CN101272573A - Double SIM card mobile phone - Google Patents

Abstract

The invention relates to a mobile communication technique, in particular to a cell phone with two cards. The invention solves the problems of high cost and poor sensitivity of the cell phone with two cards and discloses the cell phone with two cards. The cell phone with two cards of the invention comprises two sets of radio frequency front ends, a set of baseband processor, two SIM card interfaces and a shifting switch. The cell phone with two cards of the invention applies the shifting switch to shift the connection between the two SIM card interfaces and the baseband processor, thus realizing simultaneous standby state of the cell phone with two cards. The cell phone with two cards is mainly used in the cell phone of the GSM network, and can reduce the cost of the cell phone with two cards and greatly save the network establish cost.

Description

Double-card mobile phone

Technical field

The present invention relates to mobile communication technology, particularly a kind of double-card mobile phone.

Background technology

High speed development along with mobile communication technology, GSM (Global System for MobileCommunications as the 2G communication standard, hereinafter to be referred as GSM) technology is through for many years continuous development, formed the network of comprehensive covering, add the speech quality height, support the high-speed mobile communication, become perfect at present communication commercial standard (CS).

The GSM standard, though very perfect, because charge disunity between the domestic operator and factor such as wandering fee is higher have also stimulated the demand of user to double-card mobile phone.The double-card mobile phone of prior art, structure generally comprise as shown in Figure 1: first cell phone system that first radio-frequency front-end, first baseband processor and the first SIM card interface constitute; Second cell phone system that second radio-frequency front-end, second baseband processor and the second SIM card interface constitute.Compare as can be seen with common single deck tape-recorder mobile phone, basically except other functional units such as keyboard and power-supply system be shared, the double-card mobile phone of prior art is exactly the simple combination of two common single deck tape-recorder mobile phones basically.The shortcoming of this double-card mobile phone is, owing to need the complete substantially cell phone system of two covers, at first bring the increase of mobile phone cost, next is that mobile phone belongs to portable communication device, its volume is very limited, be in the cover of two in this confined space cell phone system, realize the standby (work) simultaneously of two cards, influence each other is difficult to isolate fully, the particularly phase mutual interference of radio-frequency front-end, the direct result that produces is exactly the rollback of mobile phone receiving sensitivity, causes double-card mobile phone not reach the sensitivity requirement of 3GPP (3rd Generation Partnership Project third generation partner program) standard code, for mobile phone operators, just need to build more base station, to obtain the good signal coverage rate, will on base station construction, drop into a large amount of funds, the increase that brings network construction cost.

Summary of the invention

Technical problem to be solved by this invention is exactly at prior art cost height, and the low problem of sensitivity that two cover systems influence each other and produce provides a kind of based on the double-card mobile phone of standby mode in turn on the microcosmic.

The present invention solve the technical problem, and the technical scheme of employing is that double-card mobile phone comprises first radio-frequency front-end, second radio-frequency front-end, baseband processor, the first SIM card interface and the second SIM card interface; The first mobile phone systemic-function is finished in described first radio-frequency front-end and the described first SIM card interface and the combination of described baseband processor, and the second mobile phone systemic-function is finished in described second radio-frequency front-end and the described second SIM card interface and the combination of described baseband processor; It is characterized in that, also comprise diverter switch; The described first SIM card interface is connected with described baseband processor by described diverter switch with the described second SIM card interface, and described diverter switch is used to switch being connected of the described first SIM card interface and the described second SIM card interface and described baseband processor;

Further, described baseband processor is controlled described diverter switch according to the communications time slot and is switched being connected of the described first SIM card interface and the described second SIM card interface and described baseband processor;

Further, described first radio-frequency front-end and described second radio-frequency front-end work in the communication network of same pattern;

Concrete, described communication network is the gsm communication network.

The invention has the beneficial effects as follows that the shared cover baseband processor of two cover systems has been saved one and has been enclosed within the baseband processor cost that accounts for larger specific gravity in the mobile phone complete machine cost, has reduced the double-card mobile phone cost.Because the phase mutual interference between two cover systems has been avoided in the special design of circuit structure basically, makes double-card mobile phone sensitivity rollback problem obtain basic solution, can save a large amount of network construction cost.

Description of drawings

Fig. 1 is the double-card mobile phone basic structure schematic diagram of prior art;

Fig. 2 is that communications time slot and SIM card access concern schematic diagram;

Fig. 3 is a double-card mobile phone basic structure schematic diagram of the present invention;

Fig. 4 is the Switch structure schematic diagram.

Below in conjunction with drawings and Examples, describe technical scheme of the present invention in detail.

