Experimental Performance Test on Smartphones in HSDPA Communications Systems

Transcription

1 Experimental Performance Test on Smartphones in HSDPA Communications Systems 1 Víctor Caldera-Chacón, 2 Sergio Vidal-Beltrán, 3 Montserrat Jiménez-Licea, 4 Carmen Jiménez-Álvarez Instituto Poltécnico Nacional, Posgrado en Ingeniería de Telecomunicaciones, ESIME-Zacatenco, México DF ABSTRACT This paper describes the characteristics of data transmission in a communication system of third generation cellular transition (3.5G) which is improved in terms 3G data transfer rates of both the DL (Down Link, Downlink) and UL (Up Link, Link Up). The research is focused on the mobile terminal, making a sensitivity analysis on different smart phones "Smartphones" from different manufacturers, through power variations of the cell phone as it is a fundamental parameter to evaluate their performance and make a comparison between different mobile equipments. Keywords: UMTS, HSDPA, 3.5G, WCDMA 1. INTRODUCTION 3G is short for third-generation mobile telephony. The services associated with the third generation provide the ability to transfer both voice data (a telephone call) and non-voice data (such as downloading programs, exchanging , and instant messaging). This evolution side view of GSM GPRS- EDGE passes, also known as 2.5G and characterized to reach speeds up to 384Kbps. The initial evolution to third generation is also known as UMTS (Universal Mobile Telephone System), allows higher speeds up to 2 Mbps [1]. One of the most important characteristics of the 3G network that has been developed to be compatible with the other GSM systems. This interoperability of systems and services ensure the continued experience of using international roaming users have had to GSM. The Roaming 3.5G service is provided according to the availability of this technology in the various operators. 3G networks available worldwide are mainly 850, 900, 1800, 1900, 2100 Mhz. In America they use the 850 and 1900 MHz frequencies. Most 3G mobile phones currently works in 1800 and 2100 MHz for European and Asian standard. 2. HSDPA HSDPA (High Speed Download Packet Access) is an improved air interface WCDMA which provides a higher transmission for the downlink and the ability to develop new services that require high transfer rates. Originally transmitted to the flow to the user were used the transport channels DCH (Dedicated Transport Channel) and DSCH (Downlink Shared Channel). When it was lower speeds could be resorted to the channel FACH (Forward Access Channel). For HSDPA was created the HS-DSCH transport channel (High Speed-DSCH) for the transport of user information. On HS-DSCH will introduce a new called 16QAM modulation which provides a better optimization of the transfer channel, the modulation being multifasorial who has a low S/N (Signal/Noise) relation, which means is susceptible for interference on the radio path. To correct this problem, will implemented error correction techniques as: AMC (Adaptive Modulation and Coding) and HARQ (Hybrid Automatic Repeat Request) [2]. 2.1 AMC AMC is responsible for compensating the instability of the radio channel by adjusting the transmission parameters, such as: coding and data modulation. This setting does base on the CQI (Channel Quality Indication). The modulation and coding methods are called TFRC (Transport Format and Resource Combination). Table 1 shows the types of modulation, code efficiency and maximum transfer rates for different TRFC's. Table 1: Relationship between TRFC's and their speeds using Multi-Codes RELATIONSHIP BETWEEN TRFC S AND DATA RATES Code Maximum TFRC Modulation Efficiency (Mb/s) 1 QPSK ¼ QPSK ½ QPSK ¾ QAM ¼ QAM ¾ 1.7 AMC also selecting suitable TFRC's canal is responsible for setting the transmission power based on measurements made by the physical channel CPICH [3]. 2.2 HARQ The AMC can make decisions based on false information CQI, it may be that the measurement cycle for CQI was not fast enough to detect one fast fading 852

