Delivering breaking news with cellular uplinks
Broadcasters have always faced the problem of getting the story, especially live reports, back to the newsroom. Originally, film or tape was couriered back to base, a system that had great capacity but long latency. Microwave and satellite have been the mainstay of news operations over recent decades, with microwave being useful when there is a clear line of sight back to a receiving point, and primarily found in metropolitan areas. Satellite can be used almost anywhere. Fiber can also be an option if there is a handy access point.
In a world of citizen journalists, the public has come to expect breaking news within seconds, not the hour or more it may take to get a DSNG truck to the scene. Since the roll-out of 3G services and the popularity of the smartphone, it is rare for a news event to happen without members of the public capturing video clips of the scene on their phones. Although the camera technique and the video quality may be poor, the clips have the gritty reality and immediacy that looks good in a newscast. The first reporters at a scene soon adopted the cellphone as a way to capture news as it happened.
Now that cellular operators are migrating to 4G LTE networks, there is the opportunity to send back higher-quality video by utilizing the higher upload speeds available with 4G.
The concept of video-over-cellular has transformed the way broadcasters can respond to events and get breaking news to air before the satellite or microwave truck reaches the scene. A reporter on a motorbike with a suitably equipped backpack can reach a scene in a fraction of the time of a truck, and at a lower cost.
However, a single cellular connection, especially 3G, rarely delivers satisfactory video quality. The secret to using the cellular network is to aggregate a number of separate cellular modems, and spread the packetized video data over the different connections. The receiver back at the newsroom assembles all the packets back into sequence to recover the compressed video stream. The modems can operate with different cellular network providers if available, providing additional diversity.
Cellular uplink options
Figure 1. There are several wireless IP connections that can be aggregated to uplink live or stored news stories.
There is a catch: Any major news event will see congestion in the cellular networks as the public sends pictures to social networks, so the available bandwidth may be limited and unreliable. But, there are alternates. The cellular network can be supplemented with Wi-Fi, WiMAX and BGAN if they are available, bonding all the IP pipes together to aggregate available bandwidth, as shown in Figure 1.
- WiMAX metro net. WiMAX (Worldwide Interoperability for Microwave Access) provides last-mile access to the Internet through a wireless metropolitan area network (WirelessMAN). It is based upon the IEEE 802.16 broadband wireless access standard. The networks use a cell size of 3km to 10km and use the 2.3GHz, 2.5GHz and 3.5GHz frequency bands. The 700MHz and 1.8GHz bands are also under consideration. The service provides access speeds from 1Mb/s to 5Mb/s per user. WiMAX is available in many metropolitan areas across 149 countries.
- BGAN broadband satellite. BGAN is a satellite broadband network operated by Inmarsat. The ground station uses a laptop-sized antenna and is popular for newsgathering in remote places where there is no cellular coverage. The data rate is limited by the small size of the antenna, and typically achieves only 500kb/s. It does have the advantage that it can be used when cellular coverage is challenged by congestion. However, given the choice, cellular connections are much less costly than a BGAN service.
All the different carrier standards have roadmaps that will increase bandwidths over time, so the delivered video quality should improve further in future years.
- Store and forward. So, what if the cell is congested, there is no WiMAX, and BGAN is not an option? Many cities have Wi-Fi hotspots, and there are Internet cafés and coffee shops — Wi-Fi is everywhere. If the uplink is in a Wi-Fi zone, that can be used. If not, the alternative to a live broadcast is to store a clip, and forward it as soon as possible via FTP over whatever Internet connection is available.
Many reporters will want to edit their material and just send back short clips to the newsroom. A good bonded-cellular product should support a round trip to a laptop NLE and back so that the reporter can prep his/her material.
- Using another cell. When a live insert is essential and the cell is very busy, another option for live broadcasts is to supplement the bonded-cellular transmitter with an extender in an adjacent cell. One vendor at the 2013 NAB Show was showing an extender that links via license-free Wi-Fi technology. The extender can be up to 300m away from the reporter’s terminal and provides further diversity transmission for the backhaul. In urban areas where picocells are used, this can be far enough away from any crowds near the reporter that may be also using their phones and
- Antenna. There are several ways to implement bonded cellular. The simple way is to use off-the-shelf USB modems (3G/4G dongles). However, just like cellphones, the RF design of a dongle is sub-optimal. Small size and styling will compromise the efficiency of the antenna. Using several dongles in close proximity will also degrade performance. For the best results, a product that uses a properly designed antenna will give better performance.
3GPP and acronyms
The cellular world has just as many acronyms as broadcast technology. Many of these stem from the 3rd-Generation Partnership Project (3GPP). 3GPP is working on technologies beyond Long-Term Evolution (LTE), including LTE advanced (LTE-A). One big change is the move from circuit switching (like a telephone call) to packet switching with the General Packet Radio Service (GPRS), which was introduced with 2G to carry data, and Universal Mobile Telecommunications System (UMTS), a generic term for 3G technologies. UMTS emulates circuit switching for real-time data like voice and packet switching for general data.
Release 6 of 3GPP introduced high-speed downlink packet access (HSDPA). Combined with the high-speed uplink, this gives high-speed packet access (HSPA).
Release 7 of 3GPP evolved HPSA to HSPA+ with faster download speeds (typically 20Mb/s). This was a step on the way to 4G technologies with a target of 100Mb/s download.
LTE is an intermediate step to 4G, but marketing folks at cellular networks have highjacked the term “4G” to encompass the LTE features in release 8 of 3GPP. The theoretical maximum upload speed in an LTE network is 170Mb/s. LTE uses MIMO, (multiple receive and transmit antennas) to improve performance. LTE supports speeds up to 500km/s.
True 4G awaits LTE advanced (LTE-A) and promises downloads up to 3Gb/s and upload to 1.5Gb/s, plus improved spectral efficiency.
To the reporter, LTE (“4G”) offers lower latency and higher bandwidths than 3G, and provides a better carrier for news backhaul. Unfortunately, 4G is not available universally, so any cellular bonding system must be able to take advantage of 3G and LTE. As more spectrum is freed for mobile application, 4G coverage can only increase.
Keep the DSNG truck
One major advantage of the use of reporter backpacks and cellular bonding is that costs go down.
But the DSNG truck is manned by broadcast engineers; they can set up the satellite circuits and manage the live broadcast. The lone reporter with a backpack is not an engineer; so one important aspect in the selection of a video uplink system is the user interface. The reporter needs it to be almost as simple as using a cellphone. Adapting between expensive BGAN and cheaper cellular operator should all be handled by the product, not by the reporter. It should be simple to operate live, or in store-and-forward mode for later transmission.
Cellular bonding, whether a backpack or a Mi-Fi wireless router adding a second connection to a cellphone, is not a replacement for the SNG or microwave truck. It is another option for the news broadcaster. It allows the broadcaster to cover stories that may not have been possible in the past for logistic or financial reasons. It allows early responders to start broadcasting as soon as they reach the scene. In a world of 24-hour news channels, it gives the broadcaster more options to cover more stories. As 4G rolls out, it becomes a more viable option to complement DSNG vehicles.
—David Austerberry, editor
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