Communication Network Design in Grid Management
I. Comparison of Communication Technologies
Currently, management in various government departments is generally implemented through grid management. Grid communication typically requires two physically isolated networks — the government industry private network and the government portal website — and sometimes additional networks such as surveillance networks and video conference networks. Some of these networks have high confidentiality requirements, and physical isolation between networks is mandatory, especially in industries with strict confidentiality requirements such as the military and public security, where VLAN-based isolation between networks is strictly prohibited.
At present, most grid management communication methods rely on public 3G/4G mobile networks or leased broadband networks. Even with additional confidentiality measures, the level of security provided is not high. Some solutions lease E1 private lines, which can meet confidentiality requirements, but the transmission bandwidth is limited and cannot adequately support higher video transmission demands. In addition, the leasing cost of E1 lines is relatively high.
Therefore, grid management communication typically adopts leased dark fiber. At present, the three major telecom operators and local radio and television networks have laid fiber optic cables to administrative villages in many areas, providing ample resources for fiber leasing in grid management.
Typically, multiple physically isolated network transmissions must be implemented over the fiber, along with dispatch telephones, audio monitoring for service quality supervision, and in some cases, wireless trunking forwarding services within the grid.
Three types of equipment can typically be used for remote communication over dark fiber. Given the large number of remote terminals, expensive equipment such as SDH and OTN is not considered here; only Media Converters, PON, and TDM multiplexing technology (PDH+PCM) are considered. The three technologies are compared below.
| PON | TDM（PDH+PCM）Optical Transmission |
1. Transmission Service Types | Only 1 Ethernet | 1 Ethernet, Telephone, Serial Port | Multiple line-rate 100M or line-rate Gigabit Ethernet, multiple Telephone, Serial Port, E1, etc. |
2. Transmission Technology | Packet Switching | Packet Switching and Softphone | TDM Time-Division Transmission |
3. Isolation Technology | VLAN Virtual Isolation | VLAN Virtual Isolation | TDM physical isolation provides better performance |
4. Confidentiality | Low; any fiber optic transceiver can interoperate. If VLAN isolation is used, not only is bandwidth reduced, but all useless packets also reach the port, making it easy to decipher. | Medium; VLAN isolation not only reduces bandwidth, but all useless packets also reach the port, making it easy to decipher. | High; isolated channels occupy independent bandwidth, line-speed network bandwidth remains unchanged, and only useful information packets are transmitted to the user port. |
5. Technical Complexity | Low | High | Medium |
6. Transmission Distance | Large | Small | Large |
7. Telephone Dispatch Technology | Soft dispatch, high latency | Soft dispatch, high latency | Supports dispatch via bothTDM switching and soft switching technologies, with low latency |
8. Number of optical fibers required for physically isolated networks | Multi-core | Multi-core | A single optical fiber is sufficient |
9. Network Topology Types | Point-to-Point | Tree | Tree |
10. Transmission Bandwidth | Bidirectional Symmetric | Downstream bandwidth greater than upstream, unsuitable for video surveillance | Bidirectional symmetric, suitable for video transmission |
11. Cost of implementing voice communication | High | Medium | Low |
12. Transmission Delay | Large transmission delay, no guarantee | Large transmission delay, no guarantee | Small, fixed transmission delay |
In PON, due to the transmission bandwidth exceeding 1G, the transmission distance of the optical module (which decreases as bandwidth increases) is relatively small. Additionally, the use of ODN optical splitters increases optical attenuation, further reducing the transmission distance significantly. Generally, the upstream bandwidth is small, making the PON network unsuitable for fiber transmission in video surveillance applications.
II. Multi-Channel Transmission System with Upstream and Downstream Transmission Bandwidth
When telephone, voice monitoring, and wireless trunking micro-base station relay are required, TDM-based optical transmission offers significant advantages.
PDH and PCM technologies in TDM optical transmission are among the earliest communication technologies, with high technical maturity. Today, PDH has been enhanced with multiple line-rate 100M and Gigabit channel optical transmission capabilities, giving it renewed vitality.
