Smooth Hand-Off from Digital to Analog

Maintain Smooth Hand-Off from Digital to Analog Without Installing a Transmission Interface at Every Ericsson 882 Radio Base Station

Problem
Plans are in place to introduce digital within the core market, but you need to make sure all your digital subscribers in the outer fringe areas experience a smooth hand-off to analog radio base stations. Also, some of your roaming customers are complaining that their dual-mode phones drop calls when entering or leaving the analog-only part of your systems. Budgetary constraints prevent a total digital deployment at all radio base stations.

Solution
Coastcom's digital Mini-cell equipment can be configured to support digital locating verification module (LVM) transceivers. The equipment consists of two D/I Mux III T1 multiplexers, using CDCU channel cards. A single locating LVM digital transceiver at a remote Mini-cell, co-located with Coastcom equipment, allow smooth mobile assisted hand-off to analog transceiver radios at that cell site. The transmission interface (TRI) can be up to 50 miles away from the cell site, reducing hardware and T1 deployment costs significantly.

How Does It Work?
The CDCU is a special data card that interfaces to the RTT in the TRI control equipment. Multiple cell sites are supported by an MTSO that has been set up with an ERI/TRI configuration. By configuring the D/I Mux III in drop-and-insert mode and intercepting the existing T1 facility at the cell site, the LVM is supported without the need for a dedicated TRI or T1 facility. This option can be used to connect to a "compact" MTSO or DACS at the MTSO.

How Do You Set It Up?
This configuration allows the LVM access to the existing T1, providing there are spare DS0s (64 Kbps). The drop-and-insert configuration provides the flexibility to use any DS0 in the T1, so that channel 9 can continue to support the STR/STC data connection to the MTSO. MDEQ IDs and the mobile verification MVER programming in the MTSO are similar to a conventional installation.

Figure c5. LVMs Support Smooth Hand-Off "Drop-and-Insert"

What Information Do You Need?

1. What is the distance between the MTSO and each radio base station, and what is the medium (microwave, fiber, or local phone company T1)?

2. How many LVMs are you planning to deploy at remote cell sites?

3. Are you using compact or non-compact hardware?

You'll need an LVM for each site, and a centrally located Exchange Radio Interface/Transmission Interface (ERI/TRI).

Remote Frame Location

Remotely Locate a Frame of Ericsson 882D Digital Transceiver Modules Up to 50 Miles From a Centrally Located ERI/TRI Control Rack

Problem
Plans are in place to introduce digital TDMA within the core market, but all subscribers need dual mode analog and digital, including those in outlying areas. Therefore, a cost-effective solution is needed to provide digital TDMA to a number of existing radio base stations.

Solution
Coastcom's digital Mini-cell equipment can be configured to support both digital LVM and Digital Transceiver Modules (DTRM). The equipment consists of two D/I Mux III T1 multiplexers, using Digital Cellular Unit (CDCU) channel cards. Full digital support can be achieved by installing both an LVM and DTRM digital transceivers at the remote radio base station, and co-locating Coastcom equipment. The TRI can be up to 50 miles away from the cell site, reducing hardware and T1 deployment costs significantly.

How Does It Work?
The CDCU is a special data card that interfaces to the Radio Transceiver Terminal (RTT) in the TRI Ericsson control equipment. Multiple cell sites are supported at a MTSO that has been set up with an ERI/TRI configuration. Configuring the D/I Mux III in drop-and-insert mode and intercepting the existing T1 facility at the cell site supports DTRMs and LVM, making a dedicated TRI or T1 facility unnecessary. This option is used to connect to a compact MTSO or DACS at the MTSO.

Figure c6. Remote DTRM and LVM Mini-cell "Drop-and-Insert" Over an Existing Network

How Do You Set It Up?
This configuration allows access to the existing T1, providing there is at least one spare DS0 (64 Kbps) for the LVM and four spare DS0s (256 Kbps) for each DTRM on each radio base station T1 facility. The drop-and-insert configuration enables use of any DS0 in the T1, allowing channel 9 to continue supporting the STR/STC data connection to the MTSOs. This ERI/TRI can support digital at multiple remote RBSes.

