Communication Network Design in Grid Management

I. Comparison of Communication Technologies

Currently, management across various government departments is largely grid-based, and grid communication typically requires two physically isolated networks: a government industry private network and a portal website, sometimes also including surveillance networks, video conference networks, etc. Some of these networks have high confidentiality requirements, and physical isolation between networks is mandated, especially in sectors with strict confidentiality needs such as the military and public security, where VLAN isolation between networks is strictly prohibited.

At present, most grid management communication methods rely on public 3G/4G mobile networks, leased broadband networks, and similar means. Even with additional confidentiality measures, the level of security achieved is not high. Some use leased E1 link private networks, which can meet confidentiality requirements, but the transmission bandwidth is limited, particularly insufficient for supporting more video transmission needs. Additionally, the rental cost of E1 links is relatively high.

Therefore, grid management communication typically employs leased dark fiber. Currently, 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 need to be implemented over fiber, along with dispatch telephones, audio monitoring for service quality, and in some cases, wireless trunking forwarding within the grid.

Three types of equipment can typically accomplish remote communication over dark fiber. Given the large number of remote terminals, expensive SDH and OTN equipment are not considered here; only Media Converters, PON, and TDM multiplexing technologies (PDH+PCM) are considered. A comparison of these three technologies is provided below.

	Media Converter	PON	TDM（PDH+PCM）Optical Transmission
1. Types of Transmission Services	Only1 Ethernet	Has1 Ethernet, telephone, and serial port	Can have multiple line-rate Fast Ethernet or line-rate Gigabit Ethernet ports, multiple telephone and serial ports,E1, etc.
2. Transmission Technology	Packet Switching	Packet Switching and Softswitch	TDM Time-Division Transmission
3. Isolation Technology	VLAN Virtual Isolation	VLAN Virtual Isolation	Time-division physical isolation provides better isolation performance
4. Confidentiality	Low — any media converter can interoperate. If VLAN isolation is used, not only is bandwidth reduced, but all unused packets are delivered to the port, making them vulnerable to decryption.	Medium — with VLAN isolation, not only is bandwidth reduced, but all unused packets are delivered to the port, making them vulnerable to decryption.	High — isolated channels independently occupy dedicated bandwidth, with wire-speed network bandwidth unchanged. Only useful information packets are transmitted to the user port.
5. Technical Complexity	Low	High	Medium
6. Transmission Distance	Long	Short	Long
7. Telephone Dispatch Technology	Soft dispatch, high latency	Soft dispatch, high latency	Supports dispatch via both TDMswitching and softswitch technologies, with low latency
8. Number of optical fibers required to achieve 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 exceeds 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 without guarantee	Large transmission delay without guarantee	Small and fixed transmission delay

In PON, since the transmission bandwidth exceeds 1G, the optical module transmission distance (which decreases as bandwidth increases) is relatively short. Combined with the optical splitting loss introduced by ODN optical splitters, the optical attenuation increases and the transmission distance is further significantly reduced. Moreover, the uplink bandwidth is generally small, making PON networks unsuitable for fiber transmission in video surveillance applications.

II. Multi-Channel Transmission System with Dedicated Uplink/Downlink Transmission Bandwidth

TDM-based optical transmission offers significant advantages when telephone, voice monitoring, and wireless trunking micro-base station forwarding services are required.

PDH and PCM technologies in TDM optical transmission are among the earliest communication technologies and are highly mature. With the addition of multiple line-rate Fast Ethernet and Gigabit Ethernet channel transmission capabilities to PDH, these technologies have gained renewed vitality.

Raytrans' TDM-based optical transmission technology includes central office equipment, aggregation node equipment, and terminal equipment, sharing the same topology structure as PON networks. It is the optimal alternative to PON networks in video surveillance environments and long-distance transmission scenarios.

The Raytrans TDM transmission system includes central office equipment IDM G3CP, aggregation node equipment IDM GP-MPconv, and remote user access equipment IDM NTD421.

On the fiber link from the central office to the aggregation node, the fiber transmission bandwidth is 2.5G, capable of carrying two groups of physically isolated Gigabit line-rate Ethernet channels and dozens of E1 channels.

The fiber transmission bandwidth from the aggregation node to the remote end is 250M, capable of carrying two groups of line-rate Fast Ethernet channels and several E1 channels. E1 channels are typically used for narrowband services such as telephone, voice, and serial data transmission. Currently, up to 2 telephone lines, one gain-adjustable audio EM2/4-wire interface (for connecting radio base stations or for audio monitoring), and one RS422/RS485 interface can be provided.