Raytrans' TDM-based optical transmission technology includes central office equipment, aggregation point equipment, and terminal equipment, sharing the same topology as PON networks. In environments with video surveillance and long transmission distances, it is the optimal alternative to PON networks.
Raytrans TDM transmission system includes central office equipment IDM G3CP, aggregation node equipment IDM GP-MPconv, and remote user access equipment IDM NTD421.
In the fiber link from the central office to the aggregation node, the fiber transmission bandwidth is 2.5G, capable of transmitting two groups of physically isolated Gigabit line-rate Ethernet and dozens of E1 channels.
The optical fiber transmission bandwidth from the aggregation node to the remote end is 250M, capable of transmitting two groups of wire-speed 100M Ethernet and several groups of E1 channels. E1 channels are typically used for narrowband services such as telephone, voice, and serial data transmission. Currently, it can support up to 2 telephone lines, one audio EM2/4-wire with adjustable gain (for connecting to radio base stations or audio monitoring), and one RS422/RS485 interface.
The relatively low optical fiber transmission bandwidth from the aggregation node to the remote end helps increase the transmission distance.
The central device IDM G3CP is not only a transmission device but also features rich PCM access functions, along with powerful information switching and aggregation capabilities:
- It can aggregate all broadband Ethernet services;
- It can perform non-blocking cross-connection for all remote 64K (or N*64K) services, with a cross-connection capacity of 128E1*128E1;
- It can aggregate all remote serial ports via Ethernet interfaces, functioning as a serial server;
- It can switch remote telephone calls, functioning as an integrated telephone exchange;
- It can dispatch remote telephone, voice, and video, meeting the requirements of multimedia dispatch communication, and can also integrate SMS sending and fax sending/receiving functions;
- It can access telephone services from higher-level or adjacent units, with access methods including EM2/4, FXO, No.7 signaling, No.1 signaling, ISDN PRI signaling, etc., including satellite phones and wireless trunking;
- It can connect to dispatch consoles, supporting up to 250 dispatch consoles for joint control. The dispatch console software also integrates GIS geographic information system software, enabling comprehensive dispatch of wired, wireless, voice, data, video, and location information.
III. Functions of the Dispatch Center Dispatch Console:
- Map design is primarily targeted at XX City.
- Click "GIS" to open, and the interface is displayed as follows:
- The interface is divided into two parts: the location list on the far left and the XX City map on the right.
- The map image can be zoomed in and out within a certain range. The clickable range for markers needs to be set to an acceptable tolerance.
- First, mark locations on the map (markers can be added by the user; currently, markers are placed at locations listed on the left). Then, click a location name in Table 1, such as "Tuanhe Street," and the map will display the marker at that location.
- Clicking a marker allows you to select operation functions (phone, video, monitor).
To make a call, first lift the handset, then click the "Phone" button to initiate the call.
To view the video at that location, click the "Video" button, and a small video window will pop up, as shown below:
The monitoring function is also available. Speakers and pickups are placed at the location. Adding the speakers and the dispatch console handset to the same conference room enables monitoring. You can select the conference room (e.g., the left speaker and right speaker can be in different conference rooms). Click the "Monitor" button to pop up a selection window.
Simply select the object to be monitored.
IV. Configuration of Communication Rooms and Command Centers in Grid Management:
The communication room must meet the physical isolation requirements of the government portal website and the government intranet, while also providing interfaces for dispatch telephones, public network telephones, SMS, and fax.
Communication Room Equipment:
No. | Equipment | Qty | Unit Price | Total | Remarks |
1 | Firewall | 1 |
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| Run the firewall system; all remote users connect to the external network through this firewall.
