Making mobile network more compertitive


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Making mobile network more compertitive

  1. 1. Solution JUN 2010 . ISSUE 5639 Making mobile networks more competitive Despite the rapid growth of broadband data services, most mobile operators, especially 3G operators, are struggling to make profits. Traffic is heavier and low-value subscribers are using most of the bandwidth. How to balance the load to ensure bandwidth availability for high-value subscribers is a tough issue for mobile operators. Overlapping of 3G/2G+WiMAX networks verlapping 3G/2G+WiMAX networks has proven to be one effective solution. In an area without 3G coverage, distributed WiMAX base stations can be deployed to meet subscriber requirements for basic broadband services. When higher system capacity and data rates are required, subscribers’ bandwidth requirements can be met by raising the density of WiMAX distributed base station sites or by using multi-carrier solutions or other expansion methods. In a 3G coverage area, the 3G network is mainly responsible for meeting high- value subscriber requirements for basic mobile broadband services. To meet the high bandwidth requirements of low- value home or PC subscribers, distributed WiMAX base stations can be deployed to achieve continuous coverage in an area, offloading the high throughput of low- value subscribers from the 3G network. For the requirements for high By Lai Guoting & Xiao Xiao Making mobile networks more competitive bandwidth and capacity at hotspots in urban areas covered by 3G/2G networks, continuous coverage in a cluster should be carried out at the early stage. At middle and later stages, the clusters should be concatenated for continuous coverage of a larger area, depending on investment and operation needs. To eliminate blind spots in macro network coverage or cope with difficulty in site acquisition in some areas, compact base stations can be directly mounted on poles or in other locations. In some indoor scenarios such as cafes and large exhibition halls, indoor micro base stations can be deployed to enhance indoor coverage and meet requirements for large capacity and high quality. Clearwire in the U.S.A. has successfully commercialized a WiMAX network using this kind of network construction. In some dense urban areas there, sites are tough to come by, but electrical and other poles are plentiful. When distributed base stations have been deployed to meet coverage requirements in most areas, compact base stations are mounted on outdoor poles as a low-cost solution to quickly cover blind spots and improve the QoE. Leveraging WiMAX advantages to be more competitive In addition to effectively addressing the needs of mobile operators for developing wireless broadband services, the overlapping of 3G/2G+WiMAX networks benefits operators in other ways. Some new technical features and networking models of WiMAX help improve spectral efficiency and raise network coverage for better network quality and QoE. All this strengthens a mobile operator’s core competitiveness and ensures sustainable profitability. Using new technologies for better network coverage Currently, WiMAX network coverage is mainly restricted by uplink (UL) coverage. Enhancing UL coverage performance has become a major concern throughout the industry. Performance needs to be improved by taking into account UL O Fig. 1 Comparison between coverage capability improvements arising from different UL technologies Fig. 2 Comparison between average sector carrier throughput increases (DL/UL) driven by different new features Link budget gain(dB) Coverage improvement UL ICIC DL BFUL IRC UL 64QAMUL MIMO UL CSMUL MLD UL MIMO UL FFR 3.5 3 2.5 2 1.5 1 0.5 0 25% 20% 15% 10% 5% 0% 60% 50% 40% 30% 20% 10% 0%
  2. 2. Huawei Communicate JUN 2010 . ISSUE 56 40 features should be applied in different scenarios. In dense urban areas, MIMO BF can enhance received signal strength and reduce interference between sector carriers by using weighted beamforming transmission on common MIMO antennas and considerably improve QoE for edge subscribers. In general, 4T4R BF helps increase the throughput of DL sector carriers by 15% on average and the DL edge subscriber rate by around 25%. By using different one-third frequencies between adjacent UL sites, UL FFR helps avoid inter-frequency interference between adjacent base stations. While decreasing interference and increasing the carrier-to- interference and noise ratio (CINR), it boosts the usage of the high-order modulation coding scheme (MCS), raising the average UL sector throughput and link efficiency. In the same bandwidth-to-subframe ratio, UL FFR can improve the sector carrier throughput by around 50% over UL PUSC 1/3; it can also improve spectral efficiency by some 35% over partially used sub-carrier with all subchannel (PUSC ALL). Fig. 2 shows a rough comparison between sector carrier throughput increases driven by various new