The optical fiber transmission bandwidth from the aggregation point to the remote end is relatively low, which helps increase the transmission distance.

The central office equipment IDM G3CP is not only a transmission device, but also has rich PCM access functions, as well as powerful information switching and aggregation capabilities:

1. It can aggregate all broadband Ethernet services;

2. It can perform non-blocking cross-connection for all remote 64K (or N*64K) services, with a cross-connection capacity of 128E1*128E1;

3. It can aggregate all remote serial ports via Ethernet interfaces, i.e., functioning as a serial port server;

4. It can switch remote telephone services, i.e., functioning as a built-in telephone exchange;

5. It can dispatch remote telephones, voice, and video, satisfying the functions of multimedia dispatch communications, and can also integrate SMS sending and fax sending/receiving functions;

6. It can provide access to 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 telephones and wireless trunking;

7. It can connect to dispatch consoles, supporting up to 250 dispatch consoles for joint control. Meanwhile, the dispatch console software integrates GIS geographic information system software, enabling comprehensive dispatch of wired, wireless, voice, data, video, and location information.

III. Dispatch Center Dispatch Console Functions:

1. The map design is mainly targeted at XX City.

2. Click "GIS" to open the interface as shown below:

1. The interface is divided into two parts: the location list on the far left and the XX City map on the right.

2. The map image can be zoomed in and out within a certain range. The clickable range for annotations needs to be configured to an acceptable area.

3. First, mark the locations on the map (the annotations can be created by the user; currently, the marked locations correspond to those in the list on the left). Then click a location name in Table 1, such as "Tuanhe Street," and the map will display the annotation for that location.

4. Click the annotation to select operation functions (phone, video, monitoring).

To make a call, first lift the handset, then click the "Phone" button to initiate the call.

To view the video of that location, click the "Video" button, and a small video window will pop up, as shown below:

Monitoring can also be implemented. Speakers and pickups are installed at the location. By adding the speakers and the dispatch console handset to the same conference room, monitoring can be achieved. Conference rooms can be selected (e.g., the left speaker and right speaker can be in different conference rooms). Click the "Monitor" button to pop up the selection window.

Simply select the target to be monitored.

IV. Communication Equipment Room and Command Center Configuration in Grid-Based Management:

The communication equipment room must meet the physical isolation requirements between the government portal website and the government intranet, and must also provide interfaces for dispatch telephones, public network telephones, SMS, and fax.

Communication Equipment Room Equipment:

No.	Equipment	Qty	Unit Price	Total	Remarks
1	Firewall	1			Run the firewall system; all remote users connect to the external network through this firewall.
2	Public Opinion Monitoring Server	1			Internet Behavior Management and Public Opinion Management Software Platform
3	Multi-port router	1			Provides broadband access to multiple carriers, reducing the probability of network failures
4	Portal server	1			External publicity
5	Government cloud processing server	1			Cloud storage, cloud computing
6	Intranet Web Server	1			OA System and Grid Software Operating Platform
7	Voice Dispatch Communication Server	1
8	Call Center Server	1
9	Internal/External Network Security Gateway	1			Used for data switching between the internal and external networks
10	Database software	1
11	Related software development	1

Load balancing devices are not considered for the time being. As business volume grows, two load balancing devices can be deployed at a later stage to provide load balancing for all application systems. At the same time, the two devices can form an HA pair with each other, so that if one load balancing device fails, the other can continue to operate, thereby ensuring normal system operation.

Two WEB servers can also be deployed, both installed with LINUX systems, connected to the load balancing system at the front end. On the one hand, this can reduce the load on the primary server; on the other hand, if one server fails, the other can continue to operate.

Disaster recovery backup mirror servers can also be added at a later stage: two servers can be deployed in a telecom or mobile IDC to perform remote backup of system data and programs, ready to be activated in the event of an unexpected interruption of the primary system, serving as an emergency replacement for the main platform system.

The command center is used for displaying information from user-side video surveillance, audio monitoring, dispatch telephones, the portal website, the intranet, and for big data processing, etc.