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2 | Public Opinion Monitoring Server | 1 |
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| Internet Behavior Management and Public Opinion Management Software Platform |
3 | Multi-port Router | 1 |
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| Provides broadband access to multiple operators, reducing the probability of network failure |
4 | Portal Server | 1 |
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| External Publicity |
5 | Government Cloud Processing Server | 1 |
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| Cloud Storage, Cloud Computing |
6 | Intranet Web Server | 1 |
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| OA System and Grid Software Operating Platform |
7 | Voice Dispatch Communication Server | 1 |
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8 | Call Center Server | 1 |
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9 | Internal/External Network Information Security Gateway | 1 |
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| Used for data switching between internal and external networks |
10 | Database Software | 1 |
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11 | Related Software Development |
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Load balancing devices are not considered for now. As business volume increases, two load balancers can be deployed later to achieve load balancing for all application systems. Meanwhile, the two devices can form an HA pair; if one load balancer fails, the other can continue operating, thereby ensuring system stability.
Two WEB servers can also be used, both running Linux systems, connected to the load balancing system at the front end. On one hand, this reduces the load on the main server; on the other hand, if one server fails, the other can continue working.
In the later stage, disaster recovery mirror servers can be added: deploy two servers in a telecom or mobile data center to perform remote backup of system data and programs, ready to start up and replace the main platform system for emergency operation in case of an unexpected interruption.
The command center is used for video surveillance, audio monitoring, dispatch telephony, portal website, intranet information display, big data processing, etc., on the user side.
The main configuration of the command center is:
No. | Equipment | Qty | Unit Price | Total |
Remarks |
1 | Audio Mixing Console | 1 |
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2 | IP Video Decoding Matrix | 1 |
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3 | VGA Video Switching Matrix | 1 |
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4 | Large Screen Splicing Server | 1 |
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5 | Video Wall | N*M |
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6 | Speaker | 2 |
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7 | Microphone | N |
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8 | Printer | 1 |
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9 | SMS Gateway | 1 |
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10 | Custom control console with telephone | N |
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11 | Console Computer | N Units |
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12 | Intelligent Lighting Control System | 1 |
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13 | Fresh Air System Controller |
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No. | Equipment | Qty | Unit Price | Total |
Remarks |
1 | Multimedia Dispatch Software | 1 |
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2 | Call Center Software | 1 |
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Central Office Equipment:
Must provide SDH interfaces STM-1 and STM-4, enabling connection to the operator's SDH optical fiber communication network for interconnection with higher-level units or other business units within the city.
Must provide 200M bandwidth (2 wire-speed 100M) optical fiber interfaces to each node, along with telephone and voice services. To conserve fiber count, the optical fiber to township/subdistrict must be capable of transmitting 2000M (2 wire-speed 1000M Ethernet) and more than 10 E1 channels. After reaching the township, low-speed optical fiber interfaces (with a maximum single-fiber distance of 80KM for extended reach) shall be used to connect to administrative villages.
The central office equipment must integrate scheduling functionality to manage communication resources within the remote grid, specifically:
Basic Functions: Call, call transfer, call forwarding, park, answer, barge-in, hold/resume, do-not-disturb setting, and other operations.
Scheduling Functions: Barge-in, forced release, call pickup, monitoring, call barring, manual/automatic transfer, group call, group call, conference, dynamic grouping, hierarchical collaborative scheduling, and other operations.
Broadcast Functions: Broadcast, loudspeaker announcement, environmental monitoring, etc. Broadcast includes instant broadcast and scheduled broadcast. Broadcast audio sources can be selected from internal sound files, external audio sources, or TTS files for playback.
Trunking Intercom: Capable of scheduling intercom units of different frequency bands, different models, and different standards (digital/analog); voice control can be performed via the scheduling software interface.
Conference Functions: Conference initiation, conference scheduling, conference member identity authentication, multi-group conferences, conference process monitoring, and other operations.
The provided scheduling software must be able to integrate with GIS geographic information systems and synchronized surveillance recordings.
The central office equipment must provide an interface for the call center software platform.
Aggregation Node Equipment:
High upstream optical fiber transmission capacity, capable of transmitting 2 line-rate 1000M Ethernet channels and 10 E1 bandwidths, providing 2 mutually backup uplink interfaces.