Embodiment

For the ease of understanding technical scheme of the present invention, below several important parameters are analyzed.

The base station signal covering analyzing:

Consider that link budget improves (unit: dB) to sub-district maximum coverage range (unit: km ²) influence.Suppose in link budget, can obtain the improvement of Δ L (dB), utilize the Okumura-Hata model (to see Laiho for details, J., Wacker, A.and Novosad, T., Radio Network Planning and Optimization for UMTS, John Wiley ﹠amp; What Sons, 2001), can calculate link budget improves the influence of Δ L (dB) to the Δ R/R of sub-district relative radius.Wherein, R is default sub-district effective radius, and Δ R is the relative recruitment of sub-district effective radius.Now getting path loss index is 3.52, then has

$\mathrm{\ΔL}=3.52\×10\lg (1+\frac{\mathrm{\ΔR}}{R})$

The relative recruitment of sub-district area coverage

$\frac{\mathrm{\ΔA}}{A}={(1+\frac{\mathrm{\ΔR}}{R})}^2={\left({10}^{\frac{\mathrm{\ΔL}}{35.2}}\right)}^2$

Table one has provided the link budget improvement, to the demand of the website density of corresponding base station.

Improvement/the dB of link budget	Relative number of base stations
		0.0 expression reference case	100％
1.0	88％
		2.0	77％
3.0	68％
		4.0	59％
5.0	52％
		6.0	46％
10.0	27％

As can be seen from Table 1, when link performance improves about 5.3dB, base station density can reduce about 50%.This shows, improve the mobile phone sensitivity behaviour, for example improve 6dB, can reduce the mobile phone operators input cost of half approximately.The double-card mobile phone of selling does not on the market nearly all solve the standby simultaneously of two cover systems at present, the serious problem that descends of the mobile phone sensitivity that is brought.And the present invention has then solved the requirement of mobile phone operators to double-card mobile phone sensitivity in real time, satisfies the 3GPP standard.

IP3 (3 for two G system ^RdOrder Intercept Point), P _IMDS(Minimum DetectableSignal), _DRThe limiting value of (Dynamic Range) is calculated:

At first, must analyze IP3, according to

$v_o=k_1{v}_i+k_3{v}_i^3+k_5{v}_i^5+k_7{v}_i^7$

If input signal is a simple signal,

v _i＝v _icoswt

Then:

$v_o=k_1{v}_i\cos \mathrm{wt}+k_3{v}_i^3{\cos }^3\mathrm{wt}+k_5{v}_i^5{\cos }^5\mathrm{wt}+k_7{v}_i^7{\cos }^7\mathrm{wt}$

$=(k_1{v}_i+\frac{3}{4}{k}_3{v}_i^3+\frac{5}{8}{k}_5{v}_i^5+\frac{35}{64}{k}_7{v}_i^7)\cos \mathrm{wt}+...$

1) power output can be expressed as in linear zone:

P ₀(dBm)＝P _i(dBm)+G ₀(dB)

Wherein, G ₀Be defined as linear gain:

$G_0=20\lg \frac{k_i{v}_i}{v_i}=20\lg k_i=30.63\left(\mathrm{dB}\right)$

Then the 1dB compression point may be defined as and makes power output depart from the pairing input power value of its linear characteristic decline 1dB, can get:

P ₀₁(dBm)＝P _i(dBm)+G ₀(dB)-1

The place has in the 1dB compression point:

$0.109k_1+0.75k_3{v}_i^2+0.625k_5{v}_i^4+0.547k_7{v}_i^6=0$

Can solve:

$v_i^2=6.1504\×{10}^{-4}$

If port input impedance equates with output impedance, then

$P_i=10\lg (\frac{1}{2}\×\frac{v_i^2}{R}\×{10}^3)\left(\mathrm{dBm}\right)$

Substitution v _i ²Value is also established R=50 Ω.Draw the 1dB compression point:

P _i＝-22.1(dBm)

So

P ₀₁＝7.5(dBm)

2) P _TMDS(minimum detectable signal or sensitivity)

P _IMDS(dBm)＝-174+NF(dB)+10lgB

Supposing the system overall thermal noise, the Shot noise is total up to 4dB, NF=0dB, then

P _IMDS(dBm)＝-116.98(dBm)

That is to say that under limiting case the sensitivity that system can reach is-116.98dB.

