Difference Between Fdd And Tdd Pdf

difference between fdd and tdd pdf

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The APT band plan has been designed to enable the most efficient use of available spectrum.

Microwave links typically use Frequency-division duplexing FDD which is a method for establishing a f ull-duplex communications link that uses two different radio frequencies for transmitter and receiver operation.

For most normal LTE deployments the frequency division duplex, FDD is used, and paired spectrum with equal bandwidth in up and downlinks is utilised. It is essential that any cellular communications system must be able to transmit in both directions simultaneously. This enables conversations to be made, with either end being able to talk and listen as required. Additionally when exchanging data it is necessary to be able to undertake virtually simultaneous or completely simultaneous communications in both directions. It is necessary to be able to specify the different direction of transmission so that it is possible to easily identify in which direction the transmission is being made.

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The APT band plan has been designed to enable the most efficient use of available spectrum. Therefore, this plan divides the band into contiguous blocks of frequencies that are as large as possible taking account of the need to avoid interference with services in other frequency bands. The guardbands serve the purpose of mitigating interference with adjacent bands while the FDD center gap is required to avoid interference between uplink and downlink transmissions.

The two arrangements are shown graphically in figures 1 and 2. Table 1. Currently, the FDD configuration is the one which has been studied most widely and is much more popular across the world.

By the end of the year, there are twice as many mobile broadband as fixed broadband subscriptions [38]. July - approximately Equipped with a frontal HD camera, iPhone again sets expectations for increasingly higher mobile data consumption. The APT band plan has been developed over a 2. For the overall success of the creation of the harmonized band plan, high degree of cooperation among industry stakeholders governments, vendors, operators, associations, and other was key.

As a result, the APT band plan is very well-thought from the technical point of view and is able to meet modern and future requirements by networks, user equipment and growing demand of connectivity. Because many countries across the globe have adopted the APT band plan, substantial economies of scale are bound to be created. That will lead to personal devices' and network elements' price erosion and thus, also to increasingly higher penetration of mobile devices and mobile internet.

The APT band plan has already become a multi-regionally harmonized spectrum band that will provide a coherent ecosystem for LTE devices. Most Asian countries have already opted for the APT band; there is a strong evidence of a rising regional consensus among the vast majority of Latin American countries.

Europe's "second" digital dividend matches the second duplexer of the APT band plan which implies that the user equipment, as well as network elements will be compatible with those of the APT band plan. With the inclusion of two-duplexer system in the devices and network equipment, full interoperability is guaranteed across the entire band of the APT band plan.

On the contrary, in the US band plan, there are two or three different device ecosystems which translate to non-interoperability within the country, and severe limitations most probably, practically unavailability of international roaming.

This enables operators to enjoy much wider channels comparing to the blocks available within the US band plan. That translates to much greater efficiency of networks, higher data throughput levels, lower latency and less investments needed for network deployment, all other factors being equal.

Wider channel sizes are crucially important for the networks of the nearest future because of the growth of mobile data and projected capacity demand. The APT band plan assures appropriate protective measures for other services in adjacent bands which allow avoiding harmful interference from TV services in lower bands as well as from cellular networks in upper bands. In the near future, the phenomenon of asymmetric traffic when downlink experiences more traffic than uplink can be mitigated by applying signal processing techniques that are currently under consideration in the standards development process for the APT band plan.

US band plan was developed significantly earlier than the APT band plan. Due to this fact, the ecosystem of this band plan is relatively well-developed with two large networks already operating commercially and with a number of user devices existing on the market.

Another existing challenge is the advancement of its own ecosystem, which in turn depends on equipment vendors: terminal devices manufacturers HTC , Apple , Samsung , Nokia , etc. The development of the ecosystem depends heavily on the demand that exists on the market and is a function of the created economies of scale.

Most likely, China will follow the TDD configuration of the APT band plan, thus most probably becoming one of a handful of markets in the world that support such configuration, but still an important and large one. It should be said, however, that in a number cases the TDD configuration proves to have certain advantages, such as larger capacity to bear with downlink disproportionately exceeding the uplink data transmission.

Therefore, it will not add up to economies of scale of neither of the two and a completely separate ecosystem might likely be developed.

In the APT FDD configuration, two overlapping duplexers are required to cover the entire band due to the limitations by current filter technologies.

The existence of two duplexers in the APT band plan and the fact that European, Japanese and perhaps some other future networks will only work with one duplexer set, raise a question of whether user and network equipment manufacturers will incorporate both duplexers in their equipment or will create two parallel configurations — one with only one duplexer and another one with both of them.

