New HCMP features in PTP 670-02-60

High Capacity Multipoint (HCMP) is an optional feature in PTP 670 where the Master ODU can form PTP links with up to eight Slave ODUs. This makes for an efficient way to build a network with a star topology.

In 670-02-60 we enhance the HCMP operation with the following features:

Extended TDD frame duration

The ODU now supports TDD frame duration up to 14286 µs, adding the following capabilities:

  • Up to 100 km maximum range
  • Up to eight HCMP Slaves per sector, for 20 MHz and 40 MHz channel bandwidth
  • Up to 4:1 (or 1:4) symmetry for two to eight slaves at 40 MHz channel bandwidth
  • Up to 4:1 (or 1:4) symmetry for two to four slaves at 20 MHz channel bandwidth

Asymmetry expert mode

A new TDD Frame Configuration Mode control has Standard and Expert options. The Expert option provides a flexible approach to configuring link symmetry in HCMP sectors, allowing individual links to be provided with additional timeslots in the uplink or downlink as required to meet differing traffic loads. This is useful where HCMP Slaves are deployed to serve different organizational functions. A license to operate an HCMP Master in the Expert mode must be purchased as an upgrade.

Dynamic allocation

The Dynamic Allocation feature allows the HCMP Master ODU to assign surplus time slots to connected Slave ODUs when the number of connected Slaves is less than the maximum configured. The temporarily-assigned time slots can then be recovered at a later time when additional Slave ODUs connect.

Optimum Master Selection

The Optimum Master Selection feature, allows an HCMP Slave to survey the whole of the selected Regulatory Band, and to then select an HCMP Master based on received signal level and free capacity. This is likely to be useful in HCMP networks deployed in tactical or rapidly-developing scenarios, where Master ODUs are operating on different RF channels, but with a shared Group ID.

Optimum Master Selection necessarily involves an increase in scan time because the Slave cannot attempt to establish a link until the scan is complete. This increase in scan time is countered by an option to administratively bar channels at the Slave ODU, limiting the scan to selected channels.

9600 bytes frame support

The Data Service in HCMP topology now supports Ethernet frame size up to 9600 bytes.