Then have the system dynamics scope to be:

DR＝P ₀₁-P _IMDS＝123.48(dBm)

3) if input signal contains two frequencies, establish

v _i(t)＝v _i(cosw ₁t+cosw ₂t)

Then in Shu Chu the composition, contain fundamental frequency w ₁, w ₂, and triple-frequency harmonics 3w ₁, 3w ₂, third-order intermodulation product 2w ₁± w ₂, 2w ₂± w ₁Aliquot is formed.Generally speaking, has only 2w ₁-w ₂, 2w ₂-w ₁Drop in the band.This is the nonlinearity product that needs most consideration.

Therefore, just there is IP3 to be defined as 2w ₁-w ₂, perhaps 2w ₂-w ₁Power output P (2w ₁-w ₂) and frequency w ₁Linear power output P ₀(w ₁) the outer intersection point that moves back.

$v_o\left(t\right)=(k_1{v}_i+\frac{9}{4}{k}_3{v}_i^3+\frac{25}{4}{k}_5{v}_i^5+\frac{1225}{64}{k}_7{v}_i^7)\cos w_{1}t$

$+(\frac{3}{4}{k}_3{v}_i^3+\frac{25}{8}{k}_5{v}_i^5+\frac{735}{64}{k}_7{v}_i^7)\cos (2w_1-w_2)t+...$

$P\left(w_1\right)=10\lg [\frac{1}{2}\×\frac{{(k_1{v}_i+\frac{9}{4}{k}_3{v}_i^3+\frac{25}{4}{k}_5{v}_i^5+\frac{1225}{64}{k}_7{v}_i^7)}^2}{R}\×{10}^3]\left(\mathrm{dBm}\right)$

$P(2w_1-w_2)=10\lg [\frac{1}{2}\×\frac{{(\frac{3}{4}{k}_3{v}_i^3+\frac{25}{8}{k}_5{v}_i^5+\frac{735}{64}{k}_7{v}_i^7)}^2)}{R}\×{10}^3]\left(\mathrm{dBm}\right)$

$P_o=10\lg (\frac{1}{2}\×\frac{k_1^2{v}_i^2}{R}\×{10}^3)\left(\mathrm{dBm}\right)$

At IP3 point, P (2w ₁-w ₂)=P ₀, then have, $v_i^2=9.0600\×{10}^{-4}$

$\mathrm{IP}3=10\lg (\frac{1}{2}\×\frac{k_1^2{v}_i^2}{R}\×{10}^3)\left(\mathrm{dBm}\right)$

If R=50 is Ω,

IP3＝10.20(dBm)

IIP3＝IP3-G ₀＝10.20-30.63＝-20.43(dBm)

4) no spurious response dynamic range (SFDR) is:

Add at system input under the situation of constant amplitude two-tone signal, the receiver input signal is from surpassing noise gate 3dB to the power dynamic range that does not produce the third order intermodulation spurious response point place.

$\mathrm{SFDR}=P_u-P_{\mathrm{MDS}}=\frac{2}{3}(\mathrm{IIP}3-\mathrm{NF}-10\mathrm{lgB}+171)$

$=\frac{2}{3}(-20.43-4-53+171)=62.38\left(\mathrm{dBm}\right)$

Generally can adopt following measure to reduce disturbs and distortion:

Input adds frequency-selective network, and high frequency amplifies, but the gain that high frequency amplifies can not be too high;

Select square law device for use as far as possible;

The choose reasonable intermediate frequency;

Select suitable transistor working point electric current.

The NF of each device selection scheme (Noise Figure) Distribution Calculation:

Because what the present invention was designed is double-card mobile phone, its inner integrated two cover gsm systems so signal each other disturbs, are the main reasons that reduces system sensitivity.

We know by experiment, and when not adding antenna measurement, the 3GPP index is satisfied in sensitivity, but after adding antenna measurement, sensitivity reduces significantly, and whole system sensitivity by experiment, is-95dB as can be known, this index is underproof, can not satisfy Carrier Requirements.

Owing to be after adding antenna measurement, the sensitivity index rollback, so our analysis, at be exactly that the index that causes of the phase mutual interference between the antenna worsens.

After adding antenna, because what adopt is the double antenna framework, and taked dual standby mode, so, when an antenna emission, when an antenna receives, because two isolation between antennaes are not enough, just may make the useful signal that is received, drop on adjacent antenna and go in transmitting, useful signal is flooded by noise.

This problem is seen theoretically, is appreciated that into the third order intermodulation problem of two close frequencies, i.e. 2w ₁-w ₂Perhaps 2w ₂-w ₁, this influence, the consequence that is caused is the rollback of system sensitivity, has the experience formula to draw:

P ₁=101gN, wherein N=2

Be P ₁=6dB

This sensitivity rollback is difficult to handle from system's one-level.The minimum useful signal level that the limit can be surveyed is-115dBm.

