tailieunhanh - Enabling Technologies for Wireless E-Business phần 2

CDMA2000 CDMA2000 là một sự tiến hóa từ IS-95 và có thể hỗ trợ tốc độ dữ liệu cao hơn các giao diện không khí. CDMA2000 hiện đang được các tiêu chuẩn của Dự án Quan hệ đối tác thứ ba thế hệ 2 (3GPP2) và là một gia đình tiêu chuẩn. | 32 D. Shen and . Li cdma2000 cdma2000 is an evolution from IS-95 and is able to support high rate data over the air interface. cdma2000 is currently under the standardization of Third Generation Partnership Project 2 3GPP2 and is a family of standards. cdma2000 1x has been widely deployed over the world. Over the bandwidth of MHz cdma2000 1x 1x means single carrier can support a peak rate of kbps. cdma2000 1xEV-DO 1x evolution data optimized can reach a peak rate of Mbps. The cdma2000 1xEV-DV 1x evolution for integrated data and voice is further expected to deliver a maximal rate of Mbps. In this part we provide a brief introduction on cdma2000 1x cdma2000 1xEV-DO and cdma2000 1xEV-DV. cdma2000 1x cdma2000 1x operates in various frequency bands of 450 800 900 1 700 1 800 1 900 and 2 100 MHz and is fully backward compatible with IS-95. When compared with IS-95 cdma2000 1x has higher voice capacity supporting 35 voice calls per sector per carrier. In contrast the voice capacity for IS-95 is 22 voice channels per sector per carrier. This increase in voice capacity is due to a number of factors. Over the forward link fast power control is employed a 1 4 code rate is introduced and transmit diversity can be implemented. Over the reverse link the capacity improvement mainly comes from the newly adopted coherent demodulation. For voice and data there are three commonly used channels. The fundamental channel FCH is to carry voice data and signaling at rates from 1 200 bps to kbps. The high data rates are supported by the supplemental channel SCH whose peak rate can be 16 or 32 times of FCH. The dedicated control channel is used for signaling or bursty data access. For data traffic cdma2000 1x can support a peak data rate of kbps release 0 and can be further increased to kbps release A . The theoretical maximal rate for cdma2000 1x is 628 kbps which is achieved by combining two SCHs at kbps plus an FCH at a rate of