3G

Long Mp3 3G technology services is the latest in mobile communication services. 3G here is a term that denotes "third generation". The 3G service is the third innovation, the analog cellular technology generation is the first generation innovation, digital mobile is the second generation,

The 3G mobile service is the best technology for the true multimedia cell phone that are typically known as smart phones. These phones feature an increased bandwidth and wonderful transfer rates. The phone is also able to play various web-based applications and the various audio and video files designed to be played on a phone.

The 3G services comprise of several cellular access technologies. The three most common cellular technologies are the CDMA2000, which is based on 2G Code Division Multiple Access, the WCDMA or the Wideband Code Division Multiple Access and the TD-SCDMA – the Time-division Synchronous Code-division Multiple Access

The 3G service networks have an amazing data transfer speed. In fact it can transfer data for up to 3 Mbps that means that it would take almost 15 seconds to download a 3-minute long MP3 song. In comparison, the fastest 2G phones can only achieve up to 144Kbps which means that using them it would take about 8 minutes to download a 3-minute song.

Why 3G is better than 2g?

1. Use of higher order modulation:   16QAM is used in the downlink instead of QPSK to enable data to be transmitted at a higher rate. This provides for maximum data rates of 14 Mbps in the downlink. QPSK is still used in the uplink where data rates of up to 5.8 Mbps are achieved. The data rates quoted are for raw data rates and do not include reductions in actual payload data resulting from the protocol overheads.
2. Shorter Transmission Time Interval (TTI):   The use of a shorter TTI within 3G HSPA reduces the round trip time and enables improvements in adapting to fast channel variations and provides for reductions in latency.
3. Use of shared channel transmission:   Sharing the resources enables greater levels of efficiency to be achieved and integrates with IP and packet data concepts.
4. Use of link adaptation:   By adapting the link it is possible to maximize the channel usage.
5. Fast Node B scheduling:   The use of fast scheduling within 3G HSPA with adaptive coding and modulation (only downlink) enables the system to respond to the varying radio channel and interference conditions and to accommodate data traffic which tends to be "bursty" in nature.
6. Node B based Hybrid ARQ:   This enables 3G HSPA to provide reduced retransmission round trip times and it adds robustness to the system by allowing soft combining of retransmissions.

 The first country to start 3G service on a great scale was Japan where by 2005 nearly 40% of consumers used 3G network only. With 2G technology becoming outdated in Japan,almost all the 2G networks have now been shifted to 3G networks.

3G gives the ability to transfer both voice as well as non-voice based Data at a much faster level. While marketing 3G services, video telephony is famously referred as a killer application. 3G networks have not been upgraded from 2G networks and do not function on the same frequency spectrum. For 3G services new networks need to be fitted and new frequencies are allocated to the mobile operators.

3G HSPA of High Speed packet Access is the combination of two technologies, one of the downlink and the other for the uplink that can be built onto the existing 3G UMTS or W-CDMA technology to provide increased data transfer speeds.

The original 3G UMTS / W-CDMA standard provided a maximum download speed of 384 kbps. With many users requiring much high data transfer speeds to compete with fixed line broadband services and also to support services that require higher data rates, the need for an increase in the speeds obtainable became necessary. This resulted in the development of the technologies for 3G HSPA.

3G UMTS HSPA constituents

There are two main components to 3G UMTS HSPA, each addressing one of the links between the base station and the user equipment, i.e. one for the uplink, and one for the downlink

Uplink and downlink transmission directions

 The two technologies were released at different times through 3GPP. They also have different properties resulting from the different modes of operation that are required. In view of these facts they were often treated as almost separate entities. Now they are generally rolled out together. The two technologies are summarised below:

• HSDPA - High Speed Downlink Packet Access:   HSDPA provides packet data support, reduced delays, and a peak raw data rate (i.e. over the air) of 14 Mbps. It also provides around three times the capacity of the 3G UMTS technology defined in Release 99 of the 3GPP UMTS standard.
• HSUPA - High Speed Uplink Packet Access:   HSUPA provides improved uplink packet support, reduced delays and a peak raw data rate of 5.74 Mbps. This results in a capacity increase of around twice that provided by the Release 99 services.

Beyond 3G HSPA

·         With the elements of 3G HSPA launched, further evolutions were in the pipeline. The first of these was known as HSPA+ or Evolved HSPA. The evolved HSPA or HSPA+ provides data rates up to 42 Mbps in the downlink and 11 Mbps in the uplink (per 5MHz carrier) which it achieves by using high order modulation and MIMO (multiple input, multiple output) technologies.

·         In addition to 3G HSPA, and its evolutions, the next evolution for 3G UMTS is known as LTE - Long Term Evolution. This uses a completely different air interface that is based around OFDM as the modulation format. While many operators have opted to migrate directly from UMTS to LTE, the majority are using 3G HSPA to upgrade their existing 3G networks.