New technology promises to do more with less spectrum

A new technology that is part of the next generation of LTE could help wireless carriers more than double the speed of their networks and make the most out of their limited spectrum holdings. Each spectrum band, be it PCS, AWS or 700 MHz, is subdivided into smaller chunks of paired and unpaired spectrum that are used by carriers to deliver wireless services. It is the size of these chunks, ranging in some cases from a single 5 MHz channel to paired 20 MHz channels, which determines the speed of a wireless connection. Yet those stuck with limited amounts of spectrum or unsuitably small chunks of desirable bands can look to a new technology called carrier aggregation — part of the LTE-Advanced standard — to help them deliver speeds faster than current LTE connection. “If they have a lot of fragmentation, it's a way of defragmenting the spectrum and using it in a combined manner,” Alex Pavlovic, director of technology at Nordicity, said in a phone interview. The technology can enable wireless carriers to bring together different narrow spectrum channels of differing sizes from different bands and treat them as a single broad channel, balancing out the relative importance of the different channels and offering double the speed of traditional LTE. International wireless industry group 3GPP first introduced the idea of carrier aggregation in September 2011 as part of its LTE-Advanced standard for connectivity that goes beyond the LTE standard developed in March 2009. “It allows you to combine frequencies within the band, or combine frequencies in separate bands,” Pavlovic said. “Operators are looking at this two ways, from getting multiple licences in one spectrum band and combining them together or using different bands, say 700 MHz and 2500 MHz, and using them in a combined manner.” Under the most widespread implementations of LTE in North America, download speeds max out at 150 Mbps under perfect conditions, while the current maximum with carrier aggregation and other LTE-Advanced technologies sends the limit to 450 Mbps, with even faster speeds on the horizon. Every spectrum band has trade-offs between speed and coverage, with lower frequencies meaning better coverage while higher frequencies mean better speed. The government’s 700 MHz auction, for which the results were announced in February, raised more than $5.27 billion in part because the band, according to Pavlovic, splits the difference between speed and range. Yet the upcoming auction for AWS-3, paired spectrum in two slices between 1755 and 1780 MHz and 2155 and 2180 MHz, offers wireless carriers more bandwidth for delivering mobile data such as the mobile video content from the NHL on which Rogers Communications Inc. has made a $5.2-billion bet. “It can bridge the gap between high-frequency, high-bandwidth spectrum with less coverage and low-frequency spectrum that penetrates buildings and has better coverage,” Pavlovic said. Stuart Jack, another technology analyst at Nordicity, said the increased speeds from carrier aggregation, which can turn a 5 MHz channel into a 40 MHz two-way channel or more, is increasingly important now that mobile data has become the major source of traffic on mobile networks. “Every new device has new capabilities that encourage even wider data use,” he said in a phone interview. “There seems to be no end to the demand curve, but they're not making spectrum. They're not making land and they're not making new spectrum.” Pavlovic said in order to take advantage of spectrum-aggregation technologies, wireless carriers must upgrade their networks and users must have compatible devices. The only current smartphone that supports carrier aggregation is Samsung Electronics Co.'s Galaxy S5, although Pavlovic said the next version of Apple Inc.’s iPhone, which he expects to be revealed in the coming weeks, will likely be compatible as well. South Korean carrier SK Telecom announced a commercial deployment of spectrum aggregation in January, which it said in a press release was the first-ever use of such technology. In March, AT&T became the first wireless carrier in the United States to use carrier aggregation, using 700 MHz and 2100 MHz spectrum to offer LTE-Advanced connections in Chicago, according to a news release at the time. In June, Sprint Corp. said its Spark service, which aggregates spectrum on the 800 MHz, 1900 MHz and 2500 MHz bands, was active in 24 communities in the United States and the company has said it plans to deploy it in 100 more cities by the end of 2016. Dragan Nerandzic, chief technology officer at Ericsson Canada, said in a phone interview the technology is “definitely on the roadmap of every operator that has deployed LTE,” because of its “more efficient use of spectrum.” However, he said some carriers with the best spectrum channel will hold off on adoption because, even with increased data usage, there is not a pressing need for aggregation. “Those that have the luxury of having a contiguous amount of spectrum for LTE, they probably are not in a great level or urgency,” he said. “But those who have to deal with fragmented spectrum, they can also accomplish similar effects by proceeding with aggregation.” Requests to Rogers, BCE Inc. and Telus Corp. for information on plans to adopt carrier aggregation were not returned at press time. Pavlovic said carrier aggregation could gain popularity in Canada because of the government’s apparent willingness to use its control of spectrum licences as a means for policy. “Government is obviously imposing spectrum limits when it comes to obtaining new licences,” he said, adding that the government wants the spectrum to be used for its “highest economic-use principle.” Jack added that, once carrier aggregation becomes a widespread technique for managing spectrum usage, the government’s metrics for competition and telecom regulation could change. “When you think of aggregation, really you're changing the technical and, therefore, the economic basis for the use of spectrum,” he said. — With reporting by Peter Henderson at phenderson@thewirereport.ca and editing by Derek Abma at dabma@thewirereport.ca

New technology promises to do more with less spectrum

News | August 27, 2014

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