) and SAS status Authorized:
In CBRS deployment, to view the cell's CBSD details, click the Show More link. Cell details showing CBSD information for the single-antenna configuration:
Add Cell Parameter Reference
The following tables define the cell configuration parameters required when adding a new NR cell with Multi-Port Attach enabled, referenced in Enable and Configure Multi-Port Attach. Parameters vary by band and whether SAS is enabled for the cell.
Table: Parameters Applicable to N48 with SAS Disabled, N77, and N78 Bands
SAS Enabled
Click the toggle switch to disable SAS. Default: disabled.
Name
(Required) The cell's name.
BW (MHz)
(Required) Click to select the cell's channel bandwidth from 10, 20, 40. Select the bandwidth appropriate for the deployment and RF design.
Freq (MHz)
(Required) Click to select the cell's operating center frequency. Available frequencies depend on the selected band and system configuration.
Associated AP/FHM [Band N**]
Click to select the associated AP/FHM.
PSS (for PCI)
(Required) Click to select the Primary Synchronization Signal (PSS) from 0, 1, 2. The PSS contributes to the Physical Cell Identity (PCI). Configure a value that results in a unique PCI within the RF environment to minimize interference with neighboring cells.
Table: Parameters Applicable to N48 Band with SAS Enabled
SAS Enabled
Click the toggle switch to enable SAS. Default: disabled.
Name
(Required) The cell's name.
User ID
(Required) The SAS account's user ID. This identifier is included during CBSD registration to authenticate ownership of the CBSD.
Preferred BW (MHz)
(Required) Click to select the preferred channel bandwidth requested during SAS grant acquisition from 10, 20, 40. The SAS attempts to allocate spectrum matching this bandwidth, subject to spectrum availability and regulatory constraints. Default: 40 MHz.
Preferred Freq (MHz) in Priority Order
(Required) Click to select one or more preferred center frequencies, listed in order of preference — highest priority first. During grant acquisition, the SAS attempts to assign the highest-priority available frequency.
Strict Freq Preference
(Required) Click to specify whether the selected preferred frequencies must be strictly adhered to. Default: True. When True, grant requests are limited to the preferred frequency range (the system may fall back to a lower bandwidth at the same frequency if needed). When False, the next best frequency will be requested for the grant.
PSS (for PCI)
(Required) Click to select the Primary Synchronization Signal (PSS) from 0, 1, 2. The PSS contributes to the Physical Cell Identity (PCI). Configure a value that results in a unique PCI within the RF environment to minimize interference with neighboring cells.
Access Point Association
Associated AP/FHM
(Required) Click to select the AP or FHM to associate with this cell. Selecting an FHM enables unified control of SAS settings for all APs associated with that FHM.
CBSD Category
(Required) Click to select the CBSD category — Category A for devices operating at a maximum of 30 dBm EIRP, Category B for devices operating at a maximum of 47 dBm EIRP. Default: A.
Antenna Gain <n> (dBi)
(Required) The antenna gain in decibels relative to an isotropic radiator (dBi). Enter an integer value in the range of 0–35. Default: 0. For Multi-Port Attach deployments, configure two values — Antenna Gain 1 and Antenna Gain 2 — one per sector.
To add Antenna Gain 2, click 
.
Enable and Configure Multi-Port Attach
Multi-Port Attach is configured at the Onyx Edge level, is disabled by default, and can be enabled or disabled independently for each Onyx Edge.
To enable and configure Multi-Port Attach for an Onyx Edge:
Navigate to Equipment > Onyx Edge (NR+Core) tab or the Onyx Edge tab.
For the Onyx Edge that you want to configure, in the Onyx Edge (n) panel > Actions column, click the corresponding ⋮ (options) icon, then click Edit.
The Edit Onyx Edge (<onyx edge name>) page is displayed.
Click the RAN tab.
If the Onyx Edge contains any SAS-enabled cells, delete them before continuing:
For each SAS-enabled cell, click the corresponding ⋮ (options) icon, then click Delete.
Confirm the deletion when prompted.
Click Save Onyx Edge to save the configuration with the cell(s) removed.
To enable the Multi-Port Attach feature, toggle the Multi-Port Attach switch on.
To add a cell, click Add Cell.
The Add Cell dialog box is displayed.
N48 band with SAS disabled, N77, and N78 bands:
N48 band with SAS enabled:
Enter the required details and click Submit.
For parameter descriptions, see Add Cell Parameters Reference.
Sample configuration screens:
SAS disabled:
SAS enabled with two Antenna Gain configured:
To save your edits, in the top right corner of the page, click Save Onyx Edge.
SAS-Enabled Deployments
The deployment workflow for SAS-enabled networks is the same as for non-SAS deployments, with the additional SAS configuration required before RF transmission can begin. For how CBSD records are generated and registered per sector, see SAS / CBRS Support.
When Multi-Port Attach is enabled:
Each configured antenna gain generates a corresponding CBSD record.
Each generated CBSD is registered independently with the SAS.
Spectrum grants are managed independently for each CBSD.
Transition Constraints
When changing the Multi-Port Attach state in a SAS-enabled deployment:
Remove all SAS-enabled cells before enabling or disabling Multi-Port Attach.
Save the configuration before adding the required cells.
For SAS account setup, CPI requirements, CBSD registration, spectrum grants, heartbeat procedures, and troubleshooting, refer to the Onyx CBRS SAS Registration Application Note.
Verify the Deployment
After deploying Multi-Port Attach, verify that the configuration has been successfully applied and that the deployment is operating as expected. Validation should begin by confirming that the configuration has been applied correctly in the Onyx Portal, followed by verification of platform health, RF coverage, UE connectivity, and, where applicable, SAS authorization.
Verify the Configuration
Immediately after saving the configuration, verify that Multi-Port Attach has been successfully applied.
To verify the Multi-Port Attach configuration:
Navigate to Equipment > Onyx Edge (NR+Core) tab or the Onyx Edge tab.
In the Onyx Edge (n) panel, click the Onyx Edge's name.
In the RAN section, verify Multi-Port Attach status:
Multi-Port Attach enabled (True) with the new cell's details.
In CBRS deployment, Multi-Port Attach enabled (True) with cell's SAS status Authorized.
In CBRS deployment, to view the cell's CBSD details, click the Show More link.
Verify that:
Two CBSD records are displayed for the NR Cell (one for each 2×2 sector).
Both CBSD records show an Authorized SAS status.
Verify Platform Status
Confirm that:
The Onyx Edge is online.
The AP is online.
The NR Cell is operational.
No critical alerts are active or configuration errors are reported.
Verify RF Coverage
Perform RF validation within each intended coverage area.
Verify that:
Sector A provides the expected RF coverage.
Sector B provides the expected RF coverage.
Signal strength meets the planned design objectives.
Sufficient RF overlap exists where seamless UE mobility is expected.
Compare the measured RF coverage against the deployment objectives established during planning.
Verify UE Connectivity
Using one or more test UE, verify that devices can successfully access the network.
Confirm that the UE:
Detects the NR Cell.
Successfully attaches to the network.
Receives an IP address.
Successfully exchanges user traffic.
Verify UE Mobility
Verify that UE can move between the two operational areas while remaining connected to the same NR Cell.
Confirm that:
Connectivity is maintained while moving between sectors.
No service interruption occurs.
No unexpected RRC re-establishment occurs.
No UE reattachment occurs during normal mobility.
Related Documentation
GXC 5G AP Hardware Installation Guides
Onyx CBRS SAS Registration Application Note
5G Onyx Portal Operations Guide
Contact GXC
To get in touch with GXC, please visit https://gxc.io/contact-us/.
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