Because the sensitivity target that need to realize is ,-108dBm, sensitivity that then can rollback is-7dB.If the sensitivity target that realizes is ,-102dBm, sensitivity that then can rollback is-13dB.The realization of this index need be analyzed the each several part module index of system.

Based on prior art, for example based on MEMS, the change over switch speed that the CMOS technology is designed has reached suitable level.Therefore, realize the switching of double SIM card, the technical difficulty that there is no from technological angle.Theoretically, by Synchronization Control to GSM standard time slot, utilize the switching of speed-sensitive switch, can realize the shared cover baseband processing module of double SIM card, words are not lost in standby, and can suppress the sensitivity rollback effectively, reach the desired gsm system index of 3GPP, and reduce the cost of double-card mobile phone.

The present invention utilizes the high speed diverter switch to carry out the switching of SIM card just, makes two cover systems be operated in different time slots, forms " taking turns " standby on the microcosmic.When the first radio-frequency front-end received signal, second radio-frequency front-end is in the radio listening silence state; When the second radio-frequency front-end received signal, first radio-frequency front-end is in the radio listening silence state.As shown in Figure 2, the time location of expressing two SIM card work of signal, when a SIM can insert, the first mobile phone system works; When the 2nd SIM can insert, the second mobile phone system works.

Embodiment

As shown in Figure 3, the double-card mobile phone that this is routine comprises first radio-frequency front-end, second radio-frequency front-end, baseband processor, diverter switch, the first SIM card interface, the second SIM card interface, and other functional units and power-supply system.In the first SIM card interface and the second SIM card interface, insert two SIM card with the corresponding GSM network of baseband processor standard.When diverter switch was connected first SIM card with baseband processor, first radio-frequency front-end makes up with it finished the first mobile phone systemic-function.When diverter switch was connected second SIM card with baseband processor, second radio-frequency front-end makes up with it finished the second mobile phone systemic-function.

After this routine double-card mobile phone start, by diverter switch, a shared cover GSM baseband processor is discerned two row that stick into, and this routine mobile phone has two kinds of mode of operations:

Double-card dual-standby pattern two cover radio systems are worked simultaneously, by quick SIM card change over switch, realize the double-card dual-standby function.When first cell phone system in running order (talking state), second cell phone system is in holding state, utilizes the first mobile phone system communication time slot to send response message to the base station, and the call accepted request signal.When second cell phone system receives call request signal, discern by baseband processor, number priority order according to user's definition in mobile phone communication is thin, notify the user in real time, whether be important phone, if as plain old telephone, and strange phone, then carry out record automatically, decide by the user and how to handle.The access situation of two SIM cards is seen Fig. 2.

The single deck tape-recorder standby mode is when the decline of power-supply system power supply capacity, perhaps the user has specific demand, in the time of need closing wherein a cover system, carrying out mode of operation by the cell phone keyboard button switches, by selection to operator, close wherein that a cover system enters the single deck tape-recorder standby mode, play energy-conservationly, economize the effect that takes.

This routine diverter switch is made of the SA630 single-pole double throw speed-sensitive switch of three Philips companies, and the annexation of they and baseband processor and SIM card as shown in Figure 4.The control end (ENABLE) of three SA630 single-pole double throw speed-sensitive switches is connected with baseband processor, and baseband processor is according to the communications time slot, and the mutual interference of two cover cell phone systems is avoided in the switching of control SIM card.

Claims (4)

1. double-card mobile phone comprises first radio-frequency front-end, second radio-frequency front-end, baseband processor, the first SIM card interface and the second SIM card interface; The first mobile phone systemic-function is finished in described first radio-frequency front-end and the described first SIM card interface and the combination of described baseband processor, and the second mobile phone systemic-function is finished in described second radio-frequency front-end and the described second SIM card interface and the combination of described baseband processor; It is characterized in that, also comprise diverter switch; The described first SIM card interface is connected with described baseband processor by described diverter switch with the described second SIM card interface, and described diverter switch is used to switch being connected of the described first SIM card interface and the described second SIM card interface and described baseband processor.

2. double-card mobile phone according to claim 1 is characterized in that, described baseband processor is controlled described diverter switch according to the communications time slot and switched being connected of the described first SIM card interface and the described second SIM card interface and described baseband processor.

3. double-card mobile phone according to claim 1 and 2 is characterized in that, described first radio-frequency front-end and described second radio-frequency front-end work in the communication network of same pattern.

4. double-card mobile phone according to claim 3 is characterized in that, described communication network is the gsm communication network.

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