The main configuration of the command center is as follows:

No.	Equipment	Qty	Unit Price	Total	Remarks
1	Audio Mixing Console	1
2	IPVideo Decoding Matrix	1
3	VGAvideo switching matrix	1
4	Large-screen video wall splicing server	1
5	Video wall	N*M
6	Speaker	2
7	Microphone	N
8	Printer	1
9	SMS Gateway	1
10	Custom control console with telephone	N
11	Console computer	N units
12	Intelligent Lighting Control System	1
13	Fresh Air System Controller

No.	Equipment	Qty	Unit Price	Total	Remarks
1	Multimedia dispatch software	1
2	Call Center Software	1

Central Office Equipment:

1. It shall provide SDH interfaces STM-1 and STM-4, enabling connection to the carrier's SDH optical fiber communication network for interconnection with higher-level authorities or other business units within the city;

2. It shall provide 200M bandwidth (2 wire-speed 100M) optical fiber interfaces to each node, along with telephone and voice services. To minimize the number of optical fibers, the fiber to township/street offices shall 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 transmission distance of 80KM for extended reach) shall be used to connect to administrative villages.

3. The central office equipment shall integrate dispatching functions to enable scheduling of communication resources within the remote grid, namely:

Basic functions: call, call transfer, call forwarding, call park, answer, call pickup, hold/resume, do-not-disturb setting, and other operations.

Dispatch Functions: Forced insertion, forced release, call takeover, monitoring, call barring, manual/automatic transfer, group call, group paging, conferencing, dynamic grouping, hierarchical collaborative dispatch, and other operations.

Broadcast Functions: Broadcast, loudspeaker announcement, environmental monitoring, and other functions. Broadcast includes instant broadcast and scheduled broadcast; broadcast audio sources can be selected from internal audio files, external audio sources, or TTS files for playback.

Trunking Intercom: Capable of dispatching intercom radios of different frequency bands, different models, and different standards (digital/analog); push-to-talk (PTT) control can be performed through the dispatch software interface.

Conference Functions: Conference setup, conference scheduling, conference member identity authentication, multiple simultaneous conferences, conference process monitoring, and other operations.

4. The provided dispatch software must be capable of integrating with GIS geographic information systems and synchronized surveillance video recording;

5. The central office equipment must provide an interface for the call center software platform.

Aggregation Node Equipment:

1. Large upstream optical fiber transmission capacity, capable of transmitting 2 wire-speed 1000M Ethernet channels and 10 E1 bandwidths, providing 2 mutually redundant uplink interfaces;

2. Downstream capability to split into no more than 10 low-speed optical fiber interfaces (ensuring each optical port receives 2 wire-speed 100M bandwidth), facilitating longer transmission distances over single-core fiber, up to 80KM;

3. All optical interfaces adopt SFP interfaces for easy replacement based on distance and other environmental conditions;

4. Management functionality for each remote device.

Township/Street Communication Access Equipment:

1. Supports dual-fiber mutual redundancy; optical fiber transmission bandwidth of 2.5G;

2. Up to 24 groups of E1, or provides 30 telephone lines or audio monitoring, trunking micro base station access, and other services;

3. 2 physically isolated wire-speed 1000M Ethernet channels, totaling 2000M;

4. 4 physically isolated wire-speed 100M Ethernet channels, totaling 400M;

5. Provides standard SNMP network management interface.

User Access Terminal Equipment:

1. Provides 2 mutually redundant SFP optical fiber interfaces;

2. Provides two groups of physically isolated Ethernet channels with a total bandwidth of 200M. 4 interfaces, where interfaces 1, 2, and 3 share one wire-speed 100M Ethernet and can be isolated via VLAN partitioning; the 4th Ethernet group is a physically isolated dedicated 100M bandwidth Ethernet.

Capable of providing 2 telephone lines, one audio EM2/4-wire interface with adjustable gain (for connecting 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 Unit	4		#	Dual power supply redundancy
	ODXC Unit	4		#	Cross-connects all services within the entire chassis
	Network Management Unit	2		#	Connected to NMS computer
	2.5G-USER Unit A	7		#	Connected to IDM GP-MPconv, up to 4 units can be connected, 2 units recommended
	2.5G-USER Unit B	7		#	Connected to IDM OMP3500, can connect 1 unit
	WG Switching Unit	1		#	Provides remote telephone dispatch and external line access, and can connect to the dispatch server and dispatch console
	16E1DXC Unit	1		#	Aggregates multiple user optical port telephones
	IP Softswitch Gateway Unit	1		#	Provides conversion from external or internal telephone lines to IP softphone calls
	FXO Voice Unit	2		#	Provides 30 external line telephone interfaces
	42*E1 Unit	2		#	Used for interconnection between devices, or to provide backup E1 channels
	Equipment Cabinet	1
	Distribution Cabinet	1			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
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
				#

6. User Equipment

No.	Equipment	Quantity	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 no longer needs to subsidize telephone charges
7	Wireless Trunking Relay Walkie-Talkie	1		Ordinary walkie-talkies connected to the communication equipment can achieve trunked micro-power relay (optional)