2 signal in this case would be selected modulation and coding appropriateness to channel and perhaps a different transmission power causing errors in the transmission of information, this is where is used HARQ (Hybrid Automatic Repeat Request), Hybrid Automatic Retransmission Request) that allows a network element detects errors and requests retransmission of erroneous packets. 3.1 UMTS test scenario with HSDPA technology The items considered to perform the different tests for mobile terminals include: Mobile terminal. Which considered 2 parts: Compared with the conventional ARQ, the hybrid has the advantage of combining the received transmissions and retransmissions corresponding thus helps reduce the number of retransmissions needed since every packet sent has less possibility of errors, this method is called in-incremental redundancy and is one of the modes of operation of the HARQ. The relay method used to avoid delays is the simplest, it works with a mechanism received acknowledgment confirming that the sent packet has errors or not. The HARQ operation cycle is as follows: It sends the data packet with a CRC (Cyclic Redundancy Check) on the other hand, the receiver applied to data received cyclic redundancy algorithm, the result is compared with the code sent in the transmission and if both codes are all the receiver sends an ACK (Acknowledged), otherwise it sends a NACK (No Acknowledge) requesting retransmission [4]. 3. DATA TESTING UMTS WITH HSDPA TECHNOLOGY Below, we describe in detail the methodology used to test HSDPA data, note that the core under study in this paper is the mobile terminal, thus making these tests, measurements were made with 3 different smartphones, those which are most in demand at present, in order to make evident the performance of each of them, the Table 2 lists the equipment with which they were tested. Table 2: Mobile equipments Mobile Equipments Samsung Galaxy Young Samsung Galaxy S2 Samsung Galaxy S3 For these tests, the analyzer uses the MT8820C Radio analyzer, which is an instrument that allows testing of transmission and reception in mobile communications systems and call evidence. It is noteworthy that the team works between the frequency ranges of 30 MHz to 2.7GHz, which allow working with different cellular communication technologies including frequency bands I to XIX UMTS therefore, equipment allows measurements in different technologies such as WCDMA / HSDPA GSM / GPRS / EGPRS, cdma2000 1x (IS-2000), cdma xEV-DO, PDC and PHS / ADVANCED [5]. The different model of Smartphones. A USIM/MICRO-USIM test, which allows registration of the mobile terminal to the radio analyzer. Radio communications Analyzer. Which considered 3 parts: The MT8820C Equipment, where they were tested data. A shielded box to avoid interference that can be generated of the outside due to radio bases are located near the area where they were tested. A coaxial cable, which allows connection between the shielded box and the communications analyzer. Figure 1 shows the scenario for testing data with mobile devices. Fig 1: Test Scenario UMTS data with HSDPA. 3.2 Measurement Procedure in UMTS with HSDPA. Proceed as follows. 1. Turns on radio analyzer. 2. Figure 2 shows the main screen display of "parameters" in which adjustments will be made as indicated. 853

3 13. Button Screen is pressed and go to Fundamental. 14. With direction buttons the screen is lowered to where measurement appears "HSDPA throughput" Fig 2: WCDMA "Parameter" Display for HSDPA Test. 3. Button std is pressed and verify that it changes to WCDMA. 4. In "Channel coding" select "Data". 5. In Test Loop Mode select On. 6. In Band Indicator select Band V. 7. Adjust the "Output Level" from the base station to -40dBm, to ensure communication between the station and the mobile terminal. 8. Enter the part of "H-Set" of the equipment and select the measurement to be carried out according to the modulation (1, 2, 3, 6 or 8). 9. USIM/MICRO-USIM is inserted on the mobile terminal. 10. Turns on the mobile terminal. 11. Is deposited inside the shielded box. 12. Is displayed on the screen of the analyzer that the equipment it has registered (displayed as Idle Regist ). 15. Button Single is pressed and save the screen and the data obtained. 4. RESULTS The test set supports the following H-Set given in 3GPP TS sc.8 defined in Table 3. Table 3: Rates and Modulation in the HS- PDSCH Channel. TYPE OF MODULATION AND TRANSFER RATE FOR EACH H-SET IN HS-PDSCH H- TRANSFER RATE MODULATION SET (Kbps) 1 QPSK MAQ QPSK QAM QPSK QAM QPSK QAM QAM In Smartphones Samsung Galaxy S2, S3 and Young, were tested for these different types of H-set, which will be described in the following. The first case corresponds to the equipment Samsung Galaxy Young, where H-set were tested from 1 to 6 for QPSK and 16 QAM. Table 4 shows the cases where under certain power levels gave the best data transfer rate between the mobile and radio equipment. 854