Figure c7. Dual Channel Bank, Adding Analog and Digital Capacity

This option is used in low-capacity cell site, but expansion is readily available by reconfiguring the D/I Mux III to dual channel bank mode. This adds another T1 to expand either the analog or digital coverage. The MBLT is reconnected to the D/I Mux III over a TTU channel card. EDCU channel cards are added to support additional DTRMs at that cell site.

The MDEQ device IDs and MVER data-fill in the MTSO are similar to those in a conventional installation, necessitating no special programming.

What Information Do You Need?

1. What is the distance between the MTSO and each radio base station, and what is the medium (microwave, fiber, or local phone company T1)?

2. How many LVMs are you planning to deploy at remote cell sites?

3. How many DTRMs are you planning to deploy at remote cell sites?

4. Are you using compact or non-compact Ericsson hardware?

To complete the electronics needed for the Mini-cell, you will need to order the transceiver radio rack(s), the antenna, and power systems.

Remote Sector Support of the Dual-Mode Mini-cell

Create a Remote Sector to Support a Dual-Mode "Analog and Digital" Mini-cell

Problem
Approval has been given to add a number of new cell sites supporting both analog and digital TDMA, including outlying areas. A cost-effective solution is needed to achieve maximum deployment and coverage.

Solution
Coastcom's hybrid Mini-cell equipment can be configured to support both digital and analog transceivers. The equipment consists of two D/I Mux III special T1 multiplexers equipped with CEL1 SDCU, CDCU, TTU, SDM, and 4-Wire TO channel cards. Installing one or more racks of transceivers at the remote radio base station and co-locating Coastcom equipment offers full analog and digital support. Also, the ERI/TRI can be located up to 50 miles away at a donor cell site. The cost associated with the ERI/TRI equipment, MBLT and ETC/STC hardware in the MTSO can be amortized over two or more cell sites. Savings in hardware and T1 facilities can reduce deployment costs significantly.

How Does It Work?
The hybrid Mini-cell combines an analog and a digital Mini-cell. Similar to previous examples, the hybrid Mini-cell is configured as a remote sector of the Donor-cell site. The MDIO data for ATRM control transmits over the CEL1 SDCU link. The DTRM digital voice channels with data control information are each linked via a CDCU to RTT equipment at the donor cell site. The analog VF channels are passed over the 4-Wire TO channel cards to a TTU channel card at the donor4-Wire TO, while the TTU interfaces to an ETB card on the TRI equipment. From here the TRI cross-connects the various analog and digital voice channels use in cross-connecting analog and digital voice channels from both the donor and Mini-cell, passing these over T1 facilities to the MTSO. The link also includes STR/STC data control channel 9.

An alarm unit terminates up to 16 remote alarms, and interfaces to an SDM channel card in the D/I Mux III. The alarm unit at the donor closes the contact(s) to the IOIM should alarms activate at the Mini-cell. This option connects to both compact and non-compact Ericsson hardware.

How Do You Set It Up?
This Mini-cell configuration is ideal for fringe markets where lower capacity cell sites are needed. For example, six analog and nine digital voice channels could be located at the Mini-cell. This capacity could be doubled by activating the dual channel bank feature on the D/I Mux III and connecting a second T1 facility. Digital bandwidth allocation is limited to one DS0 (64 Kbps) for the LVM and each ATRM (analog voice channel), four DS0s (256 Kbps) for each DTRM and/or CEL1 SDCU, and one DS0 for the alarm feature. At the donor, the TRI distributes the MBLT voice channels to the RTT or the ETB, which are remotely connected to the Mini-cell. This ERI/TRI can support analog and digital at multiple remote Mini-cells. The MDEQ device IDs and data from the MCC, MLOC, MVER, MVC, and MDVC programming in the MTSO is similar to a conventional installation, necessitating no special programming.

Figure c8. Hybrid Mini-cell for Analog and Digital Point-to-Point

What Information Do You Need?

1. How many MVC/ATRM voice channels do you require at each Mini-cell, and how many voice channels are you already using at the donor?

2. How many MDVC/DTRM voice channels do you require at the Mini-cell, and how many voice channels are you already using at the donor?

3. What is the distance between the donor and Mini-cell sites, and what is the medium (microwave, fiber, or local phone company T1)?

4. How many sectors are you planning to deploy at each Mini-cell?

5. Are you using compact or non-compact hardware, and what contingency requirements do you have at the donor (redundant EMDM, STRs, power)?