Although the dynamics of the market such as the ever-increasing complexity of chipsets , multi-band support by chip manufacturers demonstrate that the most likely outcome is the inclusion of both duplexers in all devices. As of , most equipment vendors have released two versions of their radio units: one dedicated to the lower band and another one dedicated to the upper band.

Frequency arrangements of the US band plan and the APT band plan substantially overlap thus making them largely incompatible. More specifically, duplex spacing and guardband peculiarities of the APT band plan is what differentiates it most. US band plan, in its turn, is characterized by a number of inconsistencies: i non-existence of in-band interoperability i.

Japan, one of largest and most advanced Asian markets and the global technology leader is using the upper duplexer part of the APT band plan and thus will enjoy being the part of the ecosystem of the APT band plan too. This extent of harmonization will lead to economies of scale which will in turn drag down the prices of terminals, speed up adoption of smart devices and finally convert to socio-economic benefits. At the given moment, the user equipment UE for this segmentation scheme has not yet been released commercially.

In the same time, the development of 3GPP and ITU standards bands 28 and 44 and evident signals that has been sent to the market by many countries in Asia, Latin America and elsewhere, indicate that technological developments of the required ecosystem first of all, in terms of user equipment and network equipment are currently underway. Some of the strongest signals for the future demand have been sent by large markets, such as Japan, India, Indonesia, and above all, Mexico.

Another point that is worth to mention is that the standardization work that has been carried out by the 3GPP was strongly supported by many key companies from the industry.

That also proves that the equipment manufacturers are in the process of the commercialization of UE and network elements driven by the creation of significant market by the APT band plan. All that seems to indicate that first prototypes of APT devices will appear in the Q2 of and market releases are to be expected in the second half of In Latin America, for example, the National Spectrum Agency ANE of Colombia has announced that Huawei, ZTE and Ericsson will conduct tests in the band under the standard APT pipeline in the first quarter of , using equipment developed by the leading manufacturers with the goal to auction off the spectrum in August In countries such as Indonesia, Singapore, Thailand, Vietnam, Uruguay, Paraguay, Peru and a few others it is scheduled to be adopted in the nearest future.

That decision also takes into account the need for European countries to better study issues regarding the channel plan and to carry out compatibility studies regarding other services in the Region and on other topics, before taking final position on the best suitable allocation and associated regulation. Generally speaking, it is very important that the spectrum is used in the same way across as many markets as possible to create economies of scale.

That, in turn, leads to lower prices for the equipment thus increasing the adoption of the technology and having a direct and indirect impact on the economic growth. This growth consists of enhancement of productivity, job creation, entrepreneurship, infrastructure investment, taxation; all leading to GDP growth.

Creation of economies of scale is vital for mass production of equipment and its further adoption in target markets. Overall, the greater economies of scale are, the lesser end user prices will be established and the vaster will be the adoption of the technology that translates to socio-economic benefits.

Speaking about the ecosystem availability timeframes, many stakeholders expect the APT band plan ecosystem to develop rapidly as countries identify and auction spectrum with this frequency arrangement.

However, at least in the short- and medium-term, there will be separate markets for UE in these two existing band plan configurations. That, by itself, represents a significant market of an order of million people.

However, the recent developments around the propagation of the APT band plan across Asia-Pacific region, Latin America, and thanks to the compatibility of the European frequency arrangements, as well as the situation in Africa and Middle East, project confidence that a far bigger market is being created worldwide. Summed up, the prospective overall market for the APT band plan translates to a figure of at the very least 3 billion people across the globe. With ongoing studies of the digital dividend in the world, that number is might increase and include nearly all the rest of the world.

The number of such countries of the region is bound to rise. These countries alone represent a market equal to the one of the US band plan — around million people. The logical outcome of the ongoing regional harmonization process in Americas will be the resulting market of an order of million consumers. Given the size of the potential market that is on the verge of being created, the socio-economic benefits caused by booming access and adoption of the mobile internet by all social layers of population and driven by rocketing penetration of smart devices will be overwhelming and transformational.

Table 4. Table 5. They correspond to the frequency arrangement of the Rec. ITU-R M. The most favored, popular mobile broadband technology internationally for the digital dividend spectrum appears to be the FDD-LTE technology. LTE is known to offer operators and end users high data throughput and low latency which are the two main characteristics of a technology that is aimed to be used for data transmission.

While actual speeds experienced by users will be dependent on equipment and the number of users connected to any cell, it is clear that LTE offers speeds which could result in a step-change in mobile broadband connectivity. The move to LTE is seen as the key next step for mobile network operators aiming to respond to the increasing demand for mobile data access.