4 Table 4: Obtained Data HSDPA Tests With the Equipment Samsung Galaxy Young. SAMSUNG GALAXY YOUNG EQUIPMENT 1 KSPQ -62, MAQ KSPQ -62, MAQ KSPQ 69, 71,-73, MAQ 69, KSPQ 69, MAQ -62, -65, As can be seen in some cases, for different power levels, maintaining maximum data transmission rate according to the modulation and H-set as in the best of cases have a maximum rate of 4689 Kbps for this equipment. The second case corresponds to the Samsung Galaxy S2 equipment, various tests were performed, from H-set 1 to 8 with QPSK, 16 QAM and 64 QAM, where values were obtained different data transfer rate, depending on the variation the power received by the Smartphone. The values obtained from the tests with this equipment are shown in Table 5. Table 5: Obtained Data HSDPA Tests With the Equipment Samsung Galaxy S2 SAMSUNG GALAXY S2 EQUIPMENT 1 KSPQ 1 16 MAQ 2 KSPQ 2 16 MAQ 3 KSPQ -62, -65, -68, - 69, , -65, -67, - 68, -69, -70, - 71, -71.2, -73, -75, , -69, -71, - 72, -73, -74, - 75, -75.1, , -75.3, - 78, -81, , -69, -70, , -65, -68, - 71, -72, -73, MAQ 6 KSPQ 6 16 MAQ 8 64 QAM 74 68, -71, , -65, -66, - 67, , -63, -64, - 65, -67, -70, , -56, -57, - 58, -59, -62, In the case of this equipment can be seen that the difference Galaxy Young, remains more stable data transmission over power variations, which gives a greater tolerance to maintain a fixed rate transmission, when the actual event a person is with mobile in motion with respect to a node B with what remains in the-dents, with Kbps maximum transfer rate that supports the equipment. The third case is the Galaxy S3 equipment to which various tests were performed from H-set 1 to 8 with QPSK, 16 QAM and 64 QAM, where values were obtained as shown in Table 6, it also note that these values are where accomplished to some variation of power received by the computer, to obtain the fastest rate of data transmission. Table 6: Obtained Data HSDPA Tests With the Equipment Samsung Galaxy S3. SAMSUNG GALAXY S3 EQUIPMENT 1 KSPQ MAQ KSPQ -62, -65, MAQ KSPQ 62, MAQ -62, KSPQ MAQ QAM According to the values obtained have to this team, showed less sensitivity to maintain a fixed rate of transmission of data, which is difficult when there are variations in power, keep the maximum transmission rate according to the H-set and modulation used, with Kbps maximum supported rate. Of the three equipments, can be noted that the best performance in sensitivity and tolerance for data transmission in the first place is the Samsung Galaxy S2, Samsung Galaxy Young subsequently and finally the Samsung Galaxy S3. 855

5 5. CONCLUSIONS Based on the results obtained have benefits considering 4 different groups: Academic. Was possible to analyze the mobile terminals know the performance parameters for different equipment manufacturers, resulting pattern for future investigations are conducted with newer computers, as well as different technologies as 3G and 4G. Manufacturer. This research shows that the manufacturers of mobile devices, the current status of performance of their products so that they make design improvements to the existing current and future market devices. Mobile Communications Operators. Lets consider the performance of the equipment for the design of service coverage. Consumer. Lets make a better choice when wanting to purchase one of the equipment with which are experienced so that is satisfied with its product. REFERENCES [1] Wireless Communications, David Roldan, Alfa omega Ra-Ma. [2] UMTS Architecture, Mobility and Services, Heikki Kaaranen, Ari Ahtianen, Siamak Naghnian, John Wiley & Sons. [3] UMTS: The Fundamentals, Walke, Bernhard H., John Wiley & Sons. [4] Mobile Communication Systems, Parsons, J.D., Halsted Press. [5] W-CDMA and GSM testing with the MT8820A Radio Communication Analyzer, mt8820c_ef1500.pdf 856