features. Currently, Huawei’s base station series supports the commercialization of these features. New networking models for better spectral efficiency As most WiMAX operators are short of frequency spectrums, they usually use the 20 to 30MHz band at a frequency bandwidth of 10MHz. Intel announced that it would only embed 10Mbps Intel chips in laptops and combine the chips with Wi-Fi to meet the requirements of different nomadic PC customers for broadband data services. Both CPEs and USB dongles support the 10MHz bandwidth, while a small number of terminals support 5MHz, 7MHz and other bandwidths. Due to protocols and bandwidth restrictions, the 5MHz bandwidth is not robust enough to support FFR networking. From the perspective of terminals, chips, FFR, and multi-carrier expansion, the 10MHz bandwidth is ideal for WiMAX networking. The bandwidth of 10MHz only makes 2 to 3 frequencies available for the operator. Keeping its network competitive now and in the future with such a scarcity of frequency resources is a serious challenge for an operator. With a 30MHz spectrum at a frequency bandwidth of 10MHz, Huawei believes that the PUSC ALL 1×3×3 networking model can satisfy both coverage and capacity requirements. Suppose that an operator holds a 20MHz or 20MHz+ spectrum with a frequency bandwidth of 10MHz. Given the great interference of the two frequencies under PUSC with ALL, the resources are not enough to achieve continuous coverage. If FFR is used, each sector edge uses only one third of the bandwidth of each frequency and co-channel interference to subscribers on the sector edge can be greatly reduced with coverage maintained. Additionally, all spectrum resources of this frequency can be used in an area with little interference, and address high-capacity needs of broadband data services. This means that the FFR 2×3×2 networking model can be used at the early stage. The mid-stage expansion can then be carried out by using dual-carrier overlapping technology, such as the S222 FFR 1×3×1 networking model. Using UL IRC, UL MIMO and other technologies enhances UL interference suppression capability. With dual-carrier expansion, the later-stage expansion can be done by replacing the FFR 1×3×1 networking model for the second carrier with PUSC with ALL 1×3×1. Various new technologies and networking solutions can then be combined to raise overall network capacity and guarantee the sustainable competitiveness of the whole network. Operators can use Huawei base stations, including distributed WiMAX base stations, compact base stations, and micro base stations, to establish a continuous three-dimensional and multi- layered broadband network that meets the hybrid networking requirements of 3G/2G operators. To effectively boost profitability, they can employ new WiMAX features and networking models to improve mobile network coverage and guarantee the QoE for mobile broadband users. interference suppression and UL gain. UL interference can be suppressed by using the latest technologies such as inter- cell interference coordination (ICIC) and UL interference rejection combining (UL IRC). UL ICIC suppresses inter-frequency interference between adjacent UL base stations through frequency misalignment on the edge of their sectors. With this technology, the UL interference suppression gains about 2dB, and the coverage radius of a single base station increases by around 15%. As for UL IRC, it maximizes interference suppression by rejecting interference sources in reception combining. It can achieve around 2dB in UL interference suppression gain, increasing the coverage radius of a single base station by 15%. UL MIMO is a new technology for raising UL gain. As a basic feature of Wave2, UL MIMO A is similar to DL MIMO A and helps obtain a UL gain of 3 to 4 dB, equivalent to raising the coverage radius of a single base station by around 20%. Although specific principles underlying each new technology vary, statistics show that they produce similar effects in performance improvement. Fig. 1 shows a comparison between the coverage capability improvements. Huawei is the first vendor that has employed these enhancement technologies to improve the coverage performance of a commercial network. Applying new features to increase network capacity One of the key points to guarantee QoE for broadband data services is to improve DL/UL sector carrier throughput and QoE for edge subscribers in particular. For the fixed line model, the improvement of sector carrier throughput can directly result in increased subscriptions, thus shortening time-to-profit and enhancing network profitability. While increasing site density to enhance sector carrier throughput and meet edge subscribers’ data rate requirements, Huawei employs new base station features to enhance system performance. These features include MIMO BF, UL FFR, UL 64QAM, UL collaboration spatial multiplexing (CSM), and UL MIMO. Coming with different advantages, these Editor: Xu Ping