Title of Invention: Single Carrier Multi rate transmission

Scheme

[0001 ] [With demand of faster devices, requirement of higher bandwidth transmission has increased rapidly after Fourth Generation - Long Term Evaluation (4G - LTE).

[0002] To fulfill the high requirements of bandwidth, fifth generation (5G) will be utilizing the super high frequencies.

[0003] 5G will provide the faster network for IP telephony, mobile web access, gaming services, HD mobile TV, Video conferencing and 3D TV.

Technical Field

Background Art

[0004] Services for 5G can be provided by utilizing the variable rate transmission schemes.

[0005] The available variable rate transmission schemes are as follows

• Multi code Multi Carrier - Code Division Multi Access (me MC - CDMA)

• Variable spreading length (VSL) MC - CDMA

• Group Orthogonal - Orthogonal Frequency Division Multi Access (GO - OFDMA)

[0006] In me MC - CDMA, higher rate data streams are first multiplexed into a number of sub streams, such that the rate of sub streams data will be same as lowest rate data stream. After multiplexing, each sub stream is allocated with different spreading code, in a manner, higher rate users will utilize multi codes for their transmission.

[0007] However, in VSL MC-CDMA, higher rate data streams are spread with shorter length spreading codes and low rate data streams are spread with longer rate spreading codes. After spreading, rate of lower and higher data streams will be same, the performance of low rate data streams is better with respect to high rate data streams because short length codes are utilized for higher data rate streams.

[0008] GO - OFDMA was proposed by taking concept from GO - MC - CDMA, In GO - MC - CDMA, users are separated into orthogonal groups and each group acts like individual MC-CDMA. Since number of users in a group will be less when compared to total number of users, hence the detection of bits at the receiver will be simpler, in GO - OFDMA, more than one bit of a user is considered, the peak to average power ratio (PAPR) performance of GO - OFDMA is better than the GO - MC - CDMA, VSL MC - CDMA and multi code MC - CDMA. [0009] In 4G, Single carrier (SC) scenario of OFDMA was preferred for the uplink transmission because SC provide the better PAPR compared to OFDMA, SC - FDMA also have better frequency diversity w.r.t. to MC - CDMA and OFDMA, however a limitation of Carrier frequency offset was imposed for good reception.

[0010] GO - OFDMA with Carrier interferometry (Cl) Codes are able to counter the CFO effect and able to provide the good reception even in adverse CFO situation.

Summary of Invention

[001 1 ] The application claims that single carrier (SC) version of multi rate GO - OFDMA scheme can be provided which will provide the better performance w.r.t. other multi rate transmission schemes.

[0012] In SC GO-OFDMA, data streams will be separated on the basis of rates in different groups, these groups are orthogonal to each other and in a group, different users of same rate are considered, the data bits are spread with orthogonal pseudo random codes and after spreading, Fast Fourier transform (FFT) operation is applied on the group output followed by subcarrier mapping and Inverse Fast Fourier transform (IFFT).

[0013] The transmitted signal for SC GO - OFDMA can be summarized as

[0014] With‘A’ the signal amplitude, d\ _q is i ^th data bit of q ^th user of I ^th group, c _{l q} [fc] being the k ^th chip of the spread code for i ^th data bit of the (“user and G _t is the transmitted chip shaping filter’s impulse response.

Advantageous Effects of Invention

[0015] The performance of SC-GO-OFDMA is better with respect to multi rate GO-OFDMA, VSL - MC - CDMA, Multi code MC - CDMA since performance of GO - OFDMA is best with reference to all variable rate scheme

[0016] [Table 1 ] The Below table specify the signal to noise ratio (SNR) Gain achieved by SC - GO - OFDMA w.r.t. GO - OFDMA scheme in harsh Rayleigh channels at BER of 10 ^-4 .

Brief Description of Drawings

Fig.1

[0017] [Fig.1 ] illustrates the block diagram architecture of the multi rate GO - OFDMA scheme. Each Class will have Q _L users of I ^th rate data. Total number of classes is L. Total number of subcarriers are N.

Fig.2

[0018] [Fig.2] illustrates the transmitter block diagram architecture of the multi rate SC - GO - OFDMA scheme. Each Class will have Q _L users of I ^th rate data. Total number of classes is L. Total number of subcarriers are N. After spreading, the N/L point IFFT (Inverse Fast Fourier Transform) is performed before subcarrier mapping and N point Fast Fourier Transform (FFT).

Fig.3

[0019] [Fig.3] shows the performance of SC - GO - OFDMA scheme w.r.t. GO - OFDMA scheme after passing through the harsh Rayleigh channel. Here BPSK modulation was utilized for the both schemes. Simulations are carried out with N = 64 subcarriers and total number of 15 users such that

• Class I - 1 user with rate 1024 kbps

• Class II - 2 users with rate 512 kbps

• Class III - 4 users with rate 256 kbps

• Class IV - 8 users with rate 128 kbps

In Fig, the comparison is shown for one class users and similar kind of advantage is achieved in all class as shown in Table 1 .

Detail Description of Embodiments

[0020] Single carrier scheme gives the better performance thus it is preferred in the 4G uplink transmission. In 5G, the transmission will happen with higher frequency and this will make the channel characteristics harsh for transmission. Here it is shown that by utilizing the architecture of SC - GO - OFDMA better BER gain can be achieved in harsh channel.

[0021 ] SC - GO - OFDMA can be utilized to transmit multi rate data streams simultaneously utilizing single transmitter architecture and giving better performance with respect to others. Industrial Applicability

[0022] This scheme can be utilized in the 5G devices for better reception of transmission. In 5G, the network will be small and number of users will be large to accommodate, thus this scheme will be viable candidate to switch.

[0023] Since BER performance of this scheme is better and PAPR (peak to average power ratio) will be low, because GO - OFDMA PAPR is low. Hence it will be immune to the jammer signal. Hence it will be viable candidate for jamming prone scenario.

Citation List

Patent Literature

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