Downstream, capable of decomposing into no more than 10 low-speed optical fiber interfaces (ensuring each optical port receives 2 line-rate 100M bandwidths), facilitating longer distance transmission over single-core fiber, up to 80KM.
All optical interfaces adopt SFP interfaces for easy replacement based on distance and other environmental factors.
Has management functions for each remote device.
Township/Street Communication Access Equipment:
Supports dual-fiber mutual backup; optical fiber transmission bandwidth 2.5G.
Up to 24 groups of E1, or provides 30 telephone/audio monitoring channels, trunking micro base station access, and other services.
2 physically isolated line-rate 1000M Ethernet ports, totaling 2000M.
4 physically isolated line-rate 100M Ethernet ports, totaling 400M.
Provides a standard SNMP network management interface.
User Access Terminal Equipment:
Provides 2 mutually backup SFP optical fiber interfaces.
Provides two groups of physically isolated Ethernet channels, with a total bandwidth of 200M. 4 interfaces, where interfaces 1, 2, and 3 share 1 line-rate 100M Ethernet, capable of VLAN isolation; the 4th Ethernet group is a physically isolated, dedicated 100M bandwidth Ethernet.
Capable of outputting 2 telephone lines, one audio EM 2/4-wire with adjustable gain (for connecting to radio base stations or for audio monitoring), and one RS422/RS485 interface.
V. Communication Transmission Equipment
Leased dark fiber.
User-Side Equipment
| Equipment Name / Administrative Region | Quantity | Unit Price | Total | Remarks |
Central Office Equipment at Municipal Information Center | IDM G3CP Main Chassis | 2 | | # | Each chassis can accommodate up to 8 2.5G access cards |
Power Supply Module | 4 | | # | Dual power supply redundancy |
ODXC Card | 4 | | # | Cross-connects all services within the entire chassis |
NMS Card | 2 | | # | Connected to NMS computer |
2.5G-USER CardA | 7 | | # | Connected to IDM GP-MPconv, up to 4 units can be connected, 2 units recommended |
2.5G-USER Card B | 7 | | # | Connected to IDM OMP3500, can connect 1 unit |
WG Dispatch Panel | 1 | | # | Provides remote telephone dispatch and external line access, and can connect to the dispatch server and dispatch console |
16E1DXC Card | 1 | | # | Aggregates multiple user optical port telephones |
IP Softswitch Gateway Card | 1 | | # | Provides conversion from external or internal telephone lines to IP softphone calls |
Voice FXO | 2 | | # | Provides 30 external line telephone interfaces |
42*E1 Card | 2 | | # | Used for interconnection between devices, or to provide backup E1 channels |
Equipment Cabinet | 1 |
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| Distribution Cabinet | 1 |
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| Cabinet and Distribution System |
Township/Street | IDM OMP3500 | 7 | | # | High-bandwidth access device for township/street offices, providing 6 groups of physically isolated Ethernet ports with a total bandwidth of 2400M |
Township/Street | IDM GP-MPCONV | 14 | | # | Intermediate node fiber access device with bandwidth adjustment and allocation functions |
Township/Street | Equipment & Distribution Cabinet |
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Grassroots Grid Access | IDM NTD421 | 80 | | # | Grassroots access device, providing 2 groups of physically isolated Ethernet and telephone/audio access, with a total bandwidth of 250M |
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- User Equipment
No. | Equipment | Qty | Unit Price | Remarks |
1 | Portal Website Computer | 1 |
| External Network Publicity and Reporting |
2 | Intranet Computer | 1 |
| Information Collection and Query |
3 | Network Camera | 1 |
| Service Quality Monitoring and Security Surveillance |
4 | Monitoring Pickup | 1 |
| Ambient sound detection, service quality detection |
5 | Loudspeaker | 1 |
| Public address broadcasting, remote command, video conferencing |
6 | Telephone | 1 |
| Used for business communication and dispatch communication; the government can no longer subsidize telephone expenses |
7 | Wireless Trunking Repeater Walkie-Talkie | 1 |
| Standard walkie-talkie connected to communication equipment enables trunking micro-power repeater (option) |
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