LTE offers greater spectral efficiency, allowing the provision of higher data speeds and greater data allowance, at lower cost. This will be particularly important for MNOs as average revenue per user from voice and text services falls. It will be able to provide both mobile and fixed wireless broadband services. This move is led mainly by equipment manufacturers and mobile network operators in China.

At the current moment in time, though, the technology is largely untested. Higher frequency bands required even more base stations.

The duplexer is a filter that provides isolation of the transmitter leakage to its own receiver. In a mobile connected device, the transmitter and receiver are linked to the same antenna by means of a duplexer. If the duplexer isolation is not sufficient then the handset may experience self- desensitization. Multi-mode, multi-band handsets often have mode- and band-specific duplexers. Duplexer technology affects choice of duplex separation and centre band gap which have been designed for the APT band plan with these considerations in mind.

Duplex spacing is the separation between the uplink channel and the corresponding downlink channel. A larger separation implies less likelihood of self-interference between a handset transmitter and its own receiver. Because a power amplifier out of band response is related to the bandwidth, the duplex separation requirement is also dependent on the carrier bandwidth in order to protect the receiver from self-interference.

Centre gap is a key characteristic of FDD-based frequency arrangement represented by the gap between frequency blocks assigned for downlink and uplink respectively in the FDD-based arrangement as illustrated in Figure 5. It is common understanding that the duplex spacing and centre gap influence the duplexer performance so that larger separation brings the better isolation performance between downlink and uplink. Technically, this size of spacing affects the duplexer performance in the following two technical aspects:.

To prevent self-desensitization, a duplexer must attenuate Tx emissions at the own Rx frequency band below the Rx noise floor.

The center gap will also determine whether competitive networks can share base station sites with minimum interference and protective site filtering complexity. With the use of a dual duplexer arrangement the individual duplex spacing will be increased, providing at the same time more usable spectrum for FDD.

Dual duplexers are being specified today and would add to the number of band specific duplexers to be accommodated in handsets where physical space is at a premium. Radio waves , due to its nature and physics, can cause harmful interference to networks and equipment operating in a different band plan, i. That is why coherent policies and technical frameworks are routinely developed by countries to mitigate such interference.

From Wikipedia, the free encyclopedia. Telecom band plan for LTE development. This section contains content that is written like an advertisement. Please help improve it by removing promotional content and inappropriate external links , and by adding encyclopedic content written from a neutral point of view.

LTE FDD, TDD, TD-LTE Duplex Schemes

A linear bus topology is the simplest type of network topology. Type CD drive: to display the current directory in the. Example: boron. As it turns out, the admittance matrix is easy to formulate. Interference is less as one wired network will not affect the other.

Lte Sniffer. An international team of researchers has discovered a attack methods. But I never find a completely passive sniffing tool. It is equipped w…. You are not allowed to use, supply or own a GPS jammer.

Skip to Main Content. A not-for-profit organization, IEEE is the world's largest technical professional organization dedicated to advancing technology for the benefit of humanity. Use of this web site signifies your agreement to the terms and conditions. We compare the uplink performance of the LTE FDD and TDD modes for a typical Smart Grid scenario involving a large number of devices sending small to medium size packets to understand the advantages and disadvantages of these two modes. An OPNET simulation model is employed to facilitate realistic comparisons based upon latency and channel utilization. We demonstrate that there is a critical packet size above which there is a step increase in uplink latency due to the nature of the LTE uplink resource scheduling process. It is shown that FDD leads to better uplink performance in terms of latency, while TDD can provide greater flexibility when the split between uplink and downlink data is asymmetrical as it is expected to be in a Smart Grid environment.

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Ofdm Python Original papers, fast turnaround and reasonable prices! Call us at Accordingly, OFDM, Orthogonal Frequency Division Multiplexing is used for many of the latest wide bandwidth and high data rate wireless systems including Wi-Fi, cellular telecommunications and.

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Asia-Pacific Telecommunity band plan in the 700 MHz band

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Study on Frequency Synchronization in 3GPP LTE System for FDD and TDD Modes

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Algernon T.


Mobile devices in a Time Division Duplexing (TDD) system transmit periodically (​e.g., 1/2 or 1/3 of the time compared to FDD); hence, required rates cannot be.

Amir A.


Traditionally, cyclic prefix CP based method is widely used for fine FOE which is however sensitive to the time synchronization error and multi-path fading channel environment.

Chandler H.


FDD uses lots of frequency spectrum, though, generally at least twice the spectrum needed by TDD. In addition, there must be adequate spectrum separation.

Xalome T.


characterises FDD systems. TDD-based radios of this type can provide performance equal to that of FDD radios, and in the case of bursty IP type traffic, provide.