IV. System Application Requirements

Ø  Dual-channel wireless is required, one channel for transmitting control signals an¶d the other for transmitting video signals;

Ø  Control data and video data should not conflict with each other or seize bandwidth  resources;

Ø  The field strength of control signal at each point in the covered area shou∞ld be ≥-65dB, with a packet loss rate of ≤5‰ and a delay of < 100ms;

Ø  A wireless average bandwidth of ≥ 20M is required for video signal, so as to suppo₩rt the simultaneous transmission of 8 channels of 720P video;

Ø  The wireless roaming time of video signal and control signal should be ≤ 50ms;↕

Ø  Since the field wireless environment is complex, the equipment should have solid anti-♥interference ability;

Ø  On-site outdoor installation requires wireless AP to have good sei smic resistance and IP67 protection level;

VI. Solution

In this solution, a Hirschmann layer-3 switch GRS1042 is deploye‌d in 1# coal tower for video transmission, so as to  realize the connection with H3C switches of 2# coal tower and coke oven control ¶center, and an H3C switch is deployed for transmission of control signals;

According to the investigation of the site environment, the site is divided into three area's: coke pusher area, coke guide area and tram area. To this end, hierarchλical design is applied to solve the site occlusion. 4 wireless A₹Ps are deployed along the tram track in the tram area, which are covered by Hirschmann§ directional antenna; since the coke guide area is relatively open, 1# coal to×wer, 1# end platform, 2# coal tower, 2# end platform and intermediate Overhaul access a♥re covered by Hirschmann omnidirectional antenna; 4 wireless APs are  deployed along the coke pusher track in the coke pushing area, which are covered by Hi♣rschmann  directional antenna. All AP points are laid with 8-core optical fib→ers to connect with 1# coal tower, so as to lay a foundation πfor dual channels.

All Hirschmann wireless devices are equipped with 'dual channels, namely, two groups of WLAN and two groups of LAN ports. Thro×ugh reasonable configuration, WLAN1 of the wireless device, corresponding ±to the LAN1 port, transmits control signals to the H3C switch of 1# coal towδer; WLAN2 of wireless device, corresponding to the LAN2 port, transmits video signals to the Hi≈rschmann GRS1042 switch of 1# coal tower, and the Hirschmann switch is subjected to a seπries of optimized configurations to communicate with t←he coke oven control center. Through the QoS of wireless AP and switch, cont rol data and video data will not seize the same limited bandwidth resources.

u     VIII. Project Acceptance Test 

During the project acceptance stage, Hirschmann's wireless transmission is stab le with a performance beyond the user's expectation, getting ahead of other proje☆cts in the industry and reaching top level of the industry. In this project, €the packet loss rate of control signal is < 2‰, and the te∏sted average wireless bandwidth of video signal transmission is 30M.