HSPDA [High Speed Downlink Packet Access] was released in 3GPP [Third Generation Partnership Project] Release 5 for indoor and urban outdoor high speed data access at 10 MBPS [Mega Bits Per Second] range (14.4 MBPS theoretical).
HSDPA [High Speed Downlink Packet Access] is based on the following key concepts:
- Adaptive modulation
- 16QAM [Quadrature Amplitude Modulation] and coding schemes
- QPSK [Quadrature Phase Shift Keying] with data rates up to 14.4 Mega BPS per channel and eventually up to 50+ MBPS
- HARQ [Hybrid Automatic Repeat reQuest] – retransmission protocol
Fast packet scheduling by the MAChs [Medium Access Control high speed] with many different priority queues and user priority levels by using MIMO-Multiple Input Multiple Output as well as other antenna systems and asymmetric allocation of frequency spectrum in multi-carrier cells higher data speeds are forecasted.
MIMO [Multiple Input Multiple Output] Multiple Antennas – Multiple Frequency antennas increase coverage, increase data rates, and reduce co-channel interference. Spatial Multilink Beamforming based on 2×3+ – 2 Frequencies – Multiple Antennas further adds performance and directional unicasting. In the animation is a brief comparison of wireless service data speeds. One path is GPRS [General Packet Radio Service] becomes EDGE [Enhanced Data Global system for mobile Evolution] (an always-on IP [Internet Protocol] network) and eventually becomes WCDMA [Wideband CDMA] or UMTS [Universal Mobile Telecommunications Service] (supports GSM, GPRS, EDGE, WCDMA, and HSDPA).
Along the other path, CDMA becomes 1XRTT – 1X-EV-DO – 1X-EV-DV. Used with UMTS, HSPDA [High Speed Downlink Packet Access] offers the highest data-throughput rates of any cellular-data technology specified with peak rates of 10-50+ Mega BPS. HSDPA also uses a wide variety of RF [Radio Frequency] techniques to provide this service. Here are a few of the many potential concepts being explored. Spatial Diversity is provided by transmitting identical information via channels via uncorrelated fading (separating the channels via 10-20 radio frequency wavelengths or in polarization orientation – horizontal or vertical). SDMA [Space Division Multiple Access] or SDM [Space Division Multiplexing] can be used to increase the downlink cell throughput by scheduling packets to users served by different beams. This limits mutual interference between these users, making it possible to reuse the same channelization code resources. Beamforming is used to increase throughput by user-specific beamforming and beamforming with a grid of fixed beams (using a dedicated scrambling code which can be assigned to each beam making a channelization code tree in each beam).
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